Winter 2007 Vol 10.
ISSN 1366–4697
The Journal of MAXILLOFACIAL PROSTHETICS & TECHNOLOGY
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
PUBLICATION: THE JOURNAL OF MAXILLOFACIAL PROSTHETICS & TECHNOLOGY is published by: Type Script, 7 Carmelite Way, Hartley, Kent DA3 8BP, UK. Tel: 01474 707896 E-mail: design@typescript.plus.com ADVERTISING SALES: Contact Dr M. Anwar Bamber, Dept. of Oral and Maxillofacial Surgery, UCL Eastman Dental Institute, University of London, London WCIX 8LD, UK. E-mail: a.bamber@eastman.ucl.ac.uk Tel: 0044 (0)20 7915 1226 COPYRIGHT: ISSN 1366-4697 © The Institute of Maxillofacial Prosthetists & Technologists, 2006. No part of this publication may be reproduced without the express permission of the Editor. Permission is not required to copy abstracts on condition that a full reference to the source is shown. SUBSCRIPTIONS: Members are reminded that if their subscriptions to The Institute of Maxillofacial Prosthetists & Technologists are out of date, the Journal cannot be supplied. Subscriptions for the Journal cost £40 per issue. Cheques should be made payable to The Institute of Maxillofacial Prosthetists & Technologists and sent to: 7 Carmelite Way, Hartley, Kent DA3 8BP, UK. MEMBERSHIP & CHANGE OF ADDRESS: All matters relating to the membership of The Institute of Maxillofacial Prosthetists & Technologists should be sent to: The Honorary Registrar Mr M. Pilley, Prosthesis Clinic, Maxillofacial Unit, Leicester Royal Infirmary, Leicester LE1 5WW. Tel: 01162 585255
All queries regarding subscription should be sent to: Mr R. Eggleton Honorary Treasurer Department of Medical Physics & Oncology, St. Luke’s Cancer Centre, Royal Surrey County Hospital, Edgerton Road, Guildford, Surrey GU2 7XX. Tel: 01483 406640
Internet website: http://www.impt.org Registered as a Charity. Registered in England under Charity Number 101 3059 A Company Limited by Guarantee. Registered in England under Company Registration No. 2334615 Registered Office: 818 High Street, Kingswinford, West Midlands DY6 8AA, UK.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
iii
The Journal of Maxillofacial Prosthetics & Technology
TS IS
TE ITU ST IN
ISTS & TECHN OL HET ST OG RO
OF MAXILLO FAC IA L
P
TH E
EDITOR: DR M. ANWAR BAMBER Department of Oral and Maxillofacial Surgery, UCL Eastman Dental Institute, University College London, University of London, London WCIX 8LD, UK. EDITORIAL BOARD:
ALAN BOCCA Maxillofacial Unit, Morriston Hospital, Swansea SA6 6HL RICHARD BIBB Medical Applications, PDR, UWIC, Western Avenue, Cardiff CF5 2YB STEVE BAILEY Maxillofacial Unit, Pilgrim Hospital, Sibsey Road, Boston, Lincolnshire PE21 9QS JASON WATSON Maxillofacial Unit, Queens Medical Centre/University Hospital, West Block, B Floor, Derby Road, Nottingham NG72 UH
EDITORIAL ADVISORY BOARD: K. F. MOOS OBE – Scotland I. COLLINS – England M. CUTLER – England N. SAPP – England K. E. THOMAS – England G. GRANSTRÖM – Sweden A. LINNEY – England G. H. WILKES – Canada C. MARYAN – England C. NACHER – Spain R. LEESON – England V. SALIH – England C. BETZ – Germany
J. S. BROWN – England M. P. ROTHERA – England P. EVANS – Wales A. TJELLSTRÖM – Sweden F. P. JOHNSON – England A. VACHIRAMON – Thailand C. HAYLOCK MBE – England A. E. MARKUS – England J. WOLFAARDT – Canada S. J. WORROLLO – England P. BARRETT – Wales D. BREWER – England C.E. CLUFF – England
THE INSTITUTE OF MAXILLOFACIAL PROSTHETISTS & TECHNOLOGISTS COUNCIL 2007 PRESIDENT S. FISHER FDSRCS, FRCS PRESIDENT ELECT P. RAMSAY-BAGGS MB BCH BAO BDS FDS RCS(ENG) FFD RCSI FRCS(ED) S. PARKINSON CHAIRMAN SECRETARY M. TOWNEND HON. TREASURER R. EGGLETON HON. REGISTRAR M. PILLEY COUNCIL MEMBERS D. ALLEN K. PAGE MBE M. BAMBER M. PILLEY B. EDWARDS S. QUINN R. EGGLETON M. TOWNEND L. GILL F. WALKER R. JENNER J. WATSON
iv
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
EDITORIAL The Partnership: Patient, Public and the IMPT Why should a membership organisation involve itself with the non-fee paying public? Many years ago, the Institute successfully negotiated charitable status, which recognises its primary role in fostering the education and training of Maxillofacial Prosthetists, as such it sets standards similar to many other independent organisations. Throughout its relatively short history, as many of you will know, the IMPT has been keen to have an open dialogue not only with its membership but also with those outside the medical and dental professions. It is important for both patients and clinical practice that the public understand the possibilities and the limitations of modern healthcare. Since the late-seventies, we have specifically welcomed those from within and outside the medical profession to our forums to generate a mutually constructive dialogue. Representatives of the IMPT have attended a series of meetings organised by various charities – targeted at patients with a specific illness or condition. We have also contributed in meetings to introduce school children to career options in allied healthcare professions. In collaboration with NHS Careers we published a useful series of fact sheets for prospective trainees, patients and for other members of the general public. We have hosted a number of events to which those outside healthcare have been invited, either as part of the audience or as guest speakers. Christine Piff from Let’s Face It addressed our conference audience to share her experiences as a patient with facial defect; this in turn inspired a number of other initiatives. Allowing the public as patients benefit from the superb educational opportunities we provide nationally and internationally to members and non-members across all disciplines. But to comply with the new Charities Act, we now need to put this engagement with the public on a more formal, statutory footing. Although the Act itself does not clearly define ‘public benefit’, guidance from the Charity Commission identifies two key principles charities must satisfy: there must be an identifiable benefit in a charity’s activities, and the benefit must be to the public or a section of the public. Factors such as activity hours, geographical location or not being a member of the charity in question should not restrict someone from benefiting. The guidance also clearly specifies that people living in poverty must not be excluded from the opportunity to benefit. The commission will carry out spot checks to gauge a charities’ compliance from the end of the financial year 2008/09. The IMPT already aim for its provision for public benefit, but it now becomes a statutory requirement. Perhaps the IMPT like some other organisations may need to set up a Public Engagement Group (PEG) which meets a few times a year on an ongoing basis. However, for this to be effective, this group would need to be made up of patients, members of IMPT, the Council and outside organisations from non-medical backgrounds. The group would need to explore a wide range of initiatives to increase our interaction with the public. These could include a series of public debates on controversial topics such as the need for statutory registration, healthcare rationing, patients’ rights and patients’ responsibilities, and conventional versus implant supported prostheses. This group would also need to engage the media programme makers and broadcasters for public benefit.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
v
These future seminars and exhibitions could be attended by Members and non-members alike, and some of the exhibitions planned for the year ahead could also be open to the public with no admission charge. We need to look at making a number of free places available for prominent members of the public to attend certain meetings and conferences. This would be in addition to making some events available for viewing online via our website. We ought to be looking into the idea of expanding our website content to develop e-bulletins that members of the public can elect to receive. If you have any ideas about initiatives to further engage with the public or if you’d like to join and contribute please get in touch with an IMPT council member. The IMPT Council invites you to get engaged. To have a ‘Maxillofacial Prosthetic service which is identifiable but integrated in the healthcare system’ would be a laudable vision indeed. But is it feasible? Despite having been sidelined by some statutory authorities it must be right to adopt a positive view of the future. Surely the benefits for patients will become more visible sooner rather than later? The aims of the IMPT are comprehensive and fulfilling, although I might move the last – ‘putting the patient at the focus of our work’ – further up the list. Maybe the tide is turning in our favour in a funny sort of way, this presents an exciting challenge for the Council and members alike! Summer – such as it was – is over and the nights are fair drawing in as folk up in Scotland say. This would be a good time to turn your thoughts to the next journal for which the first call for papers has been issued.
M. Anwar Bamber Hon. Journal Editor
vi
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
CONTENTS
PAGES A WEIGHT COMPARISON OF SURGICAL PACKING MATERIALS USED FOR MAXILLECTOMY OBTURATION R. Jenner MEASURING ADEQUACY OF RETENTION OF MINI DENTAL IMPLANT IN LOWER FULL DENTURES WITH FLAT RIDGES: AN IN VITRO STUDY C. B. Koay, C. C. Chee, J. Y. Sia, R. A. Rahman, C. L. Koay, M. N. Jabar
1–4
5–8
DIGITAL TECHNOLOGIES IN EXTRA-ORAL, SOFT TISSUE FACIAL PROSTHETICS: CURRENT STATE OF THE ART D. Eggbeer, R. Bibb and P. Evans
9–16
FLEXIBLE JAW EXERCISER: AN ALTERNATIVE APPLIANCE FOR TRISMUS REHABILITATION C. Orbaneja Botija
17–22
EXTERNAL HOLLOW BUTTOCK PROSTHESIS P. Kaur and D. Coppins
23–26
DIGITAL PHOTOGRAPHY IN MAXILLOFACIAL PROSTHETICS N. Caulfield and C. Maryan
27–30
TITANIUM CRANIOPLASTY IMPLANT CONSTRUCTION USING A SECTIONAL MOULD B.C. EDWARDS
31–33
ABSTRACTS
34–39
INSTRUCTIONS TO AUTHORS
41–42
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
vii
Medical Applications Group
> Precise models of patient anatomy built directly from your CT or MRI data > Our stereolithography models are transparent and strong > Theatre models are available (Tested to USP 23 Class 6) > Selective colouring of designated tissues is available > Models for: cranioplasty plates, tumour reconstruction, siting osseointegrated implants, osteotomy planning and symmetrical reconstruction > PDR undertakes research and development projects in the application of design and manufacturing technologies in reconstruction and rehabilitation For further information, please contact Dr Dominic Eggbeer or Dr Richard Bibb: Tel: 029 2041 6703 Fax: 029 2041 6973 email: deggbeer-pdr@uwic.ac.uk or rbibb-pdr@uwic.ac.uk
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
A WEIGHT COMPARISON OF SURGICAL PACKING MATERIALS USED FOR MAXILLECTOMY OBTURATION R. Jenner Rachel Jenner MIMPT Maxillofacial & Orthodontic Laboratory Kent & Canterbury Hospital East Kent Hospitals NHS Trust Canterbury, Kent CT1 3NG
The aim of this study is to compare the weight of packing materials used for immediate surgical obturation. In addition to the weight of the obturator, an evaluation of material retention methods was assessed. Key: maxillectomy, obturator, Gutta-percha, addition silicone, silastic foam, Taguchi Orthogonal Array.
INTRODUCTION Throughout recent literature there have been many descriptions of the use and value of surgical obturators1–4. The functional importance of these devices cannot be stressed enough; they restore the patient’s masticatory function, improve their speech and lend support to surgical dressings whilst, at the same time, supporting the surrounding facial tissues. The support of those surrounding tissues is especially important as these will help to restore the patient’s self image at a delicate and stressful stage of treatment. Lapointe, et al (1996)5, compared the merits of immediate and delayed obturator prosthesis placement in maxillectomy patients. His retrospective study concluded that immediate obturation benefited the patient and their progress to recovery. In terms of material considerations, Gutta-Percha (GP) has remained the favourite for surgical packing in maxillectomy patients. This inelastic natural latex, produced from the sap of Pallaquium trees bio-inert properties make it suitable for surgical dental devices6. Steadman (1957)7 describes the use of an acrylic plate lined with gutta-percha to support a skin graft to the maxillary defect. Although a surgeon’s favourite, this choice of material has displayed disadvantages to the patient. Namely it has a taste and smell not always pleasant for the patient during the healing process, and once set, it is rigid and heavy in mass. With the lack of raw materials, resulting in a global shortage of GP, it is appropriate to look at the alternatives available.
In 1984 Radcliffe et al8, presented the idea for a lightweight surgical obturator with use of silastic foam as an alternative to GP. Buckle (1998)9–10, also highlighted the use of silastic foams for immediate obturation. He explained the advantages of combining Nusil R 2370 and Med 6382 (Polymer Systems Technology Limited, Unit 2 Network 4, Cressex Business Park, Lincoln Road, High Wycombe) over the more traditional material GP. Addition silicones are widely used in the oral cavity as a high precision impression material, they also act as good surgical dressing material in obturation cases. It can provide stable, clean support to the surrounding healing tissues with accurate detail of the cavity. This detail can subsequently assist in the next process of temporary obturation, providing an excellent replica of the defect.
METHOD AND MATERIALS The original method was to compare the weight difference of materials used in packing surgical obturator defects, based on different sized defect cavities assessed as small, medium and large. It was felt that this required further definition; therefore several maxillectomy classifications were considered11–12, 17–20. The final method used Class 2 Low alveolar maxillectomy, not including the orbital floor or contents. This is described by Brown et al, as a modified classification for the maxillectomy defect12–14. Brown’s approach to palatomaxillary reconstruction has become a useful functional classification for maxillectomy defects. His system is based on both vertical and horizontal dimensions of a defect. All the cases chosen were edentulous.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
1
When considering the design of the dressing plate, another factor that can affect the overall weight could be the retention aid used for locating or attaching the dressing material to the plate. Traditional techniques include a wire ‘goal post’ or acrylic stud shape added to the fitting surface. If looking for areas to reduce the overall weight, then perforations could provide the solution. Within industry, Taguchi’s Orthogonal Arrays15 make it possible to experiment with the component parts of a product during the design stages of that product’s design and manufacture. Factors such as variation in the chemical ratio, or the ingredients used, or even the ways in which the product is formed all contribute to the final product. Orthogonal Arrays are a set of tables laid out by Taguchi to chart the design experiments.
For each of the classification sets, one of three types of obturator retention method were assigned; perforations (limited to 3), an acrylic stud or a wire goal post. Once these were applied to the base plates, the final factor was allocated. The three obturator packing materials were; Black Gutta Percha sheets, Epiform-flex an addition silicone (Dreve Dentamid GmbH, Max-Planck-Str.31, 59423 Unna, Germany) and Nusil R-2370 silastic foam (Polymer Systems Technology Limited, Unit 2 Network 4, Cressex Business Park, Lincoln Road, High Wycombe). This is illustrated in Table 1 (Fig. 1). Each cavity was filled with the designated material and attached to the appropriate base plate. All handling instructions supplied with the materials were followed carefully. All nine cases were then weighed individually; using an electronic balance, the total weight of each appliance was recorded.
The type of Orthogonal Array will differ depending on the number of variables to be considered, and how many levels those variables take. This method of analysis is used to provide us with the best parameters for the optimum design. The advantage of an Orthogonal Array is that it can be applied to an experimental design involving a large number of design factors. In the case of this experiment, to test each combination of size of defect, material used and method of retention employed, twenty-seven separate samples would need to be constructed. With Taguchi’s Orthogonal Array L9, only nine samples are needed (Table 1). Replica Kaffir-D models were produced in triplicate for each classification. For the purpose of this experiment, it was not necessary to incorporate circum-zygomatic retention components or aesthetic teeth onto the base plate. Therefore clear edentulous acrylic base plates were constructed for the nine experimental models, Meadway Superclear Heatcure (MR Dental, 4 Manor Way, Old Woking, Surrey). Each classification set of base plates were trimmed and polished to ensure that they weighed the same at this stage of the experiment.
Fig. 1: Defect models and the application of the different materials.
Table 1: L9 Orthogonal Array Experiment Table; showing factors applied and levels measured (L1, 2, 3) Number of Levels Experiment No. (Parameters)
2
Classification
Retention
Material
1
L1 – Class 2b
L1 – Perforations
L1 – GP
2
L1 – Class 2b
L2 – Acrylic Stud
L2 – Silicone
3
L1 – Class 2b
L3 – Goal Post
L3 – Foam
4
L2 – Class 2a
L1 – Perforations
L2 – Silicone
5
L2 – Class 2a
L2 – Acrylic Stud
L3 – Foam
6
L2 – Class 2a
L3 – Goal Post
L1 – GP
7
L3 – Class 2c
L1 – Perforations
L3 – Foam
8
L3 – Class 2c
L2 – Acrylic Stud
L1 – GP
9
L3 – Class 2c
L3 – Goal Post
L2 – Silicone
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
RESULTS
obturator can healthily stay in the cavity; this also highlights the patients issue around smell and taste.
The results show that silicone is the lightest packing material, therefore more effective on weight reduction. The larger the defect size, the greater the weight reduction when using foam. When assessing the retention components, perforations eliminate additional weight to the plate; the results help show the impact back-up retention aids have on the overall weight on the appliance (Table 2). The results for each factor; classification Class 2a, b and c, retention method and obturator material, were taken and added together and divided by three to calculate their mean average (Table 3).
DISCUSSION As expected, Silastic foam is more effective on weight reduction. From the authors’ experiences throughout this experiment, the foam was not always easy to handle. The mixing technique and time can be limiting, therefore it would be advisable to practice with its application before working in a theatre environment or pressurised situation. One known surgical procedure when using this material involves the Webber Ferguson technique, which allows open access to the cavity. The manufacturers notes state the quantity of catalyst can affect the expansion, it is therefore important to accurately measure both component parts. Additionally the temperature of the working environment is an important factor to consider. The hospital theatre environment is likely to be warmer than the laboratory and this could have an effect of reducing the setting and expansion time of the foam. Care has to be taken when the foam is in final stages of expansion, if touched it is liable to implode resulting in some failure of set. The R-2370 foam can be strengthened and lifetime increased by blending 75% R-2370 and 25% MED 63829. There is some concern around the length of time a foam
Perforations in the base plate, as a method of retention, also provide a reduction of the overall weight. Perforations are easier to incorporate into the base plate during construction and negate the need for auxiliary retention components, also eliminating additional weight. This is not a satisfactory retention method for all the materials, if it is necessary to keep the plate and obturator as one-piece. With the exception of silastic foam there are limitations on the use of dressing materials if using a one-stage packing process. The size, and specifically, the undercut areas of the defect site can cause complications at removal of the surgical dressing plate. Both Silicone and Gutta Percha although giving a good supportive structure, can be difficult to remove once they become locked into an undercut area, if an ‘sectional impression’ technique has not been used! Gutta Percha does have the properties that enable modifications or additions, enabling the operator to remould or build up areas. Once set, silicone does not allow the operator to create a successful bond and enable them to add further material. Although having the ability to build-up in sections, using silicone putty can be beneficial. The operator would be able to engage useful undercuts and ensure that each section is removable. In conclusion, Brown’s multidisciplinary (surgical and prosthodontic) classification describes the type and extents of surgery, but the overall volume of the defect is still varied within each classification boundary, as this depends on each case. It will ultimately be the operators’ decision as to the most suitable packing material and method used, dependant on the volume of defect.
Table 2: Total weight of immediate obturators (grams) Classification
Retention
Material
Total Weight (grams)
1
Class 2b
Perforations
Gutta-Percha
26.55
2
Class 2b
Acrylic Stud
Silicone
25.03
3
Class 2b
Goal Post
Foam
15.54
4
Class 2a
Perforations
Silicone
41.23
5
Class 2a
Acrylic Stud
Foam
19.29
6
Class 2a
Goal Post
Gutta-Percha
49.93
7
Class 2c
Perforations
Foam
32.41
8
Class 2c
Acrylic Stud
Gutta-Percha
77.50
9
Class 2c
Goal Post
Silicone
98.30
Experiment No.
Table 3: Surgical obturation dressing methods – Mean Average weight calculated for each level and factor measured (grams) Size (grams)
Retention (grams)
Material (grams)
Level 1
22.37
33.39
51.32
Level 2
36.81
40.60
54.85
Level 3
69.40
54.59
22.41
Biggest difference
47.03
21.2
32.44
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
3
Acknowledgements I would like to thank Mr J. McKenzie, Consultant Maxillofacial Surgeon, for his assistance in the compilation of this paper. I also express my thanks to my colleagues at Kent & Canterbury Hospital for all their support; Mr S.J. Abbott and Mr J.A. Couchman. I would also like to thank Polymer Systems Technology Limited for their product guidance and for providing samples to carry out this experiment.
References 1. Huryn J.M., Piro J.D. The maxillary immediate surgical obturator prosthesis. J Prosthet Dent. 1989; Mar: Vol 61, No 3; 343–347. 2. Black W.B. Surgical obturation using a gated prosthesis. J Prosthet Dent. 1992: 68: 339–342. 3. Keyf F. Obturator prostheses for hemi-maxillectomy patients. J Oral Rehabil. 2001; Vol: 28, Issue 9; 821. 4. Freidline C.W. Immediate prosthetic obturation of the partially resected maxilla in edentulous patients. J Prosthet Dent. 1980; Vol: 44, No 1; 72–73. 5. Lapointe H.J., Lampe H.B., Taylor S.M. Comparison of maxillectomy patients with immediate versus delayed obturator prosthesis placement. J Otolaryngol. 1996; Oct: 25 (5); 308–12. 6. Anderson J.N. Applied Dental Materials, Blackwell Scientific Publications. 1956. 7. Steadman B. St J. Construction of prosthesis after resection of the maxilla. Int Dent J. 1957; 7; 560. 8. Radcliffe G.J., Mady S., Burr R., Cheeseman A.D., Wilson D. A new immediate temporary lightweight obturator for maxillectomy cavities. Br J Oral Maxillofac Surg. 1984; 22: 50–53. 9. Buckle J.P. Adaption and application of silicone foams. J Maxillofac Prosthet Tech. 1998; Vol: 2 Issue: 1; 27–29.
4
10. Polymer Systems Technology Limited. Product Data Sheet for R2370 and instruction booklet. 11. Okay D.J., Genden E., Buchbinder D., Urken M. Prosthetic guidelines for surgical reconstruction of the maxilla: A Classification system of defects. J Prosthet Denti. 2001 Vol: 86, No 4; 352–363. 12. Brown J.S., Rogers S.N., McNally D.N., Boyle M. A modified classification for the maxillectomy defect. Head & Neck. 2000 Jan: 22 (1); 17–26. 13. Brown J.S. Deep circumflex iliac artery free flap with internal oblique muscle as a new method of immediate reconstruction of maxillectomy defect. Head & Neck. 1996 Sept/Oct: 18; 412–421. 14. Rogers S.N., Lowe D., Brown J.S., Vaughan E.D. Healthrelated quality of life after maxillectomy: A comparison between prosthetic obturation and free flap. J Oral Maxillofac Surg. 2003: 61; 174–181. 15. Peace G. Taguchi Methods – A hands on approach. Addison-Welsey Publishing Group Inc. 1993: 122–127. 16. Cunningham R. A laboratory technique for the production of immediate surgical appliances and ‘one-stage’ obturators for the hemi-maxillectomy patient. Br J Oral Maxillofac Surg. 1990; 28: 59–61. 17. Koyama S., Sasaki K., Inai T., Watanbe M. Effects of defect configuration, size and remaining teeth on masticatory function in post maxillectomy patients. J Oral Rehabil. 2005; Vol: 32, Issue 9; 635. 18. Cordeiro P.G., Santamaria E. A Classification System and Algorithm for Reconstruction of Maxillectomy and Midfacial Defects. Plastic and Reconstr Surg. 2000: Vol: 105, No. 7; 2331–2346. 19. Aramany M.A. Basic principles of obturator design for partially edentulous patients. Part I: classification. J Prosthet Dent. 1978; 40: 554–7. 20. Aramany M.A. Basic principles of obturator design for partially edentulous patients. Part II: design principles. J Prosthet Dent. 1978; 40: 656–62.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
MEASURING ADEQUACY OF RETENTION OF MINI DENTAL IMPLANT IN LOWER FULL DENTURES WITH FLAT RIDGES: AN IN VITRO STUDY C. B. Koay, C. C. Chee, J. Y. Sia, R. A. Rahman, C. L. Koay, M. N. Jabar Dr Mohd Nazimi Abd Jabar (to address all correspondence and mailing) Dept of Oral and Maxillofacial Surgery, Universiti Kebangsaan Malaysia Medical Centre [UKMMC] Jalan Yaacob Latif, Cheras 56000 Kuala Lumpur MALAYSIA Dr Koay Choon Bok Dental Officer Dept of Oral and Maxillofacial Surgery, Universiti Kebangsaan Malaysia Medical Centre [UKMMC] Jalan Yaacob Latif, Cheras 56000 Kuala Lumpur MALAYSIA
Dr Chee Chu Cheet and Dr Sia Jye Yen Dental Officer Ministry of Health MALAYSIA Dr Roslan Abdul Rahman (Associate Professor) Dept of Oral and Maxillofacial Surgery, Universiti Kebangsaan Malaysia Medical Centre [UKMMC] Jalan Yaacob Latif, Cheras 56000 Kuala Lumpur MALAYSIA Dr Koay Chuan Lek Private Dental Practitioner MALAYSIA
Objectives: The aim of this study was to evaluate and report the retention force of the IMTEC Sendax MDI System. Method and materials: The experimental model with four MDI Classic implants (1.8mm x 18mm) was used and the respective overdenture was prepared with the O-ring housing embedded. Tensile strength tests (Micro 500) were performed to measure the maximum dislodging force (peak load) of the overdenture with 4 O-rings, 2 O-rings and 1 O-ring attached. The test was repeated ten times for each group at a speed of 50mm/min. Data were analysed to calculate the mean, standard deviation and mean confidence interval at 95%. Results: Results showed mean force of 2.790 ± 0.095 N for 1 O-ring attached, 5.527 ± 0.178 N for 2 O-rings and 8.946 ± 0.847 N for 4 O-rings. The peak load of 2 O-rings appeared to be twice that of 1 O-ring. However, the peak load of 4 O-rings was less than four times the peak load of 1 O-ring. Discussion: Lehmann & Arnim recommends 5 to 7 N as the minimum force required for overdenture stabilisation. The peak load (8.946 N) of the overdenture with four O-rings has exceeded this recommendation. Conclusion: Based on the study, the O-ball prosthetic head of the IMTEC Sendax MDI provide adequate in vitro retention for lower full dentures when used in flat, severely resorbed mandible. It can be considered as adjunct or as long-term measure to address the lower overdenture retentive problem in cases where inadequate bone volume in supporting standard-diameter implant is present. However, further research is needed to further verify their in vivo use and success. Keywords: mini-implant, retention, retention measurement, Sendax, severely resorbed mandible.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
5
INTRODUCTION The IMTEC Sendax Mini Dental Implant (MDI) System was approved for long-term use by the United States Food and Drug Administration (FDA) in 2003. It is the first and only reduced-diameter implant system to receive approval for long-term use. The device permits immediate splinting ability and long-term fixation of new and existing crown and bridge installations, for full partial edentulism, and employs minimally invasive surgical intervention1. There are four MDI designs available: Classic, Classic MAX, Collared, and Collared MAX. The standard design has a diameter of 1.8mm while the MAX design has a 2.4mm design. They each have four lengths: 10, 13, 15 and 18mm and two attachment systems: O-ball and square prosthetic head2.
be feasible in an in vivo situation. A total of 30 tests were conducted and the results of each test recorded automatically by the computer interface. The components removal and insertion were only performed along the long axis of the implants avoiding any unnecessary flexural or horizontal load.
Statistical analysis The results of peak load of all groups were summarised and tabulated following the tests conducted. Statistic and analysis was carried using Statistical Package for the Social Sciences (SPSS) version 11.0. Mean and standard deviation were calculated to demonstrate the distribution of peak load tests performed. Confidence interval was used to test the reliability of an estimate of the dislodging force.
Following success in the temporary prosthetic stabilisation during the healing period of standard diameter implant3,4, their use has been extended in orthodontic anchorage5, in temporary fixation of transplanted teeth6, periodontal therapy7 and more recently in the long-term fixed and removable prosthetics8–10. As there have been many studies and publications previously conducted to the various attachment systems of the standarddiameter implants in lower full dentures, we sought to evaluate the adequacy of MDI retention force when used to retain overdentures in this in vitro analysis. According to Lehmann & Arnim, forces from 5 to 7 N should be sufficient to stabilise overdentures during function11.
Fig. 1: Four O-ring metal housing embedded into the overdenture.
MATERIALS AND METHODS Specimen preparation The experimental model was prepared with four 18mm MDI Classic with O-ball attachment system mounted according to the patented insertion protocol2,12. The implants were placed in the inter-canine region. An overdenture with the O-ring metal housing embedded corresponding to the model with implants was manufactured (Fig. 1). No undercuts were present. The model was fixed to the universal testing machine using a clamp while a device to attach the overdenture was fabricated (Fig. 2).
Retention measurements The peak load (maximum dislodging force) was measured in N using a universal testing machine (Micro 500) with a computer interface. Traction was applied at 50mm/min, which was reported to approximate the speed of the movement of the denture away from the ridge during mastication13. The peak load was measured 10 times with 4 O-rings attached. Following completion, 2 rings were removed and the peak load was measured again 10 times. Finally, another ring was removed and the maximum dislodging force was again measured 10 times. This additional test was carried out to ascertain whether the dislodging force has a proportionate increment with the number of mini implant used, although this could not
6
Fig. 2: The model attached to the testing machine.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
RESULTS
Maximum Dislodging Force (N)
The peak load tests results with statistical summaries are presented in Table 1 and Fig. 3. Dislodging force ranged from a minimum of 7.553 to a maximum of 10.191 N for overdentures with 4 O-rings attached; 5.132 to 5.809 N for 2 O-rings; and 2.577 to 2.912 N for 1 O-ring.
8.000
The IMTEC Sendax MDI Classic has a diameter of 1.8mm. This allows it to be placed when inadequate bone is present (e.g. edentulous arches with flat ridges) without the need for the added costs and trauma of bone grafting and other invasive procedures usually associated with conventional standard-diameter implants15. The minimally invasive procedures also means that MDIs may be placed in patients who are medically compromised when standard-diameter implants may not be a viable option. The MDI surgical protocol is a much simplified procedure, most of the time not requiring the raising of a mucoperiosteal flap2. The armamentarium for MDI placement consists of only five components (Fig. 4). This simple procedure makes it easier for implant placement and a shorter time required. It is also possible for immediate loading of the MDIs and hence, immediate improvement in denture retention and function.
6.000 4.000 2.000
1 Ring
2 Rings
4 Rings
O-Rings Fig. 3: Mean values and 95% confidence interval (error bars) of the dislodging force of the 3 groups tested.
The ball attachment system, which is utilised by the IMTEC Sendax MDI, is favoured by some authors to retain mandibular overdentures due to the favourable ratio between the supporting bone structures and the forces acting during function and parafunction16.
DISCUSSION Retention can be considered as the force that resists withdrawal along the path of insertion13. Since the path of insertion of a mini-implant retained overdenture lies along the long axis of the implants, this investigation studied the peak load measurements along the long axis of the implants. Resistance to anterior-posterior dislodging force has also been referred to as ‘stability’14, however was not studied in this investigation. The results showed that with only one ring in place, the maximum dislodging force is 2.79 N. With two rings in place, the result showed a peak load of 5.527 N, which is twice the force of one ring. This result lies within the acceptable range for denture stabilisation recommended by Lehmann & Arnim11. Nevertheless, it is not recommended for only two implants to be placed for this purpose. The peak load of the overdenture with four rings in place (8.946 N) is lower than the expected value of four times the maximum dislodging force of one ring. However, this may be beneficial for patients who have difficulty inserting and removing the overdenture such as patients with poor manual dexterity. The maximum dislodging force also exceeded the recommendation by Lehmann & Arnim11 of 5 to 7 N required for denture stabilisation during function.
Fig. 4: Armamentarium for placement of IMTEC Sendax MDI
STUDY LIMITATION The testing was done in specific and limited mechanical conditions. As such, this in vitro testing does not entirely replicate the function of dentures in the complex environment of the oral cavity. Additional experimentation should involve multidirectional force application (anterior-posterior and oblique), various fluids and thermal environments, fatigue effects and clinical trials to evaluate the attachment system that was investigated here.
Table 1: Results of peak load tests of all groups Group
Dislodging Force (N)
Maximum (N)
Minimum (N)
4 O-rings
8.946 ± 0.847
10.191
7.553
2 O-rings
5.527 ± 0.178
5.809
5.132
1 O-ring
2.790 ± 0.095
2.912
2.577
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
7
CONCLUSIONS The maximum dislodging force was determined along the long axis of the implants for 4 O-rings, 2 O-rings and 1 O-ring. Based on the results of this study, it could be concluded that: 1. The O-ball prosthetic head of the IMTEC Sendax MDI provide adequate in vitro retention for lower full dentures when used in flat, severely resorbed mandible. 2. The use of the MDI could be considered as adjunct or as long-term measure to address the lower overdenture retentive problem in cases where inadequate bone volume in supporting standard-diameter implant is present. 3. The use of the MDI could be an alternative option to patients who do not desire invasive implant surgical procedures or in patients who are medically or surgically compromised, or even in patients who are financially challenged. However, further research is needed to further verify the in vivo use and success of the IMTEC Sendax MDI in maintaining the retention of full dentures in flat mandibular ridges.
4. Petrungaro P.S., Windmiller N. Using transitional implants during the healing phase of implant reconstruction. Gen Dent. 2001; 49: 46–51. 5. Kanomi R. Mini-implant for orthodontic anchorage. J Clin Orthod. 1997; 31: 763–767. 6. Nagata M., Nagaoka S. Mini-implant is effective as a transitional fixation anchorage for transplantation of teeth. Jap J Cons Dent. 2002; 45: 69. 7. Nagata M., Nagaoka S. Preservation of the natural teeth and arch integrity by the use of transitional mini-implants. J Periodontol. 2000; 71: 1910. 8. Ahn M.R., An K.N., Cho J.H. et al. Immediate loading with mini dental implants in the fully edentulous mandible. Implant Dent. 2004; 13: 367–372. 9. Mazor Z., Steigmann M., Leshem R. et al. Mini-implants to reconstruct missing teeth in severe ridge deficiency and small interdental space: a 5-year case series. Implant Dent. 2004; 13: 336–341. 10. Bulard R.A., Vance J.B. Multi-clinic evaluation using mini-dental implants for long-term denture stabilisation: a preliminary biometric evaluation. Compend Contin Educ Dent. 2005; 26: 892–897.
DISCLOSURE
11. Lehmann K.M., Arnim F.V. Studies on the retention forces of snap-on attachments. Quintes Dent Technol. 1978; 7: 45–48.
None of the authors have any financial interests in the mini implants mentioned in this article.
12. Sendax V.I. Dental implantation. U.S. Patent 5749732 May 12, 1998.
References
13. Sarnat A.E. The efficiency of cobalt samarium (Co5Sm) magnets as retentive units for overdentures. J Dent. 1983; 11: 324–333.
1. Food and Drug Administration. IMTEC Sendax MDI and MDI Plus. U.S 510(k) Premarket Notification K031106. 2. IMTEC Corporation. IMTEC MDI Sendax: Long Term Denture Stabilisation. http://www.imtec.com/cgi-bin/janus.cgi?ID=MDI4.pdf 3. El Attar M.S., El Shazly D., Osman S. et al. Study of the effect of using mini-transitional implants as temporary abutments in implant overdenture cases. Implant Dent. 1999; 8: 152–158.
8
14. Petropoulos V.C., Smith W. Maximum dislodging forces of implant overdenture stud attachments. Int J Oral Maxillofac Implants. 2002; 17: 526–535. 15. Christensen G.J. The ‘mini’-implant has arrived. J Am Dent. Assoc Mar 2006; 137: 387–390. 16. Svetlize C.A, Bodereau E.F. Comparative study of retentive anchor systems for overdentures. Quintessence Int. 2004; 35: 443–448.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
DIGITAL TECHNOLOGIES IN EXTRA-ORAL, SOFT TISSUE, FACIAL PROSTHETICS: CURRENT STATE OF THE ART D. Eggbeer, R. Bibb and P. Evans Dominic Eggbeer AIMPT (corresponding author) and Richard Bibb PhD AIMPT The National Centre for Product Design and Development Research University of Wales Institute, Cardiff Western Avenue Cardiff CF5 2YB
Peter Evans MIMPT Maxillofacial Unit
Morriston Hospital Swansea SA6 6NL
An Action Research approach was taken utilising multiple case studies to evaluate the current capabilities of digital technologies in maxillofacial prosthetics. The research sought to establish quality, economic, technological and clinical implications. This article summarises the research and provides a discussion of the findings and implications for the field of Maxillofacial Prosthetics & Technology. Conclusions on the current capabilities and future developments are made. Keywords: 3D scanning, computer-aided design, digital, design, prosthesis, rapid prototyping.
INTRODUCTION The field of Maxillofacial Prosthetics & Technology is faced with increasing patient numbers within an increasingly costconstrained healthcare system leading to a desire to explore whether computer-aided, Digital Technology (DT) techniques can achieve cost or delivery time savings1. Digital Technologies such as Computer-Aided Design (CAD), 3D scanning and Rapid Prototyping (RP) have found limited application in extra-oral, maxillofacial prosthetics and there have been a number of research studies exploring their application. However, the majority of the previous research has relied on single case studies2–9. Consequently, conclusions on the wider implications for quality, economic and clinical impact have not been possible. This paper summarises 4 years of research into the application of DTs in soft tissue, extra-oral prosthetics. Technological capabilities have been critically evaluated in multiple case studies and a number of complementary experiments. The article presents conclusions on the current capabilities, limitations and future developments.
METHODS This research involved conducting a number of clinical case studies carried out through the Centre for Applied Reconstructive Techniques in Surgery (CARTIS). CARTIS is
a unique collaboration between The National Centre for Product Design & Development Research (PDR) and the Maxillofacial Unit of Morriston Hospital, Swansea (www.cartis.org). This collaboration provided clinical expertise and access to state of the art computer-aided product development technologies, such as 3D scanning, Computer-Aided Design and Rapid Prototyping. An Action Research (AR) approach was used in the implementation of the case studies. Case studies have been described as an “empirical inquiry that investigates a contemporary phenomenon within its real-life context”10. They are particularly useful when the boundaries between phenomenon and context are not clearly evident9. AR methods involve iterative stages of research design, research implementation and evaluation. Case study and AR methods are typically applied to the social sciences and involve techniques that are appropriate for studying “real life” situations where the researcher cannot control all of the variables or the research environment. Typically, these involve complex, changing situations and small samples. The participatory approach helps to produce realistic and valid results. A number of the case studies demonstrated the need to incorporate flexibility and adapt to unforeseen challenges. Throughout the research, a small number of complementary experiments were carried out to establish technical capabilities that informed subsequent case studies and did not require clinical investigation.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
9
RESULTS 1. Pilot Case Study – Orbital prosthesis This pilot study intended to utilise appropriate digital methods that had been identified in the literature and was subsequently published11. Digital Technologies utilised included Computed Tomography (CT), FreeForm Modelling Plus ComputerAided Design software (SensAble Technologies Inc.), and ThermoJet rapid prototyping (3D Systems Inc.). These were combined with conventional fitting and finishing techniques to produce the final prosthesis. This case demonstrated that CT data was sufficient to capture the facial anatomy, but it could not capture fine details such as texture and wrinkles. The case also indicated that FreeForm could be successfully used to design the basic shape of a prosthesis. The ThermoJet rapid prototyping process successfully manufactured the basic prosthesis design in a wax material that was shown to be suitable for modifying and moulding using conventional maxillofacial laboratory techniques. The wax prosthesis was therefore suitable for use in fitting sessions with the patient present (Fig. 1).
Fig. 2: A skin-like texture embossed on a surface in FreeForm CAD.
3. Case Study – Auricular prosthesis A A review of the literature identified that digital techniques had not been applied to the design of all of the components of a maxillofacial prosthesis. Therefore, this case study was designed to investigate how digital techniques could be used to produce a prosthesis design that incorporated magnetic retention (Technovent UK). The case study was published in 200614. This case explored the application of 3D scanning of a plaster replica of the patient’s defect site and contralateral ear (Steinbichler Optotechnik GmbH). Once again, FreeForm CAD and ThermoJet technologies were combined with standard hand finishing techniques. This study indicated that magnetic retention could be incorporated into digital prosthesis design. As with the pilot case study, modification of the wax prosthesis design was required using traditional techniques in order to achieve a satisfactory fit. Figure 3 shows the modified wax pattern.
Fig. 1: Trial fitting of the ThermoJet wax pattern following edge modification and ocular unit positioning.
2. Texture Experiment Rather than a case study, this experiment aimed to identify methods that were capable of capturing, utilising and physically reproducing convincing skin textures. This study was subsequently published in 200612,13. The experiment utilised a 3D scanning technology that a survey of available technologies had indicated would be capable of capturing texture as well as gross facial anatomical shape (Breuckmann GmbH). As in the pilot case study, FreeForm CAD (SensAble Technologies Inc.) and ThermoJet technologies were utilised. This experiment confirmed that FreeForm was capable of generating three-dimensional textures that could be incorporated into prosthesis designs. ThermoJet was found to be capable of physically reproducing fine textures that would produce a convincing skin texture. This experiment indicated that the optical scanning technology was limited in its ability to capture skin textures. Figure 2 shows a sample skin texture embossed on a compound, curved test surface in FreeForm.
10
Fig. 3: The modified wax pattern: a) trial fitted on the patient; b) the magnets incorporated directly into the wax pattern.
4. Case Study – Auricular prosthesis B This followed the previous case but explored the use of DTs in the design of bar and clip retention and was published in 200615. This project combined two 3D scanning technologies. Computed Tomography scan data was used to capture the contralateral ear whilst optical scanning of the
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
patient’s defect site was attempted (Konica-Minolta Vivid 900 laser scanner). Additionally, an alternative 3D scanning process was also used to scan a plaster replica of the defect site (Steinbichler Optotechnik GmbH). The ThermoJet process was used to produce a wax pattern of the ear prosthesis whilst Stereolithography (3D-Systems Inc.) produced the sub-structure incorporating the retentive clips. A new metal-based rapid prototyping process, Selective Laser Melting was utilised to produce the bar (SLM, MCPHEK GmbH). The computer-aided design of the components is shown in Figure 4. This study identified some significant limitations in the 3D scanning methods when attempting to capture data that would enable the design of implant retention components.
This study was also used to consider the economic implications of digital methods by measuring and comparing the design and construction times for each technique. Results suggested that reductions in the overall design and construction time were possible.
Fig. 5: a) The conventionally produced prosthesis. b) The digitally designed prosthesis.
6. Case Study – Direct RP production of bar
Fig. 4: CAD models of a scanned replica cast, bar, clip/sub-structure and auricular prosthesis form.
This experiment aimed to explore further digital design and direct manufacture of prosthesis retention bars. This case utilised touch probe scanning (Roland Pix–30), FreeForm CAD and Selective Laser Melting. Here, a new SLM machine specifically designed to produce small, accurate parts was used to manufacture the bar directly from CAD data (MCP-HEK GmbH, SLM–100). The bar produced was shown to be a good fit when attached to the replica cast abutments (Fig. 6).
5. Case Study – Nasal prosthesis This case explored the design and manufacture of a nasal prosthesis incorporating magnetic retention. The main purpose of the study was to apply the process knowledge obtained from the previous cases and compare them to entirely conventional methods. Technologies used included 3D scanning (Roland LPX–1200 desktop laser scanner, Roland DG Corp.), FreeForm CAD, Stereolithography (for the sub-structure) and ThermoJet (wax prosthesis pattern production). It was identified that there were significant differences in the quality that could be achieved by digital techniques (combined with conventional fitting and finishing) and entirely conventionally designed and manufactured prosthesis. This case demonstrated that digital methods (combined with conventional fitting and finishing) were capable of producing a clinically acceptable prosthesis. However, this was achieved using a 3D scan of the patients stone defect model rather than scanning the defect directly. This case demonstrated that there were no significant differences in the positional accuracy and shape achieved by both techniques. However, the digitally produced prosthesis was found to be significantly inferior in edge quality compared to the conventionally produced prosthesis.
Fig. 6: A digitally designed, SLM produced bar based upon a touch probe scan of a replica cast with abutments.
DISCUSSION The results of the case studies were used to consider three primary factors, quality, economic impact and clinical implications. Quality aspects included fit (marginal integrity of the prosthesis against the skin and fit between components), accuracy (anatomical position), resolution (reproduction of folds, wrinkles, texture, and substructure components), and materials (mechanical and chemical properties).
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
11
Fit Prosthesis fit was defined as the distance between the individual components and between the prosthesis margins and the anatomy. According to clinical best practice, there should be no visible gap between the prosthesis margin and the anatomy. When possible, the margin should form a seal that remains in contact with the skin during changing facial expressions and functions (talking, drinking, eating etc.). In conventional techniques, careful contouring of the wax pattern, modifying the mould and the inherent flash from the moulding process help to form extremely thin margins edges. These thin margins are soft and pliable enough to adapt to the skin surface and may maintain contact during facial movements. The thickness of fine margins produced using traditional techniques was measured to range from 40µm to 130µm. Best practice over many years has demonstrated that edges within this range achieve a good aesthetic result. The results of this research found that margins with a 260µm thickness could be achieved using FreeForm CAD. Whilst some RP technologies are capable of producing very thin layers, most could not produce parts in a suitable material. Whilst the ThermoJet process proved capable of producing patterns in an appropriate wax material, it was not able to reproduce edges thin enough to produce good margins and subsequent adaptation was required during moulding. When it comes to assessing the fit between components, what constitutes a ‘satisfactory’ fit has been discussed16–18. However, no conclusive method of evaluating passivity has been established. Clinical methods often rely on visually assessing movement in the frame (i.e. a rocker action). To be satisfactory a bar should be able to locate on two abutments without noticeable movement when pressed and there should be no visible gaps. Each stage in the process from data capture to bar manufacture introduces incremental errors resulting in an accumulation of tolerances. This creates difficulties when attempting to design and manufacture a bar that will fit abutments fitted to a patient. This was apparent from the findings from case study 4 indicated that designing bar structures was difficult when using data from optical scanners which produced insufficient data resolution. The use of a touch probe scanner to scan a plaster replica in case study 6 showed that improved results could be achieved. However, further studies are required to validate whether digital methods are capable of producing a clinically acceptable bar via rapid prototyping methods.
Accuracy Assessing the accuracy of a maxillofacial prosthesis is subjective but can be considered according to two criteria, accurate location in relation to the contralateral appearance and the positional accuracy in relation to anatomical landmarks.
12
Conventional methods require the patient to attend clinics so that measurements can be taken. These typically involve the use of rulers, callipers and protractors to assess the position of a prosthesis. The aim is always to locate the prosthesis to produce a convincing visual appearance and these measurements are used to assist location in conjunction with visual inspection. Digital methods enabled location to be manipulated and adjusted at will any number of times without necessarily having the patient present. This alone may provide a number of advantages for both the patient and prosthetist in terms of number and duration of clinics, reduced travel and flexibility in the prosthetist work scheduling. In addition, it was noted that the use of digital methods enabled angles of view and sectional views to be used that would be impossible or at least extremely difficult to achieve when dealing with the actual patient. Due to the subjective nature of assessing facial appearance it is very difficult to define quantifiable standards of fit. However, the case studies undertaken resulted in prostheses with good location and produced results as good as would be produced when using conventional techniques.
Resolution and texture Conventional techniques utilise impression techniques to transfer existing textures and fine details from the patient onto the prosthesis. These techniques, typically using silicone materials produce an extremely faithful reproduction of small features. Digital Technologies however rely in data points to describe three-dimensional shapes. The number of data points per unit area is a variable that is entirely dependent on the technology being used. The cases illustrated that many scanning technologies can provide a sufficient density of data points to adequately describe overall anatomical shape. Whilst CT, laser and structured white light scanning were found to describe overall anatomical shape adequately they were very limited in their ability to record small facial features such as folds, wrinkles and skin texture. In addition, the case studies indicated that these scanning technologies also had difficulty in capturing implant abutments, which made scanning defect sites incorporating abutments problematic. Touch probe scanners were shown to be able to capture sufficiently dense data points to capture abutments but these are not capable of scanning the patient directly. The case studies showed that combining conventional impression and replication techniques and using touch probe scanners to digitise the replicas could produce sufficiently good data to enable the design of an implant retained prosthesis using digital techniques. As an alternative to recording the patient’s skin textures, experiment 2 demonstrated that digital techniques could be used to create and reproduce appropriate details such as skin texture and wrinkles12,13. The results of experiment 2 suggested that in order to capture, describe and reproduce convincing skin texture DTs must be capable of working to resolutions around one point per 0.03mm in all axes. However, whilst the experiment was successful on small samples the amount of data required was very large. Scaling this data requirement to a whole prosthesis, particularly one
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
covering a large area would require such large data files that current technologies would struggle to cope. This is compounded by the fact that many rapid prototyping technologies rely on the STL file format, which is quite inefficient when describing highly detailed surfaces. Whilst the rapid development of computer capability will increase to meet this challenge, there is also scope for the development of more efficient data file formats. Whilst the suitability of available rapid prototyping technologies for prosthetics has other requirements, most notably material properties, the ability to reproduce fine details such as skin texture is also an issue. Experiment 2 demonstrated that the ThermoJet process was capable of reproducing skin textures in the range 0.1mm to 0.8mm. In order to reproduce texture details on a prosthesis pattern, RP technologies must have the ability to build in the 10s of microns level. Whilst some RP technologies are approaching this level of detail, the materials they use are not compatible with current prosthetic techniques.
Retention Retention is typically achieved using gold bar and clips or magnets. Bar and clip methods provide higher retentive forces and the retention strength can be altered by adjusting the compression of the clips or increasing the number of clips. Attempts to incorporate retention clips into substructures manufactured using RP techniques proved unsuccessful. The materials used in the case studies provided retention, but the retention strength was poor and they wore rapidly reducing retention strength still further. As prostheses are likely to be applied and removed twice a day, a twelvemonth period equates to 1,460 cycles of the retentive components and the case studies indicated that the RP clips incorporated into the substructures would not provide a sufficient service life. The bars must also be able to withstand the force of application and removal. Due to their small size, a relatively stiff, typically metal material is required. Gold is typically used, but biocompatible alloys such as Cobalt-Chrome or Titanium, are viable alternatives. The availability of metal RP processes enabled the investigation of direct digital manufacture of retention bars. Bars were attempted using 316L Stainless Steel and Cobalt-Chrome. Experiment 6 and published literature in similar applications have shown that Selective Laser Melting can be used to manufacture bar components15 and that they may also be successfully cast from Stereolithography patterns19. Silicone has long been acknowledged as the optimum material for the body of the prosthesis. It has excellent physical properties and can be colour-matched to produce a highly convincing visual appearance. Currently no RP technology is capable of producing a prosthesis with the required properties. In these cases, wax patterns were produced that were successfully incorporated into the conventional prosthetic production process.
Economic impact Digital techniques can potentially have direct, indirect and opportunity impacts. Direct costs are associated with the cost of care, treatment, materials, etc. Indirect economic costs are associated with technology costs (purchasing, maintenance) and overheads. Opportunity costs are those costs that could be accrued from alternative approaches to those taken. This can be associated with both the delivery of treatment and for the patient. Treatment opportunity costs could be represented by missed appointments, longer clinics, etc. Opportunity costs for the patient could include lost earnings, travel time, overnight stays, etc. This was an area of particular interest since previous publications and advocates of DTs suggest that their application can lead to reduced production times. A detailed comparison of the time and cost implications of the implementation of the digital techniques is shown in the flowchart in Table 1. The detail was gathered from timed cases and techniques used in the case studies were judged to be clinically viable in the near future. The flowchart shows the stages, staff and resources required for prosthesis construction and it indicates the economic opportunities and additional indirect costs associated with the introduction of DTs. Economic impacts are difficult to measure and quantify because cases vary from patient to patient and costs vary regionally. In addition, many costs are hidden in overheads and fixed costs. Whilst the cases indicated that DTs might produce economic benefits, more work is needed to establish that the benefits are widely achievable and significant. However, the cases indicated that many of the benefits are represented by opportunities. The case studies suggested that given current circumstances the investment required would probably not yield sufficient time savings to make economic sense. Considering that a major regional Maxillofacial Unit in the UK will fabricate approximately 10 to 20 new facial prostheses per year (in personal communications with Maxillofacial Labs at Morriston Hospital, Queen Victoria Hospital and Queen Elizabeth Hospital in the UK), the return on investment would be poor. A strategy for addressing this issue is to invest in technologies that have wider applications within a hospital would help to spread the investment costs. For example, 3D scanning technologies may also be used to assist in burns splint fabrication or craniofacial surgery planning. CAD and CT data preparation software could also be used to in computer-aided surgical planning, implant design and the design of custom-fitting surgical guides and templates.
RECOMMENDATIONS 3D Scanning Where available, use of CT data obtained pre or postoperatively should be used. This may remove the need to scan the anatomy using optical methods and assist in the design stage by providing a form based on the patients original anatomy.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
13
Table 1: Cost implications of the implementation of the digital techniques Conventional stage
People involved
Direct resource costs
Digital economic opportunity
Addition indirect costs of digital technology
Patient consultation
Patient Surgeon Prosthetist Nurse Receptionist
Clinic room Waiting room
No difference
No difference
Impression taking
Patient Prosthetist
Lab and clinic room
Reduced time if patient is scanned directly instead
Scanner hardware. Additional time if indirect scanning of a cast is required
Create stone replicas
Prosthetist
Lab
Possible stage removal – reduced time
CAD software
Bar/substructure design and fabrication
Prosthetist
Lab
Free up lab space
CAD software. Additional RP fabrication time and cost
Hand carve pattern
Prosthetist Patient for final fitting of pattern
Lab and clinic room
Reduced design time. Removal of patient: – No travel time – Capacity to work/go to school – Removal of potential non-attendance – Free up clinic space
CAD software. Additional RP fabrication time and cost
Flasking of pattern
Patient Prosthetist
Lab and clinic room
No difference
No difference
Boil out pattern and mould clean up
Prosthetist
Lab
No difference
No difference
Colour matching
Prosthetist Patient
Clinic room
No difference
No difference
Curing time
None
Lab
No difference
No difference
Removal from mould, fitting and extrinsic colouring
Prosthetist Patient
Lab and clinic
No difference
No difference
Where adhesive retention is used, the anatomy is simpler to capture since there are fewer undercuts caused by retentive components blocking the scanners line of sight. Where the nose is missing, the reflective mucosal layer is unlikely to capture well, but this will not affect the subsequent design stages as long as the margins are captured in detail and without distortion. It is particularly difficult to capture behind the ear, which may make it necessary to take an impression and scan a replica cast of the contralateral ear. A significant advantage of using non-contact scanning methods is that that the eyes can be captured whilst open. This allows details from the unaffected side to be mirrored to form the basis of the prosthesis design. The eye globe is unlikely to capture accurately due to its reflectivity and translucency. The fine detail and reflective surfaces of implant retention components makes them difficult to capture using optical based scanning technologies. This may be addressed by applying a light coloured, matt, opaque coating. However, due to the accuracy and resolution limitations of current light-based scanners it has been shown to be more productive to produce a replica cast of the defect site. The advantages of this approach are that the replica can be kept perfectly still and held at any angle desired. This enables slower but more accurate scanning technologies to be used, including light-based or touch probe scanners. The replica can be covered in a matt white powder to improve scanning without inconvenience to the patient.
14
Prosthesis Design FreeForm CAD has been demonstrated to be the most appropriate CAD tool for prosthesis design in all of these case studies and also in previously published literature7, 8, 11–15. It has been shown to be the most appropriate way to manipulate anatomical forms and is also comparatively intuitive for prosthetists to learn to use. When considering the investment required, research has shown that FreeForm can be used in many other applications in the maxillofacial lab in other ways including: cranioplasty contouring20, creating burns pressure splints21, surgical guide design22 and removable partial denture framework design19–28.
Fabrication ThermoJet 3D printing has been shown to be suitable for physically producing wax prosthesis patterns. The wax material, although not exactly the same as the wax typically used in the lab, can be altered using conventional lab techniques. The process is comparatively rapid, requires minimal clean up, is easy to use and has been shown to be able to produce patterns with skin textures. Conventional production of the final prosthesis body in silicone still represents the only, clinically viable option.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
Patient and Prosthetist
Prosthetist
Patient and Prosthetist
Table 2: Workflow based on the current capabilities of digital technologies in the design of a magnet-retained prosthesis
Stage
Details
Patient consultation
As per conventional methods
Place the matt coated magnets on the abutments
Coat the magnets in a matt, light coloured finish to reduce the reflectivity
Non-contact scan the patient
Scan, capturing the entire sub-structure surface and area of face required to undertake the design
l l l l
Process scan data
Fill holes and remove noise if required
Design the pattern and sub-structure if required
Use FreeFrom to design the prosthesis form and sub-structure (where required for magnet-retained cases)
Fabricate the pattern and sub-structure
Use ThermoJet printing to produce the pattern. Use Stereolithography or alternative RP proces to produce the sub-stucture in a suitable resin-based material
Try the pattern on Refine the pattern
As per conventional methods
Flask the pattern Undertake colour matching Pack mould and cure the silicone Remove the prosthesis and trim
Note: the patient may or may not be in attendance during flasking and silicone curing. This will depend if the prosthesis can be completed in a single day. If not, either of these processes may be undertaken without the patient present
Extrinsic colour and detailing
Selective laser melting has demonstrated potential to produce bar structures, but further research is required to validate the dimensional accuracy, material compatibility and clinical viability. Sub-structures and base plates may be fabricated using Stereolithography. Other RP processes such as Perfactory Digital Light Processing or Objet three-dimensional printing, ideally in a polymer material with a flexural modulus equal to, or greater than 1,720 MPa (value of DSM Somos 10110, epoxy Stereolithography resin) also show potential.
ILLUSTRATION OF THE CURRENT STATE OF THE ART USING DIGITAL TECHNOLOGIES In order to attempt the digital design and fabrication of maxillofacial prostheses the following technologies are required. l
l
3D Scanner to capture the facial anatomy (light-based).
Software to process scan data and output-good quality STL data. Software to process CT data and convert to good quality STL data. Haptic sculpting CAD software to design the prosthesis body and sub-structure. Wax printing RP technology to produce the prosthesis pattern. RP technology to produce stiff sub-structure components.
Table 2 illustrates the workflow possible with current DTs in the design and fabrication of magnet-retained prostheses.
CONCLUSIONS Hospitals and Universities undertaking research in DTs are driving developments and improving accessibility leading to wider application. However, whilst some units are exploring the application of DTs, access remains limited. Further research is required to develop technologies that are more affordable and easier to use. The research has highlighted the fact that DTs have not been developed towards the needs of maxillofacial prosthetics, which may hinder adoption further. Introducing DT to training courses and integrating them better with the whole treatment process may help to improve their adoption into hospital laboratories and clinics. It is clear that DTs have enormous potential. However, the cases summarised here have illustrated that although DTs can be successfully applied to many aspects of prosthesis construction, they are not yet sufficiently well developed to design and manufacture maxillofacial prostheses efficiently. For example, 3D scanning does not yet offer sufficient resolution to capture fine texture detail over an entire face. Although FreeForm has been shown to be a suitable design technology, issues remain when combining geometric components with anatomical data. In addition, it is not yet possible to assign skin colours necessary for a facial prosthesis in this CAD environment. Despite the success of producing prosthesis components and wax patterns achieved in these cases, the application of DTs will be restricted by the lack of any technology capable of building a colour matched, silicone prosthesis body. In addition to the technical limitations of DTs, the case studies indicated that in their current state they do not make a convincing economic case on the grounds of increased speed or efficiency. It is likely that until costs come down significantly DTs would only be viable for large, busy units where other applications could also be found.
References 1. Wolfaardt J., Sugar A., Wilkes G. Advanced technology and the future of facial prosthetics in head and neck reconstruction, Int J Oral Maxillofac Surg. 2003; 32(2): 121–3. 2. Chen L.H., Tsutsumi S., Iizuka T. A CAD/CAM technique for fabricating facial prostheses: a preliminary report. Int J Prosthodont. 1997; 10(5): 467–72.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
15
3. Bibb R., Freeman P., Brown R., Sugar A., Evans P., Bocca A. An investigation of three-dimensional scanning of human body surfaces and its use in the design and manufacture of prostheses. Proc Inst Mech Eng [H]. 2000; 214(6): 589–94. 4. Chua C.K., Chou S.M., Lin S.C., Lee S.T., Saw C.A. Facial prosthetic model fabrication using rapid prototyping tools. Inte Manufac Sys. 2000; 11(1): 42–53. 5. Cheah C.M., Chua C.K., Tan K.H., Teo C.K. Integration of laser surface digitizing with CAD/CAM techniques for developing facial prostheses Part 1: Design and fabrication of prosthesis replicas. Int J Prosthodont. 2003; 16(4): 435–41. 6. Cheah C.M., Chua C.K., Tan K.H. Integration of laser surface digitizing with CAD/CAM techniques for developing facial prostheses Part 2: Development of molding techniques for casting prosthetic parts. Int J Prosthodont. 2003; 16(5): 543–8. 7. Verdonck H.W.D., Poukens J., Overveld H.V., Riediger D. Computer-Assisted Maxillofacial Prosthodontics: A new treatment protocol. Int J Prosthodont. 2003; 16(3): 326–8. 8. Sykes L.M., Parrott A.M., Owen P., Snaddon R. Applications of rapid prototyping technology in maxillofacial prosthetics. Int J Prosthodont 2004; 17(4): 454–9. 9. Chandra A., Watson J., Rowson J.E., Holland J., Harris R.A., Williams D.J. Application of rapid manufacturing techniques in support of maxillofacial treatment: evidence of the requirements of clinical application. Proc Inst Mech Eng [B]. 2005; 219(6): 469–76. 10. Yin R.K. Case study research: Design and methods, 3rd ed., Sage Publishing. 2003. 11. Evans P., Eggbeer D., Bibb R. Orbital Prosthesis wax Pattern Production using Computer-Aided Design and Rapid Prototyping Techniques. J Maxillofac Prosthet Tech. 2004; 7: 11–5. 12. Eggbeer D., Evans P., Bibb R. A pilot study in the application of texture relief for digitally designed facial prostheses. Proc Inst Mech Eng [H]. 2006; 220(6): 705–14. 13. Bibb R. Medical modelling: the application of advanced design and development technologies in medicine. Woodhead Publishing Ltd., Cambridge, UK, 2006. ISBN: 1–84569–138–5, 262–75. 14. Eggbeer D., Bibb R., Evans P. Assessment of digital technologies in the design of a magnetic retained auricular prosthesis. J Maxillofac Prosthet Tech. 2006; 9: 1–4. 15. Eggbeer D., Bibb R., Evans P. Towards Identifying specification requirements for digital bone anchored prosthesis design incorporating substructure fabrication: a pilot study. Int J Prosthodont. 2006; 19(3): 258–63.
17. Jemt T. Failures and complications in 391 consecutively inserted fixed prostheses supported by Brånemark implant in the edentulous jaw: a study of treatment from the time of prosthesis placement to the first annual check up. Int J Oral Maxillofac Implants. 1991; 6(3): 270–6. 18. Kan J.Y., Rungcharassaeng K., Bohsali K., Goodacre C.J., Lang B.R. Clinical methods for evaluating implant framework fit. J Prosthet Dent. 1999; 81(1); 7–13. 19. Eggbeer D., Bibb R., Williams R. The Computer-Aided Design and Rapid prototyping of Removable Partial Denture Frameworks. Proc Inst Mech Eng [H]. 2005; 219(3): 195–202. 20. Bibb R., Bocca A., Evans P. An Appropriate Approach to Computer-Aided Design and Manufacture of Cranioplasty Plates. J Maxillofac Prosthet Tech. 2002; 5(1): 28–31. 21. Bibb R., Bocca A., Hartles F. “Producing Burns Therapy Conformers Using Non-Contact Scanning and Rapid Prototyping” Proceedings of the 6th International Symposium on Computer Methods in Biomechanics & Biomedical Engineering, Madrid, Spain, February 2004. ISBN: 0–9549670-0–3 (Published on CD-ROM by First Numerics Ltd. Cardiff, UK). 22. Bibb R., Eggbeer D., Bocca A., Sugar A., “Rapid design and manufacture of custom fitting stainless steel surgical guides”, in 6th National Conference on Rapid Design, Prototyping & Manufacture, eds Bocking C.E., Rennie A., Jacobson D. 2005, CRDM/Lancaster University, 65–72. 23. Williams R.J., Bibb R., Eggbeer D. CAD/CAM in the Fabrication of Removable Partial Denture Frameworks: A Virtual Method of Surveying 3D Scanned Dental Casts. Quintess J Dent Tech. 2004; 2: 268–76. 24. Eggbeer D., Williams R.J., Bibb R. A Digital Method of Design and Manufacture of Sacrificial Patterns for Removable Partial Denture Metal Frameworks. Quintess J Dental Tech. 2004; 2: 490–9. 25. Bibb R., Eggbeer D., Williams R. Rapid manufacture of removable partial denture frameworks. Rap Proto J. 2006; 12(2): 95–9. 26. Williams R.J., Bibb R., Eggbeer D., Collis J. Use of CAD/CAM technology to fabricate a removable partial denture framework. J Prosthet Dent. 2006; 96(2): 96–9. 27. Williams R.J., Bibb R., Eggbeer D., Woodward A. A Patient-fitted removable partial denture framework fabricated from a CAD/CAM-produced sacrificial pattern. Quintess J Dent Tech. 2006; 4(3): 200–4. 28. Bibb R.J., Eggbeer D., Williams R.J., Woodward A. Trial fitting of a removable partial denture framework made using computer-aided design and rapid prototyping techniques. Proc Inst Mech Eng [H]. 2006; 220(7): 793–7.
16. Brånemark P.I. Osseointegration and its experimental background. J Prosthet Dent. 1983; 50: 399–410.
16
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
FLEXIBLE JAW EXERCISER: AN ALTERNATIVE APPLIANCE FOR TRISMUS REHABILITATION C. Orbaneja Botija Carmen Orbaneja Botija MIMPT Maxillofacial Prosthetics Service Poole Hospital NHS Trust Longfleet Road Poole Dorset BH15 2JB
This paper highlights the importance of mouth opening recovery in patients who do not tolerate the hardness and/or shape of a conventional trismus appliance. The construction of a flexible jaw exerciser as an economical and straightforward to produce device for temporo-mandibular joint problems was considered to be a treatment alternative. A protocol form and patient information leaflet were written to establish an accurate and easy to follow treatment. Keywords: Trismus, Flexible jaw exerciser, Protocol, Information leaflet.
INTRODUCTION
AETIOLOGY
Trismus is defined as a contraction of the mastication muscles which generates restriction of mouth opening1. It can occur immediately post surgery involving the maxilla or mandible and post radiotherapy at any time. Early treatment can minimise complications, with prophylactic management in appropriate cases further reducing the number of patients experiencing this condition.
A lack of success using conventional trismus screws or tongue depressors in patients groups (including those who have had an maxillectomy, some edentulous patients, gingival problems and post-radiotherapy), led to the requirement for an alternative device in the Department of Maxillofacial Prosthetics in Poole Hospital NHS.
The diagnosis is often overlooked by a number of professionals as it is not life threatening, and unless informed pre-operatively, patients may assume that the mouth opening reduction is ‘normal’ and will recover with time. Unfortunately, the trismus is likely to worsen if not treated, with immobile joints suffering degenerative changes1.
In post radiotherapy patients, the tissue is particularly sensitive and may not tolerate a hard surface against it with even minimal pressure. The TheraBite appliance has been shown to be beneficial in this group of patients, but it is relatively expensive (£221.43 per device)3.
A study from Boston reported that the normal maximum mouth opening is 48.9mm, which may be assessed by positioning three fingers vertically aligned between the upper and the lower central incisors up to the first distal interphalyngeal folds2. Trismus can be caused by trauma, nerve damage, radiation treatment, TMJ problems, central nervous system dysfunction or a combination of them1. The passive motion of using a jaw exerciser allows the TMJ to stay relaxed, while the device moves the joints by increasing mouth opening. The jaw exerciser keeps the joints healthy without activating painful muscles and reduces TMJ inflammation and muscle pain1.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
Fig. 1: Photographs of tongue depressors, acrylated Trismus screw and a TheraBite4.
17
The flexible jaw exerciser can also benefit patients undergoing radiotherapy. It is advisable to monitor for trismus by checking for pain or weakness in the masticating muscles in the radiation field. Problems can arise as a result of collagen deposition causing further tissue fibrosis5. The patients can also be instructed to prophylactically exercise the muscles of mastication 3 times daily, opening the mouth as much as possible without pain, 20 times, without the need of any appliance6. Contraindications to the use of the flexible jaw exerciser include: l l l
Patients with new skin flaps in the area of application of the exerciser. Patients with possible fracture in the maxilla, mandible or any weaknesses of the surrounding bones. Patients with osteoradionecrosis of the jaw or infections including osteomyelitis7.
PROBLEMS CAUSED BY TRISMUS 1. Maxillofacial Difficulty in re-examination leading to problems in diagnosing recurrent disease. Complicated management of surgical site: surgery itself, impression taking, obturation of the defect area, rehabilitation.
2. Dietetics Reduced mouth opening can result in reduced oral intake, weight loss and considerable nutritional deficit, which can compromise the recovery from surgery, radiotherapy and/or chemotherapy. It may also make mastication more complex as a result in a compromised airway clearance1.
3. Speech and Language Reduced mouth opening can impact speech with a decreased size of the resonating oral cavity reducing the quality of the voice1.
the prescribed treatment routine. Trismus if untreated can worsen and affect the quality of life due to difficulty in daily tasks such as speech, mastication, taste and hygiene. Patient’s mental strength may weaken, making the overall recovery slower, especially for those who have received or are currently receiving radiotherapy.
MATERIALS AND METHODS A master model was fabricated in lab putty which could be trimmed easily and quickly, using a grinder to give flat surfaces. The wedge with a handle had a narrow section of 10mm to accommodate patients who had a much decreased mouth opening (up to 13mm). According to the Boston study previously mentioned in the introduction, it was decided to construct the widest section at 50mm. Vertical lines were incorporated on one side every 10mm so the patient could easily assess the mouth opening during the treatment. These lines were made with a saw and round blade in the lab putty master model. A mould of the putty master model was made using a metal flask, Crystacal R hard plaster and the conventional two part mould technique and separating agent. Once the plaster was set, the master model was removed and the void filled with an addition cure silicone (more commonly known as Platinum cure silicone) while either dermatologically tested or medical grade silicone were used to avoid any reaction when in contact with tissue. The silicone was mixed with a standard catalyst along with a thixotropic agent for easy control when transferred into the mould, adding white pigment Factor II 9. The types of silicone used for the construction of these appliances were: l l
Elastomer 42 by Technovent whose shore hardness is A42 with the Factor II thixotropic agent A 300-810. Maxillofacial Rubber M511 with hard catalyst M516 by Cosmesil whose shore hardness is A35-40 with anti slump agent M514.
When cured, the silicone wedge was removed from the mould and minor trimming was carried out.
4. Dentistry Oral hygiene could be compromised, leading to dental caries and/or infection if not treated. The situation worsens by the difficulty in placing dental restorations and doing extractions8.
5. Cosmesis Cosmetic appearance while talking may change because of opening restrictions.
6. Psychology The discomfort and occasional bleeding of the tissue when using hard trismus screws or tongue depressors may demotivate patients. This may result in poor compliance of
18
Fig. 2: Photograph of a flexible jaw exerciser4.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
The flexible jaw exerciser was provided together with a flexible plastic ruler so that the patient could measure the opening weekly. This was also made in the laboratory by copying and pasting a 50mm long ruler on an A4 sheet which was used to make an acetate copy. Then it was trimmed to obtain individual rulers.
CONCLUSION l
l
Awareness of trismus and its prophylactic treatments could minimise the number of patients affected by it. Improvement in mouth opening can be related to the patient compliance.
Each flexible jaw exerciser was customised to the patient needs in terms of opening, shape and material used.
l
PROTOCOL AND PATIENT INFORMATION LEAFLET
Acknowledgements
(Both enclosed as appendix at the end of this paper)
I would like to thank the following colleagues:
A protocol was filled out and signed by either a consultant or a specialist registrar. Specified application of heat on the affected area before or after the treatment11 instructions of how to use the device, type of treatment recommended, storage, modifications and cautions would be given verbally as well as written. A patient evolution record chart was also provided and the patient was asked to bring it to every appointment with the prescriber as a method of encouragement to follow the treatment, which may be long and seem tedious.
Mr Mark Townend, Maxillofacial Prosthetist Head of Service, and Mrs Heidi Silk, Principle Maxillofacial Prosthetist, both at Poole Hospital NHS Trust for their constant support not only in this paper.
Initial opening was measured and recorded at the start of the jaw exerciser treatment. A patient information leaflet was provided, in which basic definition of trismus, its problems and how and when to use the flexible jaw exerciser were described. Patients should be followed up closely, ensuring the correct frequency and adequate procedure of its use. This allows early identification of any problems due to misuse of the device.
RESULT Cosmesil Maxillofacial Rubber M511 with hard catalyst has been selected for the construction of future flexible jaw exercisers as patients found it softer, more comfortable and more compliant with the therapy. The flexible jaw exerciser can be particularly helpful when used in conjunction with the written protocol. Patient progress records as well as periodic reviews (of 1 to 2 weeks) were beneficial in encouraging patients to follow the prescribed treatment. Patient information leaflets could facilitate the rehabilitation process by ensuring adequate awareness of the condition and allowing treatment to be conducted accurately.
Information and follow up was considered to enhance patient co-operation.
Mr Parkash Ramchandani, Consultant Oral and Maxillofacial/Head and Neck Surgeon at Poole Hospital NHS Trust for his collaboration in this paper. Mrs. Penny Scott, Senior Specialist Speech and Language Therapist and Miss Abbie Smith, Specialist Speech and Language Therapist, Poole Hospital NHS Foundation Trust. Miss Pamela Cartwright, Oncology Dietician, Poole Hospital NHS Foundation Trust.
References 1. What is Trismus? 1–4 www.oralcancerfoundation.org/dental/trismus.htm © 2001–2007, OCF Inc. 2. Zawawi K.H., Al-Badawi E.A., Lobo Lobo S., Mellis M., Mehta N.R. 0873 An Index for the Measurement of Normal Maximum Mouth Opening. Tufts University School of Dental Medicine, Boston, MA, USA. March 2000 Available at http://iadr.confex.com/iadr/2002SanDiego/ techprogram/abstract_16576.htm 3. Information obtained by ATOS medical representant during a telephone conversation on 05/01/2007. 4. Pictures taken by Medical Photography at Poole Hospital NHS Trust. 2007. 5. Srithavaj T., Thaworanunta S., Bunnang J. Modified denture plates using bilateral technique manipulation in trismus-induced head and neck irradiated patients: A pilot study. Mahidol Dent J 2006; 26: 229. Available at http://www.dt.mahidol.ac.th/eng/eresources/journal/PDF26 (3)/DENT26(3)227.pdf 6. National Institute of Dental and Craniofacial Research. Oncology Reference Guide to Oral Health. 1. Available at http://www.nidcr.nih.gov/HealthInformation/ DiseasesAndConditions/CancerTreatmentAndOralHealth/ OncologyReferenceGuide.htm This information is not copyrighted. Updated Jul. 2002.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
19
7. Atos Medical. Treatment Regimens. Available at http://www.atosmedical.com/Products/Mouth_Jaw/ The_TheraBite_System/Treatment%20Regimens.aspx. Updated Nov. 2006. © 2006 Atos Medical. 8. Thomas D. Taylor. Clin Maxillofac Prost. 43. © 2000 Quintessence Publishing Co, Inc.
10. Technovent Product Catalogue 2007; 10–11. www.technovent.com 11. Peters W.J. Consultant. Poole Hospital NHS Trust. Patient Information Leaflet: Training to Obtain Correct Jaw Function. Reviewed 01/2007.
9. Thomas K.F. Techniques and Materials Guide for Successful Facial and Somato Prosthetic Rehabilitation. 164. © 2006 K.F. Thomas.
20
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
APPENDIX 1 PATIENT INFORMATION LEAFLET WHAT IS THE JAW EXERCISER? The Jaw Exerciser is a device that may be supplied to you to help increase the amount your mouth opens if this becomes more difficult than normal.
Your Specialist will advise that you start jaw exercising and one of the team will then discuss and demonstrate the treatment to you. A device and printed instructions will be given to you and your mouth opening will be measured when you start the treatment and as you continue.
WHAT IS TRISMUS?
What the Jaw Exerciser should and should not do
It is a restriction of mouth opening because the lower jaw is not functioning as normal. Various things can lead to trismus including:
The Jaw Exerciser should apply constant pressure when you use it. You will be advised to undertake daily regular constant sessions.
• • • • • • •
The Jaw Exerciser should not cause you pain as this can cause an opposite effect and make the trismus worse.
Trauma. Radiation therapy. Surgery. Stroke. Extraction of the wisdom teeth. Problems with the joint of the lower jaw. A combination of the above.
WHAT ARE THE PROBLEMS THAT TRISMUS CAN CAUSE? If your mouth cannot open normally it may not be able to create normal sounds and therefore you may find it difficult to speak. Reduced mouth opening can also cause problems with things such as: • • • • •
Eating. Tooth brushing. Putting in and taking out dentures. Specialist dental examinations and treatments. Cosmetic appearance whilst talking.
Overall the problem of trismus can be an added stress to you when you are already undergoing other treatment.
THE TREATMENT OF TRISMUS The Jaw Exerciser The majority of patients can use a Jaw Exerciser although the design of the device may vary depending on your particular situation, i.e. if you have some teeth missing. To avoid the problems described it is best to start jaw exercising as soon as your Specialist is happy that it is safe for you to do so, i.e. not immediately after your operation.
The Jaw Exerciser should allow the joint of your lower jaw to be relaxed but moving as the Jaw Exerciser opens your mouth.
Success with the Jaw Exerciser Success with the Jaw Exerciser is achieved by using it regularly over a period of time, i.e. weeks not days. You will be shown how to monitor your own progress with a simple measure and regular review appointments will be arranged for you, normally when you are due to see the Head and Neck Team anyway. You will need to continue using the Jaw Exerciser until advised otherwise by the Team or your trismus may return.
Problems with the Jaw Exerciser If during the treatment you notice any of the following, please stop the treatment immediately and contact the Head and Neck Team, details are on the cover of this leaflet: • • • •
Redness/itching of your skin/gums – Allergy. Prolonged discomfort/pain. Swelling of your mouth or neck. Sensitivity of your teeth/gums.
For more detailed information Oral Cancer Foundation www.oralcancerfoundation.org/dental/trismus.htm National Institute of Dental and Craniofacial Research www.nidcr.nih.gov
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
21
The Journal of Maxillofacial Prosthetics & Technology
TS IS
TE ITU ST IN
ISTS & TECHN OL HET ST OG RO
OF MAXILLO FAC IA L
P
TH E
APPENDIX 2 THE JAW EXERCISER: PROTOCOL FORM Treatment Advised
Notes
Type of Jaw Exerciser Plastic trismus screw n
•
Flexible Jaw Exerciser
Treatment recommended: 8-5-8-7
n
30-5-5-5
n
n
n Other (please specify) __________________________
Application of heat on the affected area Yes
Before treatment n During treatment After treatment n Duration of heat application 10 minutes 5 minutes n Consultant
n
SPR
n
n
n
n No n
15 minutes
Other n
•
If you have been supplied with a flexible Jaw Exerciser, push it in after it has been positioned in the centre of the mouth. If you have been supplied with a plastic trismus screw, rotate it round instead of pushing it in.
OTHER TREATMENT RECOMMENDED: ___________________________________________ Storage
n
Wash the Jaw Exerciser after every session with warm water and washing up liquid and dry it. Store it in a dry environment. Do not expose to high temperatures.
Name _________________________________________
Modifications and replacements
Title ________________________ Date_____________
These devices can be modified as required i.e. made shorter as your mouth opening increases.
INSTRUCTIONS Your mouth opening will be measured and recorded before starting the treatment. You will be able to monitor your own progress by using the ruler provided and filling in the Patient Progress Record on this form. When and how to measure will be demonstrated to you.
Treatment for patients with limited jaw mobility: 8-5-8-7 • • • • • • •
Sit with your head straight. Place the Jaw Exerciser in the centre of the mouth until the muscles are stretched. Avoid bringing your lower jaw backwards. Maintain this position for 8 seconds. Rest for 5 seconds. Repeat this exercise 8 times per session. Perform 7 sessions a day.
Treatment for patients with jaw pain: 30-5-5-5 • • • • • • •
22
Replacement due to loss or breakage is provided, as continuous rehabilitation is very important. Please contact the Team.
Cautions The Jaw Exerciser is only for your use, please handle it with care. If you notice any of the following, please stop your treatment and contact the Team, details are on the cover of this form: • • • •
Redness/itching of your skin/gums – Allergy. Prolonged discomfort/pain. Swelling of your mouth or neck. Sensitivity of your teeth/gums.
Patient Progress Record Date
Time
Measurement of Period jaw opening of time Before
Comments (ie. pain, swelling…)
After
Sit with your head straight. Place the Jaw Exerciser in the centre of the mouth until the muscles are stretched. Avoid bringing your lower jaw backwards. Maintain this position for 30 seconds. Rest for 5 seconds. Repeat this exercise 5 times per session. Perform 5 sessions a day.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
EXTERNAL HOLLOW BUTTOCK PROSTHESIS P. Kaur and D. Coppins Paramjit Kaur BSc (Hons) MIMPT Maxillofacial Prosthetist Craniofacial Prosthetics Unit Dental Institute Kings College Hospital NHS Foundation Trust Bessemer Road London SE5 9RS
David Coppins BSc (Hons), LCGI, MIMPT Consultant Anaplastologist Department of Anaplastology Burns, Plastic Surgery and Oral Directorate Sheffield Teaching Hospitals Foundation NHS Trust Northern General Hospital Herries Road Sheffield S5 7AU
Introduction: This paper describes a methodology for the fabrication of a custom-made external hollow buttock prosthesis for a burns patient, and details the treatment options and the selected choice of treatment. Method: An impression of the defect was taken and a wax-sculpt pattern shaped and fitted to assess the conformity of functional movements. A mould was prepared, allowing for the void in the wax pattern and packed with a silicone elastomer. Conclusion: The prosthesis allows the patient to walk and sit comfortably and gain confidence by wearing the external hollow buttock prosthesis for a successful outcome. The advantages of the custom-made external hollow buttock prosthesis over a conventional solid prosthesis are that it fits very well to the patient’s skin, the prosthesis was not visible and it was light in weight. Being non-invasive the procedures avoid surgical and multiple surgical reconstruction. This case was undertaken at the Department of Anaplastology and Maxillofacial Surgery at the Northern General Hospital in Sheffield. Key: buttock prosthesis, hollow, burns, rehabilitation of patient.
INTRODUCTION An external buttock prosthesis maybe used in the prosthetic rehabilitation treatment of congenital deformities or syndromes, burns, trauma and tumour excision. The management of burns to the buttock area are difficult because of difficulty in securing the dressings, risk of faecal soilage leading to wound infection and poor graft take. Potokar et al1 states that isolated buttock burns are often superficial, they consist of a different aetiology in adults and children and are often a result of contact burns. Burns from hot water scalds are usually superficial partial thickness or full thickness burns and they require treatment. The current available treatments for burns in the buttock area are grafting of buttock burns1 and silicone gluteal implants
that can be placed in the defect area to assist with the contouring of the deformity caused by the burn injury2. Gluteal augmentation can also be used, which uses implants and a combination of liposuction/lipo-injection procedures3. Gluteal implants are reported to have a higher success rate in comparison to liposuction and lipo-injection procedures, which require vast experience in Coleman fat injection3. Tissue expansion is another clinical procedure that can be used in the reconstruction and management of extensive burn scars, however there is a risk of complications caused when the serial expansion of the same tissues is performed repeatedly or if the expanders are located in the lower extremities4. Buttock augmentation has reported to have post surgical complications and presents great challenges with the incidence, diagnosis, management, and prevention of complications post surgery5.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
23
CASE HISTORY A 42-year-old female sustained a scald as a one-day old baby when she was in hospital. The patient presented a long scar across the right buttock and had completely lost subcutaneous fat in the area. This resulted in a significant defect with a deficit of almost half a kilo of fat.
Etchingham, East Sussex, TN19 7AL) was applied onto the stone surfaces. The waxed-up pattern was invested in a mixture of type IV dental stone material of Crystacal ‘R’ and water. Following the setting stage the mould was boiled out, separated and left to bench cool. Unifol separating medium was then applied to the mould and allowed to dry.
The patient had managed to date with the use of pieces of foam inserted under her clothing in order to maintain her contour. The patient presented superficial partial thickness burns and did not require skin grafting. She did not wish to have any surgery for placement for implants, serial excision of the scar or tissue expansion for the correction of the contour deformity.
Fig. 1: Shows two-part mould ready for packing for the external buttock prosthesis.
METHOD Following standard clinical procedure the patient was instructed to sit in an upright position and an impression of the defect area was taken using alginate impression material (Cavex Holland BV, PO BOX 852, 2003 RW Haarlem, The Netherlands) with plaster of Paris backing (John Winters & Co. Ltd., PO BOX 21, Washer Lane Works, Halifax, HX2 7DP). This was cast in Crystacal ‘R’ dental IV stone material (John Winters & Co. Ltd., PO BOX 21, Washer Lane Works, Halifax, HX2 7DP) and allowed to set. The defect area was waxed up to reproduce the natural contours of the buttock area and to fill out within the confines of her support underwear. The final waxed-up pattern was then hollowed out on the fitting surface of the wax pattern from the centre outwards leaving 2 inches around the circumference of the wax pattern.
WAX/TRY-IN STAGE
Table 1 shows the physical properties of A-588 Realistic Silicone Elastomer Materials, (Technovent, Headingley House, 39 St. Michael’s Lane, Leeds, LS6 3BR, UK, manufacturing instructions). Table 1: The physical properties of A-588 Realistic Silicone Elastomer Materials
For the wax try-in procedure the patient was shown how to insert the wax pattern into her underwear and then asked to walk in order to observe how noticeable the wax pattern was and whether it needed to be extended or shaped according to the conformity of functional movements. The patient was also assessed in gaits and seated positions, to determine the comfort of the wax pattern and whether it was noticeable. The wax pattern was adjusted and re-contoured accordingly and then re-fitted to determine the final fit.
FABRICATION OF THE HOLLOW BUTTOCK PROSTHESIS The void of the hollowed wax pattern on the cast impression model was filled with a mixture of Crystacal ‘R’ and water and allowed to set. A circular groove 20mm in diameter and 20mm deep was then ground into the middle of the cast impression model. This was done to allow compressibility of the prosthesis when the patient is in a seated position. The waxed up pattern was then sealed onto the cast model and Unifol separating medium (Bracon Limited, High Street,
24
The selected material of choice material was A-588 Realistic silicone elastomer material (Technovent Limited, Headingley House, 39 St. Michael’s Lane, Leeds, LS6 3BR, UK) as it is a translucent platinum cured silicone elastomer. Four hundred grams of this silicone elastomer material was mixed with a small amount of intrinsic colour in order to obtain a translucent buttock prosthesis and catalysed with 40 grams of A-588-3 catalyst (Technovent, Headingley House, 39 St. Michael’s Lane, Leeds, LS6 3BR, UK). This strength of the catalyst was used to ensure flexibility and firmness of the prosthesis, which was required for this type of prosthesis. The properties of the Realistic Silicone elastomer are shown in the Table 1 below.
Durometer Shore A
29
Tensile Strength (psi)
600
Tear Strength (ppi)
40
Elongation
325
Viscosity
85,000 cps
The material works well with A-300-1 Thixo Agent, (Technovent, Headingley House, 39 St. Michael’s Lane, Leeds, LS6 3BR, UK), which helps eliminate the need for vacuum deairation in a speed mixing machine and also increases the viscosity of the material to a mixture which will no longer pour, so ease of packing is achieved. The Unifol separating medium on the mould was allowed to dry and then catalysed silicone elastomer was carefully packed into the mould using a spatula to eliminate any air trapping during the packing procedure. The mould was pressure clamped and processed at room temperature for 24 hours.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
Following the curing process, the mould was unclamped, the prosthesis removed and the excess material at the edges trimmed. The prosthesis was finally cleaned with a soapy water solution.
Fig. 4: Shows the fitting surface of the finished external hollow buttock prosthesis.
The patient was initially reviewed one month post fitting and subsequently at 6 month intervals.
Fig. 2: Shows the fit of the finished external hollow buttock prosthesis on the mould.
It is important that reviews are maintained, thus patient expectations, requirements and prosthetic and clinical governance outcomes can be monitored.
FITTING OF THE EXTERNAL HOLLOW BUTTOCK PROSTHESIS
The patient did not consent to allowing any clinical photography.
During the fitting procedure the patient was asked to try the prosthesis by inserting it into her underwear and asked to walk and sit down with the prosthesis fitted as previously described. Thus, compliance of patient/prosthesis is determined.
DISCUSSION There are various surgical options available as a method of treatment, which involve serial excision of the scar or tissue expansion. However, the patient was keen to explore a more conservative approach and custom-made prosthesis was offered as a prosthetic rehabilitation option. There are two forms of prostheses available with this treatment, a complete or a hollow custom-made prosthesis. The selected choice was clear hollow silicone buttock prosthesis. The hollow aspect reduces the weight of the prosthesis, which is an important factor in the functionality and comfort of the prosthesis for the patient. This was achieved by 35% of the prosthesis being hollowed.
CONCLUSION
Fig. 3: Shows the finished external buttock prosthesis.
The finished prosthesis weighed 352 grams, thus allowing comfort for the patient and reduces the risk of drag of the prosthesis as it is light, and the hollow aspect, allowed for the compressibility of the prosthesis for when the patient was in a seating or lying position.
The advantages of custom-made external hollow buttock prosthesis over a conventional solid prosthesis are that it conformed well to the patient’s skin and was far less visible through the patient’s clothing. Being non-invasive the procedures avoid surgical and multiple surgical reconstruction and if the patient does not wish or require to use the prosthesis at anytime in the future then it can be easily discarded without any subsequent trauma. When wearing the external hollow buttock prosthesis, the patient was able to walk and sit comfortably and gained confidence, and presented a successful prosthetic outcome. New treatment materials are continually evolving. Silicone and gel silicones could be used for this kind of treatment, however further research in this area is recommended.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
25
References 1. Potaker T., Ramaswamy R., Dickson W.A. Isolated buttock burns: epidemiology and management. Burns. 2001; 27: 629–634. 2. Vergara R., Marcos M. Intramuscular gluteal implants. Aesthet Plas Surg. 1996; 20(3): 259–62. 3. Harrison D., Selvaggi G. Gluteal augmentation surgery: indications and surgical management. J Plastic Recon & Aesthet Surg. 2007; 60: 922–928. 4. LoGiudice J., Gosain A.K. Paediatric tissue expansion: Indications and complications. J Craniofac Surg. 2003; 6: 866–872. 5. Bruner T.W., Roberts T.L. 3rd, Nguyen K. Complications of buttocks augmentation: diagnosis, management and prevention. Clin Plas Surg. 2006; 3: 449–466.
The photographic pictures were taken from Sheffield Teaching Hospital NHS Trust Database.
26
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
DIGITAL PHOTOGRAPHY IN MAXILLOFACIAL PROSTHETICS N. Caulfield and C. Maryan Natalie Caulfield BSc (Hons), Dip PS, MIMPT, LOTA, Maxillofacial Prosthetist Maxillofacial Unit 1st Floor Dental Institute, Kings College Hospital Denmark Hill London SE5 9RS
Christopher Maryan BSc (Hons), LCGI, FIMPT Head of Centre and Principal Lecturer School of Biology, Chemistry & Health Science, Manchester Metropolitan University All Saints Building All Saints Manchester M15 6BH
Health care professionals need to be aware of their responsibilities in relation to patient rights, data protection and a professional manner in relation to taking and storage of photographic images, particularly digital images. Purpose: The purpose of the study was to review aspects of these regulations and how they impact upon Maxillofacial Prosthetists & Technologists (MPT). Method: A survey of MPT’s practice and a literature review was undertaken. Results: The survey identified a high level of awareness and competence by many MPT’s however a number of MPT’s were not aware of or adhering to Department of Health guidelines. Conclusions: All MPT’s should be aware of legal and professional issues of consent, the efficient use of digital photography and data storage. Every unit using this technology within their practice should produce an agreed protocol for image capture and storage. Alternatively, medical illustration only should be used as required. Keywords: Maxillofacial Technology, digital photography, purchase considerations, security, consent, Data Protection Act 1998.
INTRODUCTION
LITERATURE REVIEW
Maxillofacial Prosthetists in the modern NHS are required by clinical governance to provide clinical documentation. These include medical records, monitoring patient progress1 and medico-legal reports. They may be used to provide patient education, case presentations, teaching and treatment audits2. A review of the literature shows there to be many issues to consider when using digital photography within the practice of Maxillofacial Technology such as; costs, usability, image storage, and potential advantages over existing record systems.
Digital photography is used in many trades and professions such as Estate Agents, Advertising Agencies, Police and Media3. Its use has been investigated by Dentists4, Physicians and Otolaryngologists5. Existing literature is mostly focused on using digital photography in dental practice4, orthodontic practices2,3, or comparing different cameras and their associated advantages/disadvantages.
USAGE AND REGULATORY ISSUES Using a questionnaire this article highlights how MPT’s are using digital photography in their workplaces and highlights the relevant issues and considerations that should be taken into account with using digital photography within the practice of Maxillofacial Technology.
The associated issues when using digital photography are presented in Table 1 and this article will highlight the more important: standardisation; management; storage; consent and data protection.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
27
Table 1: Associated issues when using digital photography Number of pixels
Publishing
Light and flash
Internet and e-mail
Digital ‘v’ film
Management and storage
Projection
Standardisation
Manipulation
Data protection and consent
Printing
Security
STORAGE AND MANAGEMENT Storage refers to the medium on which your images are stored. This may be a hard drive, CD, DVD or compact media. Whereas management is how they are retrieved once saved onto the appropriate medium, e.g. a database where the patient details such as name, hospital number, date of birth, prosthesis type can be added for use later for statistical purposes.
SECURITY
STANDARDISATION Standardisation is an important factor in photography especially when the photographs are to be used for comparisons6. Using photographs for comparative purposes requires an initial point of reference. If the light, subject position and distance from the subject differ, an unbiased comparison cannot be made. The pictures in Figure 1 show the subject in good light, good position and eyes level to the Frankfort plane. The second and third show tilting, shadowing and differing ratio of the subject making a comparison difficult.
Within the NHS, protection and security of images is a priority to ensure patient confidentiality. Using your trust’s medical illustration department ensures the images are stored, backed-up and accessed appropriately. Images should never be stored on a laptop computer as there is a risk of the images being lost or stolen and used by persons outside the consent they were given.
DATA PROTECTION AND CONSENT The Data Protection Act (DPA) 19988 governs protection of personal data by companies and organisations in the UK. The act allows personnel involved in the patients care to access them but not remove them from the Trust, data should be relevant for the purpose for which it is taken and be of the minimum amount necessary.
Fig. 1: Illustrates difference in light and positioning on an image. Pictures copyright of University Hospital Birmingham.
Principles for light and flash use are largely the same in digital photography as in standard film photography. Exposure is critical for a good picture7. To capture a good picture the amount of light entering the camera must be adjusted to suit the sensitivity of the sensor7. Too much light and delicate areas of the picture are converted to white and lost, too little light and shadow areas become solid areas of black. The user must adjust the shutter speed higher to allow more or slower to allow less light through to the sensor. A digital camera contains a metering system designed to measure the amount of light entering the camera. This will be linked to an auto exposure mechanism to alter the aperture and shutter to suit the light available7. Digital cameras also have various settings for various lighting conditions i.e. indoor/outdoors, snow scene, night, fluorescent light. If these are present in the camera it will automatically adjust the light source to the setting selected. In some cameras there are light indicators (red and green) to alert the operator if there is enough light or not, so a flash unit may be added6.
28
The Caldicott report (1997)9 identified six key principles to outline justification, use, access and responsibilities with patient information for all healthcare professionals. Both of these can be found easily on the internet and within all NHS Hospitals. As healthcare professionals, it is each individuals responsibility to familiarise themselves with these documents.
METHOD Twenty maxillofacial units were contacted by telephone to evaluate their use of digital photography in their work. Additional information such as camera cost, consent, protection and security of digital images was also gathered. The participants were all picked randomly and assured anonymity.
RESULTS The questionnaire showed that 80% of MPT’s questioned already owned and used a digital camera in the management of their patients. The most common use for the photographs was for records, and a mixture of the following; construction; teaching and discussion aids; pre-post operative comparison; presentations; planning research and recording unusual or interesting prosthesis. Figure 2 illustrates these responses in detail.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
Respondents were questioned with regards to consent, if consent was sought and if it was recorded. The results are shown in Figure 5. All of the MPT’s using digital photography did seek consent and 79% always record consent. However 21% do not have consent recorded.
16 14
12 10 8
14
6 4 4
4
4
4
12
3 2
2
2
1
0
Number of respondents
Number of respondents
14
10 8 6 4 2
Fig. 2: Uses of digital photography in maxillofacial prosthetics.
0
Yes Do you seek patient consent for images?
Factors that MPT’s considered when purchasing their cameras are shown in Figure 3. The results show that 100% of respondents consider resolution important, 79% consider ease of use and 86% consider Macro features are more or very important considerations. 16 14 Number of respondents
2 12
2
2
4 2
2 10
8 10
5
7 6
6
2 2
2
1 Resolution
Ease of use
Not important
2
2
Price
Macro
Less important
More important
4
1 2
1
Recommendations
Extras
Neither
Figure 4 shows how medical photographs were stored by MPT’s. Twenty-one per cent of respondents were using a database, 43% answered software package, 7% use the PC hospital Hard Drive and 50% are using Windows application. 8 7 Number of respondents
DISCUSSION
6 5 4 3 2 1
CD
Windows program
This study outlines the various issues related to the use of digital photography that MPT’s should take into consideration. It is clear from the questionnaire that Prosthetists have a wide use for digital photography in Maxillofacial Prosthetics, from planning and research to teaching aids.
Very important
Fig. 3: Camera purchase considerations.
0
Final questions asked whether Maxillofacial Prosthetists were aware of security guidelines. This intended to determine the understanding and knowledge of the Data Protection Act (DPA) and the Caldicott report outlining the responsibility an NHS professional has for the images they are taking. Eighty-six per cent said ‘yes’, they were aware of the issues/guidelines but only 50%, when questioned further, could name either the Caldicott or DPA 1998.
8 3
0
Fig. 5: Seeking and recording patient consent.
6
8
4
No Is the consent recorded?
Software package
Hospital hard-drive
Database
Before purchasing a camera it is advisable to identify how it will be used. The camera should be considered on how it performs and it’s suitability for use, price is obviously a consideration in a purchase but should not be the defining reason to buy. Resolution and macro are important considerations with regards to the image quality. If the pictures are going to be used for a presentation, it may be that larger images are required. Therefore a picture at close range will be complimented by the detail from a high-resolution camera with good detail and colour. Ease of use is an important factor with electrical and technical goods as a more complicated camera to use may cause the operator difficulties in achieving the desired images. Operator difficulties increases the likelihood that the camera may not be used to its full potential. Fifty per cent of the responding MPT’s considered colleagues’ opinions and recommendations before purchasing. This can be useful to identify which cameras may suit the requirements for Maxillofacial Prosthetic work before committing, only to find the camera you chose may not be what was required.
Storage type
Fig. 4: Storage of images.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
29
The questionnaire highlights storage of images as an uncertain area, as to where and how the images should be stored. Respondents were asked how they stored the images, only one MPT answered on the PC hard drive, which is backed-up by the Trusts IT department. None of the other responses were related to image storage, rather what software is used to access the images. It could be that the question was either not understood by the MPT’s or the MPT questioned may not understand the term ‘storage’. However, if another study were to be taken, this question would be revised. Images should always be stored on a hospital main server, which is secure and backed-up regularly. In addition, images should never be left on laptop computers or mobile phones where they are at risk of loss or theft6. Differing opinions and understanding of how photographic records should be taken, stored and used was apparent. Patient confidentiality is essential in the NHS. The DPA 1998 and the Caldicott report outline measures for clinicians to follow ensuring that any images are lawfully taken, stored and used appropriately. Although there are guidelines for consent issued by the DOH, individual Trust’s and the Institute of Medical Illustrators, opinion on consent appears to remain fairly subjective. Advice sought from the Medical Illustration department confirmed that for photographic and video recordings, for treatment or patient assessment, must not be used for any purpose other than the patient’s care or audit of that care without the consent of the patient. Recordings for publication, research or education purposes must have consent in writing6. From the questionnaire, some MPT’s did reveal not having read these documents or knowing about them. As Health Care Professionals it is a part of our responsibility to know and understand the importance of these policies. Having no understanding of them could also mean that these MPT’s may be breaking data protection laws. Breaching rules about patient confidentiality in the NHS is very serious and treated in certain cases as professional misconduct with consequent disciplinary action by the Trust and professional bodies6. To meet with the regulations that these two reports outline, consent must be given by the patient with full understanding for the use of the images. This should be filed in the patient’s notes and may be withdrawn by the patient at any time.
CONCLUSIONS This study has highlighted, including planning the use of digital photography within maxillofacial prosthetics and investigating the specifications required of the camera. Determining the use of the images and the most appropriate method for taking, storing and archiving them. The study highlights that while many MPT’s are well informed of issues of storage and archiving, security and consent, some however are not.
30
When photographs are needed or have been taken, always be aware of consent issues and policies and ensure they are followed; find and read the latest information on consent, the DPA 1998 and the Caldicott Report from your Trust. MPT’s should always have consent for the photographs in writing before they are taken and ensure they are kept secure by agreement with the employing Trust, and in any doubt seek advice from your Medial Illustration Department. When implementing a protocol for using digital photography ensure all staff are aware of it to ensure that correct protocol for taking, storage and use of images are adhered to. All staff should sign and date the protocol once in place.
Acknowledgements I would like to express my thanks to all persons involved with answering the questionnaire. Medical Illustration at Portsmouth Hospital and University Hospital Birmingham, and Cristina Nacher, Maxillofacial Prosthetics manager, Kings College Hospital, for their help in writing this article. Photographs in Figure 1 are copyright of University Hospital Birmingham and have been consented for publication.
References 1. France I. 2003. Managing Medical Photographs – The Key Issues. 17th March. Available at: www.ibase.com/PDFdownloads/Technical/Medical.pdf accessed on 25 July 2003. 2. Hutchinson I., Ireland A.J., Stephens C.D. 1999. Dig Cam Orthodont: An Overview. Dental Update; 26: 144–149. 3. Sandler P.J., Murray A.M., Bearn D. 2002. Dig Rec Orthodont. Dental Update; 29: 18–24. 4. Dunn and Beckler, 2001. Digital photography Technology offers Unique Capabilities, Advantages and Challenges to Dental Practices. J Californ Dent Assoc. Available at: www.cda.org/member/pubs/journal/jour2001/ technology.html accessed on 23/7/03. 5. Smith R.V. 2002. The Digital Camera in Clinical Practice. Otolaryngologic Clinics of North America; 35: 1175–1189. 6. Charters S. 2003. Personal communication. Medical Photographer, Department of Medical Illustration, Queen Alexandra Hospital Portsmouth. 7. Andrews P. 2000. The Digital Photography manual. An introduction to the equipment and creative techniques of digital photography. Carlton Books Ltd, London. 8. Data Protection Act 1998. Available [online] http://www.opsi.gov.uk/acts/acts1998/ ukpga_19980029_en_1 accessed on 23/07/03 9. Caldicott F. 1997. Report on the review of Patient identifiable information. Available [online] http://www.doh.gov.uk/ipu/confiden/report/crep.html accessed on 11/10/03.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
TITANIUM CRANIOPLASTY IMPLANT CONSTRUCTION USING A SECTIONAL MOULD B.C. Edwards B.C. Edwards MIMPT Maxillofacial Prosthetist Queen Victoria Hospital Holtye Road East Grinstead West Sussex RH19 3DZ
This paper describes a method of Titanium cranioplasty implant fabrication where extensive contouring of the implant material within the forming mould is necessary. Such a deep, three dimensionally contoured implant may be required when Temporal and Sphenoid bones are bilaterally absent and present a large frontal skull defect. Keywords: Cranioplasty, Titanium, Skull Defect, Reconstruction.
INTRODUCTION
METHOD
A 23 year old male presented to the Hurstwood Park Neurological Centre, Princess Royal Hospital, Haywards Heath, West Sussex RH16 4EX following a road traffic accident with a large frontal cranial defect involving left and right Temporal and Sphenoid bones. Cranioplasty using a Titanium implant was prescribed by the neurosurgeon. Literature reviews indicated favourable infection rates using Titanium when compared to other methods of cranioplasty implant reconstruction1–3. A Computerised Tomographic (CT) scan was sent to the Maxillofacial Laboratory at East Grinstead. A Stereolithographic model (SLA) was produced from a CT scan which were dimensionally accurate, negate patient attendance for impression taking and aesthetic results following cranioplasty implant insertion were excellent4. Once the SLA model was fabricated, the procedure for the production of a Titanium cranioplasty implant was planned (Fig. 1).
First procedure of implant construction was to infill the defect area, apparent on the SLA model, using Tenatex red wax, (Bracon Ltd, High Street, Etchingham, East Sussex TN19 7AL) building this up to restore an appropriate skull contour. The recontoured skull model was duplicated and a Dentsone KD, (Bracon Ltd, see above) stone model was poured and the duplicate model was inserted into one half of a large aluminum maxillofacial flask (Fig. 2). This case presented significant undercut areas about the temporal and sphenoid regions. Such undercut areas, if poured up in the usual manner, will irremovably lock the flask halves together. Additionally, if undercut areas are surveyed and blocked out following standard procedure, mould detail will be compromised by detail lost and therefore an inaccurate implant formed. In order to avoid locking the flask halves by using standard procedure a sectional mould was designed. This incorporates removable mould components that enable the Titanium plate to be swaged into all undercut areas, and therefore counter the detail lost.
Fig. 1: Stereolithographic model.
Fig. 2: Duplicate model in one flask half.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
31
DISCUSSION A sectional design also allows trouble free separation of the (metal flask) mould; the Titanium plate may then be removed, trimmed and altered as it is formed. This method was first tried using two individual stone sections to occupy the undercuts about the Sphenoid and Temporal areas, combined with a larger stone section over the frontal bone region. However, as the Titanium plate was swaged in the mould, it was discovered that the smaller stone sections were fragile and crumbled upon removal from the mould. It was then decided to make the smaller mould sections using PMMA (Fig. 3). In the two cases this technique was attempted, the removable PMMA sections were able to withstand the forces of the swaging process. The Titanium cranioplasty implant could then be constructed in the following way.
maybe be raised and the implant inserted deep behind the muscle: less (or no) implant overlap maybe indicated due to the presence of this muscle tissue. The outline of the implant plate margin was marked upon the duplicate stone model, which was then incorporated into one half of a large aluminum flask to form the moulding implant die (Fig. 2). Locating grooves or slots were cut into areas that will be filled with the removable (PMMA) mould sections and then separator was applied. Modeling or special tray PMMA was poured into the left and right undercut areas of the die half and allowed to polymerise. The frontal region and removable PMMA sections are coated with petroleum jelly separator and were then topped with stone in the second half of the flask to form the counter-die (Fig. 4), 0.5mm commercially pure (CP) Titanium plate, (DR Beven, Llangennith, Gower, Swansea SA31HU) is then drilled with TiN coated 2mm drill-bits while still flat. 2mm holes are drilled into the Titanium plate except for the area of the implant that will form the overlap margin. Relieving slots are then cut into the Titanium plate using a cut-off disc, the slots radiating from the plate margin towards the centre of the (still flat) implant shape. Position of the relieving slots can be predicted by using a similar shaped piece of card pressed into the mould. The overlapping creases, apparent in the card pattern, will act as a guide and show where the relieving slots are required. After initial pressing, the Titanium implant was removed and edges trimmed to align with the marked implant on the model. Fixation holes are then drilled 2mm from the edge of the implant margin at 5–10mm intervals; diameter of these holes is dependent on the size of bone screws used by the neurosurgeon. Numerous (fixation screw) holes will afford the neurosurgeon multiple fixation options. The fixation screw holes are countersunk with a 13mm drill bit and checked using an appropriate Titanium fixation screw.
Fig. 3: Flask halves with PMMA sections.
When designing a Titanium cranioplasty implant, factors that must be considered are skull profile and degree of overlap between the defect and implant plate margins. A degree of overlap is required so the implant maybe firmly affixed with screws to skull bone and the defect maybe covered. Adequate implant-defect overlap also affords the Neurosurgeon options when deciding the best site for bone screw placement. However, an oversized implant will require a larger tissue flap be raised and additional soft tissue (Dura Mater) be stripped away from the boney defect margin prior to implant fixation; an unnecessary and time consuming contraindication when planning cranioplasty of large defects5. An overlap margin of 8mm is used for 0.5mm thickness Titanium cranioplasty implant plates. In the Temporal region, guidance should be sought from the neurosurgeon regarding extent of the inferior margin of the implant as the Temporalis
32
Fig. 4: PMMA sections in place.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
The outer surface of the cranioplasty implant is polished using fine pumice and Titanium polishing compound. In our experience of fitting numerous Titanium cranioplasty implants, we have found that it is easier to clean blood, tissue debris and other (drying) fluids off of the implant when the device is being fitted in the operating theatre. The implant was then marked with the patients name and the relevant medical device code using a laser under inert Argon gas. It was then placed back into the mould and pressed until a passive fit is obtained when the implant is tried against the original SLA model. When a passive fit is achieved the implant is ready for sterilisation (Figs 5 and 6).
CONCLUSION The technique described in this paper presents the Maxillofacial Prosthetist with a construction method that provides a uniform amount of force to the implant and accuracy with regard to the fit of the implant device. The implant device is also fabricated and supplied as a simple one-part device.
Acknowledgements Sincere thanks to M. C. Cutler for help in the compilation of this article and Katie Salisbury of the photographic department for providing the images.
References 1. Blake G.B., MacFarlane M.R., Hinton J.W. Titanium in reconstructive surgery of the skull and face. Br J Plas Surg. 1990: 43: 528–35. 2. Eufinger H., Wehmoller M., Harders A., Heuser L. Prefabricated prostheses for the reconstruction of skull defects. Int J Oral Maxillofac Surg. 1995: 24: 104–10. 3. Joffe J.M., Aghabeigi B., Davies E.H., Harris M. A retrospective study of 66 titanium cranioplasty. Br J Oral Maxillofac Surg. 1993: 31: 144–8. 4. Joffe J.M., Nicholl S.R., Richards R., Linney A.D., Harris M. Validation of computer assisted manufacture of titanium plates for cranioplasty. Int J Oral Maxillofac Surg. 1999: 28: 309–313. 5. Koppel D.A., Moos K.F., Walker F.S., Skull reconstruction with a two part interlocking custom made interlocking plate. Br J Oral Maxillofac Surg. 1999: 37: 70–72.
Figs. 5 and 6: Finished implant on SLA model showing left and right aspect.
Titanium cranioplasty implants, with deep three dimensional curves, may be formed, in the usual manner, using upper and lower flask halves and moulds. However, on removal from the mould an implant will require extensive modification, using hand tools, to recover contour accuracy and achieve a passive fit. Larger cranioplasty implants, with deep three dimensional curves, maybe fabricated in sections and then fitted together in situ upon the patient in the operating theatre. Sectional design implants may also be fabricated in separate moulds and co-joined by laser welding in the laboratory prior to fitting.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
33
The Journal of Maxillofacial Prosthetics & Technology
TS IS
TE ITU ST IN
ISTS & TECHN OL HET ST OG RO
OF MAXILLO FAC IA L
P
TH E
ABSTRACTS 23RD IMPT SCIENTIFIC CONGRESS 2007 PRESENTATIONS
the difficulties in practically linking the technologies are described.
What do you need? Who can help you? Assessing the quality of life in individual patients in routine clinical practice Fisher S Maxillofacial Surgery, Faculty of Medicine and Health, University of Leeds Our patients suffer not only the consequences of their disease or disorder and its diagnosis be that developmental, trauma or cancer related but the ongoing effects on important functions, such as speech and swallowing, challenges in terms of appearance and resulting problems in resuming an active social life or a return to employment. It is these ‘impacts of disease’ areas which were highlighted in a recent major study by Macmillan Cancer Support (the ‘Listening’ study) as the most important area for patients and carers.
CAD/CAM Technology in constructing maxillofacial prostheses; Review of the literature Hatamleu M Applications of the CAD/CAM system in maxillofacial prosthodontics include the fabrication of different facial prostheses of defect sites. Generally, the automated fabrication of facial prosthesis follows the steps of taking facial impression of the defect side using a laser scanner to provide a 3D facial measurement. Then the data is sent to a computer to generate a cast of the patient’s defective side for fabricating a physical prototype of the prosthesis using either rapid prototyping or Computer Numerically Controlled milling (CNC).
My background is as an active maxillofacial oncology surgeon in the period when free tissue transfer was becoming the norm. In time, the decisions about what we should do (or not) and how people coped with their disease became a major focus of my work and I moved to an academic appointment here in Leeds in 2000 to facilitate progress of head and neck related research.
This work reviews the different CAD/CAM techniques used and the recent advances present till this date.
This lecture will focus on my work to investigate the needs of individuals and to look at the way their needs might be identified and met. We have used both touch-screen computer technology and interviews and are currently evolving a communication tool for use by all health professionals and their patients, for information, setting goals for progress together and for monitoring needs, areas of difficulty and of progress.
There has been much discussion on the application of digital technologies in extra-oral, facial prosthesis production, particularly in the last ten years. Much of the literature has relied upon the evaluation of a single case study or has concentrated on the engineering or the clinical aspects of the process. Thus coherent conclusions on how digital technologies may be effectively integrated into health care systems have not yet been made.
Computer-Aided Design of orbital rim implant Pilley M Leicester Royal Infirmary The use of Computer Aided Design (CAD), Rapid Prototyping and Computer Aided Manufacture (CAM) can optimize facial reconstruction. This case shows a patient who underwent extended maxillectomy for ameloblastoma and had several reconstructive operations but was left with an orbital rim and malar prominence deficit. CAD was used to replicate the normal anatomical form of this site, mirrored from the opposite side, and a CAM wax pattern used to produce a cast titanium implant. The steps in this process and
34
Conclusions on digital technologies in soft tissues facial prosthesis designs Eggbeer D PDR, Cardiff
What was research is now becoming regular clinical practice in some major units. Critical evaluation of quality, clinical effectiveness and economics is vital to ensure that the development and integration of digital technologies meet the demands of the maxillofacial prosthetics profession, patients and the health care system. This presentation will conclude the findings of a program of doctoral research into the application of digital, computeraided technologies to facial prosthesis production. Critical evaluations of currently available technologies and techniques will be discussed and conclusions on how they may be best applied to meet the needs of Prosthetists, patients and the health care system given.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
The Face – a mirror of the soul Schwipper V Therapy of large basal cell carcinomas and the so-called terebrans basal cell carcinoma often requires tumour resections which are mutilating, such as amputation of the nose, orbital exenteration, resection of large areas of facial skin, and/or amputation of midfacial bones. Frequently the patients have refused any therapy for many years and have been living in social isolation. One hundred and eight large skin tumours involving the midface were operated at Fachklinik Hornheide in a five-year period. Individual psychological and psychosocial care was necessary for each of these patients prior to surgery and individual surgical treatment plans had to be worked out. Following surgical resection of the tumour, one step for rehabilitation of the individual patient consisted in surgical repair of the midfacial defects by local and distant flaps as well as transfer of microsurgically anastomozed free flaps. The other important step was preparing individual implantborne facial prostheses using magnetic or implant-bar fixation. This type of fixation of modern craniofacial prostheses largely contributes to a patient’s private, social and professional rehabilitation. Especially cases of orbital exenteration and those with a lack of surgical means to reconstruct the eyelids nicely demonstrate the possibilities of modern facial prostheses.
individual amount of local alveolar bone. Therefore, further research validating LDFs use in human beings; especially in those who have undergone radiation therapy for head and neck cancer is necessary.
Maxillofacial Unit-Dhaka – Bangladesh Gill L, Page K University of Sheffield, Frenchay Hospital Bristol In November 2005 we introduced the first training programme in Maxillofacial Prosthetics at Dhaka Community Hospital. The Hospital was established in 1988 and is a Trust-owned, non-profit-making organisation providing health care for low income underprivileged people. The nutritional status and health care awareness of the people is poor, particularly in the rural areas, the women, children and elderly are often a substantial distance away from any medical facility and as a consequence of this, it’s this group that suffer the most. With this in mind we are returning to Dhaka in November with a larger team and aim to cover seven specialist areas from breast work to obturators. Our long term objectives are to return every year with a different team of specialists and we have recently formed our own website and are in the process of forming a charity called MPT’s Abroad. This website will be available shortly (mpt’sabroad.com) and will contain lecture presentations, information/advice of working abroad and contact details should you wish to join the team.
Assessment of vascularity in irradiated and non irradiated alveolar bone by laser Doppler Flowmetry, an animal study
I would like to work overseas in a developing country
Verdonk H
Following my early retirement from the NHS as a Consultant Maxillofacial Prosthetist, it was my intention to work as an overseas consultant in developing countries ‘the purpose of this short presentation is to identify some of the pitfalls that may arise with working overseas in developing countries and the rewards should you be successful’.
The purpose of this animal study was to confirm that Laser Doppler Flowmetry (LDF) is a reproducible method for assessing maxillary and mandibular alveolar bone vascularity and that maxillary and mandibular alveolar bone vascularity is less in irradiated bone when compared to non-irradiated bone. All maxillary and mandibular premolars and molars of 6 Gottingen minipigs were extracted. After a 3-month healing period, 3 minipigs received irradiation at a total dose of 24 Gy. At 3 months after irradiation, 5 holes were drilled in the residual alveolar ridge of each edentulous site of all minipigs. Local micro vascular blood flow around all 120 holes was recorded by LDF, prior to implant placement. In 1 irradiated and 1 non-irradiated minipig, an additional hole was drilled in the right edentulous maxillary site in order to be able to perform repeated LDF recordings. The alveolar bone appeared less vascularised in irradiated than in nonirradiated minipigs. The effect of radiation showed to be more pronounced in the mandible than in the maxilla. LDF was demonstrated to be a reproducible method for assessing alveolar bone vascularity. However, recordings varied per edentulous site as well as per minipig. In order to be useful in human beings, normal values of vascularity of the various alveolar sites should be known. These values may not only vary from person to person, but may also be depending on the
Haylock C
Maxillofacial Prosthetist – a requirement Chowdrey R In recent years there has been much advancement in many other disciplines in dentistry. There has been a progressive worldwide demand for the specialised services personals. Maxillofacial Prosthetist is one of them. But unfortunately in many countries there is a severe shortage of suitable trained, qualified persons capable of providing this service for the patients who require them. This paper will highlight the present status of maxillofacial prosthesis specialty in my country, the advancement in material science, social stigma the patients suffer from, the amount of importance pertaining to maxillofacial prosthesis specialty given in dental education curriculum, and then finally an appeal to the congress for suggestions and involvement for the betterment of the patients of my country.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
35
A comprehensive diploma programme in maxillofacial prosthetics in the Indian sub-continent – need of the hour Kheur M India has the dubious distinction of having the largest number of oro-facial cancer patients in the world. Oral cancer accounts for approximately 25 per cent of all cancer cases in the subcontinent, as per latest studies. Lack of awareness in the population, the socio-economic status of the affected and a compromised healthcare-delivery system (especially in the rural areas) usually result in patients undertaking treatment in advanced stages of the disease and thus require extensive surgeries, followed by chemotherapy and/or radiotherapy. Thus the role of a maxillofacial Prosthetist is critical in completing the overall rehabilitation of the patient. Presently, maxillofacial prosthetic technology is taught as part of the post-graduate curriculum in Prosthetic Dentistry. There is a greater emphasis on Intra-oral prosthetics only. The lack of materials (especially silicones and other elastomers), lack of training in using the same, lack of expertise and experience is a big hurdle towards fabricating extra-oral prostheses. The same is not covered in any academic curriculum in the country, including that of Dental Technology and hence laboratory support is also lacking for those few who wish to practice. A lack of remuneration coupled with the reasons mentioned above, does not make a full-time, dedicated Prosthetist profession very viable, at this time. There is an acute need to train the trainers in the subcontinent towards Maxillofacial Prosthetics. The curriculum at institutes that run courses, such as Kings College, Chicago Dental School and Mahidol University can be used as a scaffold towards developing a program for the sub-continent. This paper discusses the need and also presents an outline for such a program. The program would be tailor made to suit the requirements of the concerned personnel in the prevalent conditions and is aimed at advancing the noble science of Maxillofacial Prosthetics via training of clinicians and dental technicians, to enable them to treat and serve the patients.
Case study: Laboratory and surgical Approach to complex Maxillary Hypoplasia – an unorthodox way forward Paul P Southern General Glasgow
The partial orbital prostheses Brom J Heidelberg, Germany Two cases of partial orbital defects are present. Both are provided by a partial prostheses. The difficulties and the problems of those prostheses are shown.
The use of silicone foam in prosthetic restoration of post surgical necrotizing faciitis Payne G Southern General Glasgow Case study of a 62-year-old lady with postsurgical Necrotizing Fasciitis. A large excision of tissue was taken from right side of the chest wall and abdomen extending on to her back and anteriorly to the midline. The right breast was also removed. I will describe the fabrication of an extensive body prosthesis using Matrix M-3240 Silicone foam and the success of retaining the prosthesis with a made-to-measure garment.
20 Years of craniofacial rehabilitation in South Wales Evans P Morriston Hospital, Swansea In 1987 the South Wales Facial and Audiological Implant Team (SWFAIT) treated their first prosthetic case. Over 200 patients later we present the successes and lessons learnt over the past 20 years in relation to planning, surgery, nursing and prosthetics. Finally the presentation looks at the future for Craniofacial Prosthetic rehabilitation in the UK.
Locator Locator Locator Silk H Poole Hospital NHS Trust Case presentation of patient with nasal collumella prosthesis and the use of a locator abutment for retention.
In-house custom-made TMJ implants Bowman P Ninewells Hospital, Dundee
A 48-year-old female was referred to our Maxillofacial Department after an unsuccessful Le Fort I osteotomy to correct Maxillary Hypoplasia. The bone graft had become infected and she suffered Osteomyleitis and Sepsis for 3 years postoperatively. Distraction Osteogenisis was attempted to correct the deformity, however due to poor bone quality was unsuccessful.
36
Reconstruction is to be attempted using an Osteocutaneous Flap. I will present the complex laboratory surgery planning, and construction of templates for the correction of this patient’s deformity.
There are custom made TMJ already available on the market. However, this lecture describes a developed method of inhouse production of a two part TMJ joint implant built upon stereolithographic models, along with custom location templates. The results are promising, providing a reduction in implant cost and theatre time.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
Becoming a member Kearns A Queen Victoria Hospital, East Grinstead
OTHER PRESENTERS WITH NO ABSTRACTS
Opinions on the Maxillofacial diploma, two years Vocational Training and the AIB process are given through confidential questionnaires.
Sliney D Geographical variables of sunlight resulting in higher incidence rates of age-related disease of the skin and eye. “Keynote speaker – BAOMS Sponsored lecture”
Perspectives given on the new structure to become a full IMPT member through the people who have completed this epic journey.
From Bond to Bones: Evolution of a novel composite for Craniomaxillofacial reconstruction
Positive and negative views are expressed; advice is given on how to improve – not only lecturers and institutes, but line managers and senior colleagues.
Professor Rudd C Dean, Faculty of Engineering, University of Nottingham
‘Does my bung look big in this’
Evolving concepts in chemo radiotherapy for Head and Neck Cancer
Jenner R Kent and Canterbury Hospital
Dr Coyle C Clinical Oncologist, Leeds Teaching Hospitals NHS Trust.
This study compares the weight of packing materials used for immediate surgical Obturation. This study also offers an evaluation of material retention methods and a calculation of cost.
Evolving aspects of of Oncology Surgery
Pressure therapy and its effectiveness in the Treatment of keloid scars
Working in the real world (registration, ethics and litigation)
Dimond J Queen Elizabeth Hospital, Birmingham
Maryan C Manchester Metropolitan University
The aim of this study is to evaluate the effectiveness of pressure therapy in the treatment of keloid scarring of the pinna. The study was conducted at the department of maxillofacial prosthetics at the Queen Elizabeth Hospital, Birmingham. 25 patients participated in the study over an 18-month period. The results show that pressure therapy is an effective treatment of keloidal scarring. However, patient compliance is a major factor in achieving good results. A new pressure splint design was developed and trialed during the study, which received positive feedback from patients.
P G Tips an over view of the authors preferred techniques Garraway P Royal West Sussex Trust, St Richards Hospital, Chichester An over view of the authors preferred techniques for fabricating prosthetic nails, Ocular shell prostheses and an anti-TMJ dislocation appliance.
Mr Ong T K Maxillofacial Surgeon, Leeds Teaching Hospitals NHS Trust
POSTER DISPLAYS Review of lagopthalmos treatment Orbanja C Poole Hospital NHS Trust Review of different weight systems to correct paralysis of the orbiculari oculi muscle.
Studies on masticatory efficiency in patients after resections in maxillary region Reitmeier B, Brom J Dresden The results of this study show that masticatory efficiency of the patients with resection prostheses was the lowest. Based on the aforementioned results and the data from the nutrition reports, an attempt was made to develop nutritional guideline for the patient with resection prostheses.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
37
Investigations of water sorption and UV absorbance to penetration depth of five clear heat-cured PMMA resins
The evolution of an intraoral trifocal mandibular transport disc distractor-concept to clinical application
Gill L University of Sheffield
Walker F, Beale V R, Ayoub A Southern General Glasgow
This work focuses on a comparison of five clear PMMA resins commonly used in the production of artificial eye prosthesis.
Introduction
Maxillofacial Prosthetics in Japan Katsumata M Morriston Hospital, Swansea
A prototype intra-oral distraction device has been developed which can be used for trifocal distraction to reconstruct mandibular segmental defects. The development of this devise will be discussed and the application of the distractor demonstrated using a clinical case. Methods
Japan has a population of 125 million, we describe the facial and body prosthetic provision to this large populace, with discussion on how the service is funded and geographical distribution of clinics. Implant systems used along with materials are described and results illustrated.
Pull-out behaviour of glass fibres embedded into Biomedical Silicone in fibre reinforced maxillofacial prostheses Hatamleh M Turner Dental School, Manchester Fibre-reinforced maxillofacial prostheses have been presented recently in treating patients with facial disfigurements. Such prostheses include the fabrication of a framework of glass fibres and injecting the silicone through the framework.
The prototype distractor was custom-made in the maxillofacial laboratory. The device consists of a squaretapped threaded rod preshaped to match the desired dimensions of the new bone and tissues. It is attached to the posterior mandible on each side by 2 fixation plates which provide anchorage and stability. Anterior plates are attached to the rod via a square sleeve and fixed to the osteotomised bone transport segments. These are distracted after a 5 day latency period by turning a nut behind the sleeve which transports the bone segments forward 0.5mm with each complete turn following the vector determined by the position and curvature of the rod until they meet. The development of the devise and it’s use to recreate bone and soft tissues in a longstanding anterior mandibular defect resulting from a childhood malignancy will be demonstrated. Results
This study aimed to test the effect of embedding length of glass fibres into heat vulcanised silicone through conducting pull-out mechanical test.
Approximately 6cm of anterior mandibular bone was formed via trifocal transport disc distraction osteogenesis using this device.
The use and need of patient information leaflets
Conclusions
Moore Y Southern General Glasgow A patients understanding of their treatment and care/wear of their prosthesis is needed to prolong the life span of their prosthesis which in turn will help the patient maintain confidence in their treatment helping to improve their psychological well being.
Transport disc distraction is a realistic option for reconstruction of segmental mandibular defects in selected cases. This original design for a prototype distractor which allows recreation of the anterior mandibular contour is contained entirely intra orally. Further modifications to the prototype device are underway.
Hair control in Maxillofacial Surgery and Prosthetics: back to the roots
The aim of the research was to review the professional, legal, ethical and design issues relating to patient information leaflets and their effectiveness.
Carter L.M1, Bartlett P2, Parsonage-Grant S3, Patterson A.R1, Wales C.J4, Chan W5 Aberford Road, Wakefield, West Yorkshire WF1 4DG.
This research will be used to determine a protocol for the writing of leaflets.
1 2 3
For the maxillofacial prosthetics and technical service of the Glasgow Southern General.
4 5
38
Specialist Registrar Maxillofacial Prosthetist Senior House Officer, Oral and Maxillofacial Surgery, Leeds Dental Institute, Leeds LS2 9LU Specialist Registrar, Oral and Maxillofacial Surgery, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB9 2ZB Senior House Officer, Plastic Surgery, Pinderfields General Hospital
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
Many procedures in Maxillofacial Surgery and Prosthetics involve the hair bearing scalp or the hair bearing skin of the face. Effective hair control prevents hair from entering the surgical wound or area for impression, thus limiting interruptions from irritating hairs obstructing the operative field, and allowing optimum wound closure by enabling good visualisation of wound edges. Shaving the scalp or facial hair has been practised for over one hundred years. This produces a clear operating field but can be associated with a higher risk of wound infection and can cause psychological trauma and delays in rehabilitation by affecting the patient’s body image. Various alternative hair control techniques that obviate the need for shaving have been described. The aim of this study was to illustrate and discuss the various techniques for scalp and facial hair control practised in Maxillofacial Surgery and Prosthetics. Therefore a literature review of published methods of scalp and facial hair control was performed. Numerous hair control techniques were identified which can be classified into depilatory, parting, bundling/banding, and draping techniques. Examples of the various techniques include shaving, clipping, depilatory cream, gelling, braiding, banding/clasping with rubber bands/haemorrhoid ligatures/urinary catheters/metal foil/cable ties/rollers, and covering the hair with a swimming cap. Moustache hair can be controlled in nasal procedures with the use of adhesive drapes/dressings. Careful management of scalp and facial hair in Maxillofacial Surgery and Prosthetics can allow a more efficient procedure, producing accurate and cosmetically pleasing results with no increased risk of infection. The various methods are illustrated and discussed.
A novel modification in construction of titanium cranioplasty for large craniofacial defects Carter L.M1, Bartlett P2, Russell J.L3 Oral and Maxillofacial Surgery, Leeds Dental Institute, Clarendon Way, Leeds LS2 9LU 1 2 3
Specialist Registrar Maxillofacial Prosthetist Consultant
Craniofacial bone loss due to traumatic injury, infective process or surgical resection of malignant disease is a significant clinical problem. Reconstruction with cranioplasty must not only be aesthetically pleasing, but must have adequate strength and dimensional stability to protect intracranial structures, and allow follow up with current imaging techniques.
difficult to fix to surrounding bone. Resorbable osteoinductive scaffolds herald much promise for the future but are not yet ready for routine clinical use, especially in large defects. Titanium is therefore the current material of choice for reconstruction of large craniofacial defects. Our method for construction of titanium cranioplasty is indirect and is based on producing a model from the craniectomy bone flap or from a stereolithographic model of the cranial vault defect using computed tomographic data. A card template is then fashioned using this model, from which the cranioplasty cuts can be planned. The pre-cut titanium is then swaged using a press and ball-peine hammer. As the plate is pressed into place, further cuts may be necessary. Perforations are then prepared which allow expansion and drainage of cerebrospinal fluid and also allow fixation to surrounding bone using titanium bone screws. Any sharp edges are smoothed and rounded off using a rubber wheel. The whole surface is pumiced and then bead blasted before passivation and anodising. This is widely believed to increase the biocompatibility of the implant. This method for construction of titanium cranioplasty for reconstruction of large craniofacial defects has proved simple and inexpensive and is illustrated and discussed in this poster.
Prosthetic nasal reconstruction with Zygomatic Implants using drill guides from computer generated models and direct production from computer data Hodder S, Evans P, Bocca A Morriston Hospital, Swansea This poster will highlight the use of digital computer technology for the replacement of zygomatic implants for prosthetic nasal retention. The development of drill guides has: 1) Allowed avoidance of critical structures with minimal exposure of the facial skeleton. 2) Greatly reduced the operating time. 3) Gives a more favorable and predictable postoperative position of the implants and emergency profile of the implant for placement of magnets or bars and clips for retention of the prosthesis. 4) Allowed a more biological nasal air flow. 5) Increased patient satisfaction. 6) Utilisation of CT data for construction of wax Rapid Prototype prosthesis, dramatically reducing prosthetic construction time. Seventeen cases have been treated to date with a loss of only two zygomatic implants in irradiated patients with recurrent malignant diseased SCC’s of nose.
In large defects, harvest of autogenous bone is limited and can produce unacceptable donor site morbidity. Titanium is strong, light, has similar thermal expansion to bone, is radiolucent and can be fixed to surrounding bone easily. Methyl methacrylate is thicker yet mechanically inferior to titanium and is also
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
39
TS IS
TE ITU ST IN
ISTS & TECHN OL HET ST OG RO
OF MAXILLO FAC IA L
P
The Journal of MAXILLOFACIAL PROSTHETICS & TECHNOLOGY
TH E
The Official Journal of The Institute of Maxillofacial Prosthetists & Technologists
This Journal is published annually and reaches a wide International audience which includes some of the most influential leaders in the field. It is an important contributor to the development of this specialty. The Journal covers all aspects of Maxillofacial Prosthetics and Technology including: n n n n n
n
Implantology
n
Ocular Prosthetics
n
Intra Oral Prosthetics
n
Neurosurgical Appliances
n
Burns Pressure Therapy Appliances
Splint Therapy Psychological Issues Orthognathic Planning Facial and Body Prosthetics 3D Technologies
Free to IMPT Members
"
To order your copy, please complete the form below and return to: Type Script, 7 Carmelite Way, Hartley, Kent DA3 8BP, UK. Telephone: +44 (0)1474 707896 E-mail: design@typescript.plus.com
Subscription form Name: Address:
Postcode: Telephone:
Fax:
Please send me copy/copies of the Journal of Maxillofacial Prosthetics & Technologists at £40.00 per copy (+ £5.00 per copy post and packaging for all international orders). I enclose a cheque for £ (Please make cheques payable to ‘The Institute of Maxillofacial Prosthetists and Technologists’, in Sterling only).
40
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
TS IS
TE OF MAXILLOFA ITU CI ST AL IN
ISTS & TECHN OL HET ST OG RO
The Journal of Maxillofacial Prosthetics & Technology
P
TH E
INSTRUCTIONS TO AUTHORS
Original articles, editorial correspondence and suggestions for review articles should be sent to Dr. M Anwar Bamber, Department of Oral and Maxillofacial Surgery, UCL Eastman Dental Institute, University College London, University of London, London WCIX 8LD, UK. Authors are requested to submit three hard copies of their typescript and illustrations. Each paper must also be submitted on a computer disc or CD. Authors must keep one copy for their reference. The editor cannot accept responsibility for damage or loss of typescripts or discs. A paper is accepted for publication on the understanding that it has not been published or submitted simultaneously to another journal in the English language. Rejected papers will be returned to the authors. Typescripts that contain the results of human and/or animal studies will only be considered for publication if it is made clear that a high standard of ethics was applied in carrying out the investigations and an appropriate ethical approval was obtained. The editor reserves the right to make editorial and literary corrections. Any opinions expressed or policies advocated do not necessarily reflect the opinions or policies of the editor.
Copyright In order for us to ensure maximum dissemination and copyright protection of material published in the journal, copyright must be explicitly transferred from the author to the Institute of Maxillofacial Prosthetists and Technologists. The copyright transfer agreement will be sent to you by the publisher with your proofs. A copy of the agreement must be signed by the principal author before any paper can be published. We assure you that no limitation will be put on your personal freedom to use material contained in the paper without requesting permission, provided acknowledgement is made to this journal as the original source of publication.
Presentation of Typescripts These instructions are in accordance with the International Committee of Medical Journal Editors. Uniform requirements for manuscripts submitted to biomedical journals. Br Med J 1988; 296: 401–405 Papers should be submitted in journal style. Failure to do so may lead to significant delays in publication. Papers should be typed in double spacing throughout on good, white A4 paper with a margin of at least, 3cm all round. Type only on one side of the paper. Three copies of the typescript and illustrations should be submitted and authors should retain a copy for reference.
Full Papers Papers should be set out as follows, with each section beginning on a separate sheet: title page, summary, text, acknowledgements, references, tables, captions to illustrations. Title page – the title page should give the following information: 1) title of the article, 2) initials, name (with designatory letters) and address of each author and positions held, 3) name, address, telephone number, fax number and e-mail of the author responsible for correspondence and to whom requests for offprints should be sent and 4) sources of support in the form of grants. Summary – this should consist of not more than 150 words summarising the contents of the article. Also a small number of keywords should be included to accurately identify the subject of your paper. Text – headings should be appropriate to the nature of the paper and it should be noted that the use of headings enhances readability. Normally only two categories of headings should be used: major ones should be typed in capital letters in the centre of the page; minor ones should be typed in lower case (with an initial capital letter) at the left hand margin. References – the accuracy of references is the responsibility of the author. References should be entered consecutively by Arabic numerals as a superior in the text. The reference list should be listed in numerical order on a separate sheet in double or triple spacing. References to journals should include the author’s name and initials (list all authors when
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10
41
six or fewer; when seven or more, list only the first three and add “et al”), full title of paper, journal title abbreviated using Index Medicus abbreviations, year publication, volume number, first and last page numbers (i.e. Vancouver style).
Patient confidentiality – where illustrations must include recognisable individuals, living or dead and of whatever age, great care must be taken to ensure that consent for publication has been given.
For example: Shaw S.M., Williams E.P., Allsop E.W. Laboratory testing of new prosthetic materials. Am J Med 1994; 692: 231–240.
If identifiable features are not essential to the illustration, please indicate where the illustration can be cropped.
References to books should be set out as follows: Glennon A.W. The Science of Maxillofacial Prosthetics. 2nd ed. Philadelphia: Saunders W.B. 1995. Tables – these should be double spaced on separate sheets and contain only horizontal rules. Do not submit tables as photographs. A short descriptive title should appear above each table and any footnotes, suitably identified, below. Care must be taken to ensure that all units are included. Ensure that each table is cited in the text. Illustrations – A maximum of 8 illustrations including photographs should be included with any one paper. Additional illustrations can be included at discretion of the editor. Line illustrations – should present a crisp black image on an even white background (127 x 173mm (5 x 7in)). Photographic illustrations and radiographs – should be submitted as clear, lightly contrasted black and white prints (unmounted), sizes as above (or colour slides where appropriate, for example, where facial or body prosthetics are being shown). Photomicrographs should have magnification and details of staining techniques shown. Radiographs should be submitted as photographic prints, carefully made to bring out the detail to be illustrated, with an overlay indicating the area of importance. Photographs and illustrations submitted on disk should be saved in tif format scanned at a minimum resolution of 300 x 300 dpi. Figures should be submitted appropriately lettered in capitals. The size of the letters should be appropriate to that of the illustration, taking into account the necessary size reduction. All illustrations should be clearly marked (by label pasted on the back or by a soft crayon) with figure number and author’s name and the top of the figure should be indicated by an arrow. Never use ink of any kind. Do not use paper clips as these can scratch or mark illustrations. Captions should be typed, double spaced, on separate sheets from the typescript.
42
In cases where consent has not been obtained and recognisable features may appear, it will be necessary to retouch the illustration to mask the eyes or otherwise render the individual “officially unrecognisable”. Permission to reproduce borrowed illustrations or table or identifiable clinical photographs – written permission to reproduce borrowed material (illustrations and tables must be obtained from the original publishers and/authors and submitted with the typescript. Borrowed material should be acknowledged in the captions in this, style: “Reproduced by the kind permission of (publishers) from ... (reference)”. If authors would like acknowledgement of where the paper was initially presented, please include the details with the text, immediately following the summary.
Page Proofs Page proofs are sent to the author for checking. The proofs, with any minor corrections must be returned by fax or post to the Editor within 48 hours of receipt.
Proprietary Names Proprietary names of materials, instruments, etc. should be indicated by the use of initial capital letters. Initial capital letter, followed by the full address in brackets in the text.
Abbreviations and Units Avoid abbreviations in the title and abstract. All unusual abbreviations should be fully explained at their first occurrence in the text. All measurements should be expressed in SI units. Imperial units are acceptable from USA contributors. For more detailed recommendations, authors may like to consult the Royal Society of Medicine publication entitled Units, Symbols and Abbreviations: A Guide for Biological and Medical Editors and Authors.
PDF proof A PDF file of individual articles can be requested from Type Script as no offprints are produced.
The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10