International Dentistry Australasian Edition - Vol. 10 No. 4

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VOL. 1 0 NO. 4 IN THIS ISSUE

William H Liebenberg Intracoronal bleaching of pulpless discolored lower incisors Johan Hartshorne Does bruxism contribute to dental implant failure?

Leendert Boksman, Gary Glassman Rationale for the suggested use of fibre post segments in composite core buildups for endodontically treated teeth Edward A. McLaren, Lee Culp Smile analysis and photoshop smile design technique Nika Vafaei, Carlo Ferretti Achieving predictable outcomes of mandibular reconstruction with virtual treatment planning Crispian Scully Making sense of mouth ulceration: part nine

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Contents Volume 10 No. 4

22

4

Clinical Intracoronal bleaching of pulpless discolored lower incisors William H Liebenberg

16

Clinical Does bruxism contribute to dental implant failure?

Johan Hartshorne

22 Case Report

Rationale for the suggested use of fibre post segments in composite

34

core build-ups for endodontically treated teeth Leendert Boksman, Gary Glassman

34 Clinical

Smile analysis and photoshop smile design technique Edward A. McLaren, Lee Culp

50 Clinical

Achieving predictable outcomes of mandibular reconstruction with virtual treatment planning

50

Nika Vafaei, Carlo Ferretti

58 Clinical

Making sense of mouth ulceration: part nine Crispian Scully

62 Products

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Helping hand for Adelaide’s most vulnerable

Vol. 10 No. 4 ISSN 2071-7962 PUBLISHING EDITOR Ursula Jenkins

Common Ground Community Outreach Dental Program brings dental care to Adelaide’s homeless population. They have been doing this since 2011 and the clinic has seen over 750 patients with numerous repeat visits. Teaming with Adelaide University, the clinic also provides training for students which is an ideal situation to provide much needed care while providing quality supervised treatment.

While they run the clinic in the most cost effective way they can, there is of course a need for funds to continue the good work they do. The University of Adelaide together with Henry Schein Halas through the Henry Schein Cares program teamed together to organise a charity event with all proceeds going towards the clinic.

On the 16th October 2015 at St Marks College in North Adelaide, guests were treated to a three course meal while being entertained by all dental band - Fang Coup. The event hosted several opportunities for guests to donate to the clinic, including a live auction, silent auction and the very popular mystery wine wall.

“We are so pleased to be able to help the University and the clinic in this fun way. Common Ground Community Outreach Dental Program is the perfect fit for our Henry Schein Cares Program as it incorporates our goal of ‘doing well by doing good’ - as well as helping in the oral health domain” said Gordon Anderson, Vice President, ANZ Henry Schein.

The $44 000 raised on the night will ensure the clinic continues to run in 2016.

While the event was a huge success, more funds are needed. If you would like to donate or are interested in volunteering in the clinic, please contact Margie.steffens@adelaide.edu.au.

EDITOR-IN-CHIEF Prof Dr Marco Ferrari

ASSOCIATE EDITORS Prof Cecilia Goracci Prof Simone Grandini Prof Andre van Zyl

EDITORIAL REVIEW BOARD Prof Paul V Abbott Prof Antonio Apicella Prof Piero Balleri Dr Marius Bredell Prof Kurt-W Bütow Prof Ji-hua Chen Prof Ricardo Marins de Carvalho Prof Carel L Davidson Prof Massimo De Sanctis Dr Carlo Ercoli Prof Livio Gallottini Prof Roberto Giorgetti Dr Patrick J Henry Prof Dr Reinhard Hickel Dr Sascha A Jovanovic Prof Ivo Krejci Dr Gerard Kugel Prof Edward Lynch Prof Ian Meyers Prof Maria Fidela de Lima Navarro Prof Hien Ngo Prof Antonella Polimeni Prof Eric Reynolds Prof Jean-Francois Roulet Prof N Dorin Ruse Prof Andre P Saadoun Prof Errol Stein Prof Lawrence Stephen Prof Zrinka Tarle Prof Franklin R Tay Prof Manuel Toledano Dr Bernard Touati Prof Laurence Walsh Prof Fernando Zarone Dr Daniel Ziskind PRINTED BY KHL PRINTING, Singapore International Dentistry - Australasian Edition is published by Modern Dentistry Media CC, PO BOX 76021 WENDYWOOD 2144 SOUTH AFRICA Tel: +27 11 702-3195 Fax: +27 (0)86-568-1116 E-mail: dentsa@iafrica.com www.moderndentistrymedia.com

© COPYRIGHT All rights reserved.

No editorial matter published in International Dentistry Australasian Edition may be reproduced in any form or language without the written permission of the publishers. While every effort is made to ensure accurate reproduction, the authors, publishers and their employees or agents shall not be held responsible or in any way liable for errors, omissions or inaccuracies in the publication whether arising from negligence or otherwise or for any consequence arising therefrom.

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CLINICAL

Intracoronal bleaching of pulpless discolored lower incisors William H Liebenberg

Abstract Intracoronal bleaching of pulpless discolored lower incisors is a valuable treatment modality currently disregarded by many clinicians because of the potentially disastrous consequence of cervical resorption. A patient-administered, intracoronal carbamide peroxide bleaching technique is described. This modified walking bleaching method minimizes the risks, because treatment time is reduced to days as opposed to weeks of the original walking bleaching protocol, the concentration of the hydrogen peroxide is markedly reduced, and residual hydrogen peroxide is completely eliminated with the use of catalase prior to the definitive restoration

It is difficult for practitioners in clinical practice to read and assemble published information into a logical treatment philosophy, consequently a number of restorative concepts have been promulgated through a process of intuitive empiricism. For all intents and purposes operative dentistry is a skills based activity and it is understandable that practical sense-data has been accepted as valid information without appropriate certification. Procedures formerly established without the stringency of the scientific method unfortunately tend to linger in spite of incongruous evidence. The restoration of pulpless anterior teeth is a working example of empirical misconstruction that has pervaded clinical practice.

Rethinking traditional treatment In memory of Dr. William H. Liebenberg BSc, BDS (Rand) Vancouver, Canada 1955 - 2015 A founding member of our Editorial Board, Dr William Liebenberg was the inspiration behind the launch of this journal.

A gifted clinician, mentor and educator, his guidance and contribution to the dental profession globally will be sadly missed.

Ursula Jenkins, Publisher

The post-core restoration is one of the earliest restorations known to man, dating back some 3000 years to the Etruscans.1 It has been widely held that endodontic teeth required reinforcement with cast posts and cores2, presently the significance of endodontic treatment in reducing tooth strength has been questioned.3 The majority of the literature is unanimous with evidence that there is no advantage from the point of view of fracture mechanics in restoring intact root-treated teeth with posts of any form whatsoever.4,5 Nevertheless the most recent survey of US dentists found that 50% of respondents believed that a post does indeed reinforce an endodontically treated tooth.6 The restoration of an endodontically treated anterior tooth involves the restitution of esthetics and resistance to fracture. Traditionally these requisites have been accomplished with procedures ranging from veneers of composite or porcelain, to complete coverage with porcelain-fused-to-metal or all-ceramic crowns. Posts and cores, formerly regarded as the optimum foundation7, are now restricted to the severely decimated clinical crown as recent investigations confirm that the intact natural crown of an endodontically treated tooth provides maximum resistance to root fracture.8 The biological conservative alternative is to limit restoration to the restitution of lost intracoronal substance.

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Figure 1a: Preoperative view of a severely discolored central maxillary incisor subsequent to a traumatic episode and endodontic treatment some fifteen years ago.

Figure 1b: 24 hour post-walking bleach result. Note acceptable restitution of natural color.

Lower discolored pulpless teeth – a unique dilemma

iron on lysis which in turn combines with hydrogen sulfide to form a black iron sulfide compound which causes the tooth to appear darker.14 Fortunately chemical treatment of discoloration caused by the continued presence of necrotic tissue is exceptionally effective.15 It would appear from the aforementioned that bleaching discolored intact pulpless anterior teeth would be a feasible treatment option providing the bleaching does not compromise the integrity of the tooth and its supporting complex nor eliminate any future treatment options.

Treating discolored lower intact anterior teeth with indirect restorations presents a unique dilemma; the requisite tooth preparation diminishes and severely weakens the restricted mesial-distal substance of the previously intact tooth. In these instances post/core reinforcement is needed to restitute resistance form to the now compromised coronal portion of the prepared tooth. Post placement can induce internal stresses during placement and function9, notably placement in the restricted bulk and dimensions of lower incisors is not without risk.10 Ceramic restorations coupled with esthetic posts and cores provide an acceptable treatment option for patients wishing to improve the color of nonvital anterior teeth.11 Ceramic techniques, however, are costly, invasive, and require ongoing maintenance and prospective replacement. Clearly the described technique is equally effective in the upper dentition (Figure 1a and b). The case report of this paper is of the lower dentition as the single lower incisor is an esthetic challenge in that it is only rarely satisfactorily addressed with indirect restorations given that color matches of restorations to natural dentition are still problematic in clinical dentistry.12 It is unrealistic to expect that natural color can be consistently achieved with an indirect restoration given the need for an opaque layer to mask highly chromatic intrinsic stains of anterior teeth.13 In this author’s experience residual necrotic tissue is commonly found in the pulp horn remnants of discolored pulpless lower incisors. Presumably the minimal bulk of these incisors encourages minimum access with consequent incomplete extirpation. With degeneration of the pulpal remnants extravasated erythrocytes invade dentinal tubules, release

History of bleaching pulpless teeth Intracoronal bleaching of pulpless discolored teeth is a valuable treatment modality, provided that the procedures are administered with due regard for the relative risks involved. The first account of lightening a nonvital tooth dates back to 1877, when oxalic acid acted as the bleaching agent. 16 Hydrogen peroxide succeeded this technique, as reported by Harlan17 in 1884. Several techniques that aimed at activating the bleaching agent to expedite the process were then introduced,18 and in 1961, Spasser introduced his perborate technique.19 Nutting and Poe improved the perborate technique by combining it with Superoxol and described their “walking” bleaching technique in a 1963 publication.20 Since then, many articles21 proposing various combinations of previously reported materials and techniques have appeared in the literature.

There is currently little agreement as to the accepted protocol for nonvital bleaching. There is, however, consensus regarding the potential risks. Risks include

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Figure 2a: Preoperative view of a severely discolored central mandibular incisor subsequent to a traumatic episode and endodontic treatment.

Figure 2b: A resin-modified glass-ionomer seals the radicular canal from the coronal region. The patient is given a tube of 10% carbamide peroxide and instructed to flush and fill the pulp chamber every 2 hours until the desired tooth lightening is reached.

cervical resorption, fracture during the multiple treatment period, under lightening and overlightening, and the possibility of color regression. The two basic techniques are the thermocatalytic method and the walking bleaching techniques. The primary difference between the two methods is the way in which nascent oxygen is released from the chemicals. With the thermocatalytic method, various forms of heat are used to speed up the release of oxygen. Both methods have lost favor, however, because of the incidence of external root resorption.22 It is reasonable to assume, however, based on the aforementioned clinical and in vitro studies, that it is the presence of bleach in the attachment apparatus that causes local necrosis followed by inflammation and root resorption.

It is this author’s opinion that the modified method presented in this article minimizes the risks, because treatment time is reduced to days rather than weeks, as required in the original walking bleaching protocol.20

tooth. The associated risks were identified, and the modified walking bleaching technique was proposed as a costeffective, rapid, and conservative treatment option. The most favorable result would preserve the natural tooth structure and save the patient the cost and risk of an indirect restoration.

Case report An adult female patient presented with a request for a “crown” to correct the color of a discolored mandibular central incisor (Figure 2a). The tooth had previously been endodontically treated following a traumatic episode. The tooth was asymptomatic. Percussion and radiographic examination revealed a successful endodontic effort with no periapical or periodontal lesions.

Through a process of fully informed consent, the concept of intracoronal bleaching was introduced as the most conservative means of improving the color of the pulpless

Bleaching Technique The technique utilizes patient-applied carbamide peroxide and a clear custom-made splint to retain and seal the intracoronal medicament. The author has previously described this intracoronal technique.23 and subsequent publications have reported favourably on the efficacy of the protocol.24,25 10% carbamide peroxide disassociates into 3.35% hydrogen peroxide and urea26, and, therefore, the intracoronal technique is inherently harmful, given the potential for cervical root resorption. The focus of the protocol to be described is on obtaining an adequate cervical seal that will prevent the hydrogen peroxide from penetrating the root at the cementoenamel junction (CEJ) and on assuring the total elimination of residual hydrogen peroxide. The technique is remarkably simple; the patient fills the pulp chamber with carbamide peroxide and changes the solution on a 2-hourly basis until the desired whitening is achieved. The intracoronal medicament is retained with a clear, custom-made, thermoformed splint.

The appropriate preoperative preparatory steps include informed consent, with emphasis on the associated risks, radiographic evaluation of the endodontic and periodontal status, and a photographic baseline notation.

The tooth is isolated with dental dam in preparation for

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the meticulous removal of the existing intracoronal restoration (Figure 2b). Utilization of the dental dam is not mandatory, given the low causticity of carbamide peroxide; however, as with all operative options, the access rubber dam brings to the procedure is unrivaled. Single-tooth isolation, while convenient, is not recommended, because full exposure of the adjacent clinical crowns provides the clinician with crucial orientation to root angulation and inclination. This is particularly important if the radiograph reveals the presence of a tooth-colored restorative plug in the coronal portion of the obturated root canal.

The coronal restoration is removed carefully, to limit debridement to existing restorative material and residual necrotic pulp tissue. A triangular access cavity is more favourable from an operative point of view as it is the residual pulpal horns which are apt to cause discoloration.

However, recent adhesive guidelines emphasize conservation of tooth substance. Coronal gutta-percha is best removed with a controlled heating instrument, such as the Touch ‘N Heat system (Analytic Technology), which allows the nonmechanical excision of gutta-percha.

Approximately 3mm of root canal gutta-percha is removed apical to the CEJ. Measurements are made with a rubber stopper; the cavosurface margin of the access opening is used as a reference point. The objective of removing root canal gutta-percha is to create space for the restorative cervical seal and to expose dentinal tubules directed toward the cervical region of the tooth. 27 A calcium hydroxide plug, approximately 1 mm in thickness, is applied to the freshly exposed gutta-percha.

This prophylactic step aims to maintain an alkaline medium, because cervical resorption has been associated with a drop in pH at the cervical level.28 The remaining 2-mm depth of the cervical root canal access is “sealed” with one of the resin-modified glassionomer materials. Although this seal is not as crucial when carbamide peroxide is used (as opposed to 35% hydrogen peroxide), it is nevertheless crucial to seal the root canal from bacterial ingress during bleaching to prevent contamination of the gutta-percha filling (a major cause of endodontic failure).29 This author prefers Vitremer (3M Dental), because the viscosity allows precise, bubble-free application through the needle tube applicator of a Centrix syringe (Centrix).

Rotary instrumentation is used to “refresh” the interior of the pulp chamber, to expose coronal dentinal tubules that were inadvertently sealed during priming and application of the restorative plug. Liquid orthophosphoric acid is used to

Figure 2c: Once the desired tooth whitening has been achieved the patient returns for the definitive composite resin restoration. Catalase is applied intracoronally to eliminate the hydrogen peroxide residues.

Figure 2d: The composite resin final lingual increment is contoured with a sable artists brush.

Figure 2e: Polymerization of intracoronal composite resin initiated from the facial with glycerine gel applied to lingual surface.

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flood the inside of the access cavity for 15 seconds to remove the smear layer. Acid etching will open the dentinal tubules facilitating greater and faster diffusion of the radicals through the dentin. 21 A soft splint is fabricated on a working cast and trimmed to the dimensions of a custom sports mouthguard (to approximate the attached gingiva buccally and a portion of the lingual mucosa. The patient is given a tube of neutralpH, 10% carbamide peroxide and instructed to fill the pulp chamber every 2 hours until the desired tooth lightening is reached. A 10-mL Monoject syringe (Sherwood Medical) is used to flush the pulp chamber with warm water prior to replenishment of the carbamide peroxide gel. The patient rehearses the placement of the 10% CP in the office. The splint is used to retain the bleaching agent and to prevent ingress of debris into the access cavity. In addition, the splint serves as a reminder to the patient that full incisal and torquing functions are to be avoided while the tooth is in its hollow, unrestored state.

The patient is cautioned as to the celerity of the response, and the consequent potential for overbleaching is stressed.

Mild-to-moderate (two to four shade guides darker than the adjacent teeth) color variances generally require five to eight applications at 2-hour intervals. Patients are encouraged to limit applications to daylight hours, when reliable assessments of color can be made. Continual nighttime applications are reserved for severely discolored teeth.

Facial enamel bleaching is seldom required; however, the bleaching tray does facilitate the traditional bleaching protocol, should it be considered necessary. The access cavity is restored with a dentin-colored resin composite once satisfactory color shift has been accomplished.

Importance of final restoration Bleaching with carbamide peroxide relies on an oxidationreduction reaction to change the color of teeth. The free radicals perhydroxyl and oxygen diffuse through the dentinal tubules and break down the double bonds in the chromophore structure of organic molecules to produce simpler molecules, which have less absorption energy and effectively reflect less light, thereby producing the whitening effect. This reaction will ultimately reach a saturation point and the bleaching effect ceases. This chemical reaction is believed to be a permanent alteration although some bleached teeth do discolor after varying periods of time.

This “relapse” is thought to be the result of microleakage of the restoration in the access cavity and not reduction of previously oxidized chromophores.30 It is vitally important

Figure 2f: Final postoperative result. Note complete disappearance of discoloration and restitution of natural opalescence.

that the definitive restoration be meticulously delivered with full regard for marginal integrity and longevity of the seal at the restorative tooth interface.

The splint is removed, and the access cavity is flooded with water from a three-in-one syringe in preparation for resin composite shade selection. This is done with out dental dam. An uncured increment of resin composite is inserted into the pulpal chamber, and the effect on the overall color is noted. This resin composite mockup is repeated until the appropriate dentinal shade is selected.

The tooth is isolated with dental dam in preparation for the definitive restoration. Swift reported that the primary cause of reduced bond strength following bleaching is probably the presence of residual peroxides or oxygen, which interferes with polymerization of resin bonding systems and restorative materials.31 The definitive restorative procedure therefore must include the removal of residual hydrogen peroxide.

Previous research has shown that water rinses of the pulp chamber immediately after bleaching may not effect rapid neutralization of the residual toxic peroxides.32 The most recent walking bleaching guidelines27 have recommended that the pulp chamber be obturated with a calcium hydroxide and water paste, which is left in the chamber for 7 days. This procedure is intended to render neutral the pH in the cervical region of the tooth, offering adequate means of repair to any possible damage to the cervical periodontal ligament. This time period between bleaching and restoration is also advocated to allow the elimination of residual oxygen capable of interfering with the resin polymerization process.33 The use of a neutral-pH

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carbamide peroxide solution together with the use of an enzyme to eliminate hydrogen peroxide obviates the need for an interim dressing and facilitates immediate restoration.

Catalase, also known as H2O2 oxidoreductase, is an essential enzyme for the proper functioning of the body’s defense mechanism. Catalase acts by promoting the reactions involved in the decomposition of hydrogen peroxide to water and oxygen.34 Catalase changes two molecules of H2O2 to two molecules of H2O and O2.

Because it is an enzymatic reaction, the rate is rapid (it accelerates the decomposition by more than 100 million– fold), and practically independent of temperature, with a broad optimum pH. It has been shown that application of catalase to teeth immediately after bleaching eliminated the hydrogen peroxide residues and prevents their radicular penetration.34 This author uses a sponge pledget to apply the catalase, leaves the pledget in situ for a period of 3 minutes (Figures 2c), and then flushes the pulp chamber with water for 2 minutes. The pulp chamber (dentin and enamel) and cavosurface margin of the access cavity are acid etched for 15 seconds with 37% phosphoric acid and treated according to the chosen adhesive protocol. It is recommended that an acetone-based adhesive system (such as Prime& Bond NT, Dentsply) be used, because these solvents have previously been shown to reverse the adverse effects of bleaching on enamel bond strengths.35 Recent literature has shown no such reversal using ethanol based dentin adhesive.36 The previously selected (prior to dental dam application) resin composite is incrementally added (Figure 2d) and polymerized from the facial surface.(Figure 2e). The longevity of the color correction achieved by this modified walking bleach technique is reliant upon the quality of the lingual restoration rather than the bleaching procedure itself. A baseline radiograph must be obtained to accredit annual evaluation. If a cervical inflammatory process is diagnosed, calcium hydroxide therapy must be started immediately.27

Discussion It has been suggested that hydrogen peroxide may cause damage to the tooth and surrounding attachment apparatus.37 In addition, the resorptive potential of residual hydrogen peroxide has highlighted the importance of preventing hydrogen peroxide from penetrating the root through to the attachment apparatus.

The focus of the protocol of this article has therefore been on obtaining an adequate cervical seal. An understanding

of the anatomic complexities of the attachment apparatus is crucial when the objective of the cervical seal is accepted as being to physically block the passage of the bleaching agent from within the tooth to the root surface.

Essentially, the passageway from the bleach-filled root canal to the connective tissue cells of the periodontal tissues is the dentinal tubular system. These tubules course apically as a sigmoid curve from the root surface or dentinoenamel junction to the canal wall. Selection of the appropriate anatomic locality of the cervical seal is therefore essential.

Often, bleaching efforts are applied to adolescent patients, in whom passive eruption affects the cementodentoenamel junction and makes assessment difficult. The level of attachment is generally curvilinear, rather than linear, and coincides with the level of the supporting bone. In health, the level of attachment is more coronal at the lingual aspect than at the facial aspect.

Potentially a linear seal may adequately block the facial dentinal passageways but still leave the lingual dentinal tubules patent. Although diligence in the selection of the locality of the cervical seal is paramount, irrespective of the age of a patient, the patency38 and permeability39 of the tubule lumen decrease with age. Because cementum can act as a deterrent to the diffusion of hydrogen peroxide40 it is pertinent to note that its permeability41 decreases and its thickness increases42 with age. Thus, it is clear that provision of an adequate cervical seal is critical especially in adolescent patients.

The main benefit of the prescribed technique is that a less concentrated solution of unheated peroxide is utilized.

This has potential safety consequences for both office staff and patients. Repeated replenishment allows for a rapid technique that is far more convenient and cost effective than the traditional walking bleaching technique. The disadvantage relates to patient compliance, because it is essentially a patient-applied technique that requires that the patient return for a final restoration. Overbleaching can be of concern; however regression, as with all toothbleaching procedures43 can be expected 1 or 2 weeks after a bleaching regimen is completed. Unlike the traditional walking bleaching technique, this method allows the patient to discontinue refilling the pulp chamber once the desired color has been reached. If overbleaching occurs, the bleaching tray can be utilized in the conventional manner to apply carbamide peroxide to the facial surfaces of the adjacent teeth to correct the color mismatch (Figure 2f).

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Further research Because of the small number of teeth treated over the past 12 years, no definitive prognosis can be drawn from the limited, though impressive, results to date. Bizhang and others from Humboldt-University Berlin, Germany recently completed a clinical study comparing the effectiveness of various bleaching techniques.44 Their study included the previously published modified walking bleach technique of this author.23 Sixty discolored, non-vital teeth were divided into three groups and treated with one of the bleaching materials and methods The results showed that the technique described in this paper produced a significantly better post-bleaching, whitening effect than other techniques. At six months the technique was as effective as the sodium perborate mixed with 3% hydrogen peroxide technique.

Summary A modified walking bleaching technique that relies on patient-administered intracoronal carbamide peroxide has been presented. Notwithstanding the fact that the hydrogen peroxide is administered in a neutral and less concentrated solution, the emphasis of the operative description has been on assuring the complete elimination of residual hydrogen peroxide in an effort to minimize the resorptive complications of previous dentist-applied nonvital bleaching protocols.

Teeth that are recently discolored as a result of pulpal breakdown appear to have an excellent prognosis when the modified walking bleaching technique is used.

The advantage of the described technique is the conservation of the intact tooth structure which avoids the need for a traditional cast post-core and laboratory fabricated restoration. The form and function of the tooth is unaltered with no change in natural occlusion.

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2. Kantor ME, Pines MS. A comparative study of restorative techniques for pulpless teeth. J Prosthet Dent 1977;38:405-412.

3. Hunter AJ; Hunter AR. The treatment of endodontically treated teeth. Curr Opin Dent 1991 Apr;1:199-205.

4. Stockton LW, Williams PT, Clarke CT. Post retention and post/core shear bond strength of four post systems. Operative Dentistry 2000;25:441-447.

5. Bogert MC, Boston DW. Use of an existing post to rerestore an enodontically treated tooth with a new post-and-core complex and crown: a case report. Quintessence Int 2000;31:129-132.

6. Morgano SM, Hashem AF, Fotoohi K, Rose L. A nationwide survey of contemporary philosophies and techniques of restoring

endodontically treated teeth. Jnl Prosth Dent 1994;72:259-267.

7. Album MM; Lloyd RW . Technique for restoring endodontically treated anterior teeth with precision posts and porcelain-bonded-to-gold crowns. J Am Dent Assoc 1976 Sep;93:591-6.

8. Sidoli GE, King PA, Setchell DJ. An in vitro evaluation of a carbon fibre-based post and core system.

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10. Sirimai S; Riis DN; Morgano SM. An in vitro study of the fracture resistance and the incidence ofvertical root fracture of pulpless teeth restored with six post-and-coresystems. J Prosthet Dent 1999 Mar;81:262-9.

11. Quintas AF, Dinato JC, Bottino MA. Aesthetic posts and cores for metal-free restoration of endodontically treated teeth. Prac Periodont Aesthet Dent 2000;12:875-884.

12. Wee AG, Kang EY, Johnson WM, Seghi RR. Evaluating porcelain color match of different porcelain shade matching systems. J Esthet Dent 2000;12:271-280.

13. Okuda WH. Using a modified subopaquing technique to treat highly discolored dentition. JADA 2000;131:945-950.

14. Walton R. Bleaching discolored teeth: Internal and external. In: Principles and Practice of Endodontics. 1st. ed. Philadelphia, PA: W.B. Saunders 1989;385-400.

15. Miara P. Aesthetic Treatment of discoloration of nonvital teeth.

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16. Chapple JA. Restoring discoloured teeth to normal. Dent Cosmos 1877;19:499.

17. Harlan AW. The removal of stain from teeth caused by administration of medicinal agents and the bleaching of pulpless teeth.

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18. Prinz H. Recent improvements in tooth bleaching. Dent Cosmos 1924;66:558.

19. Spasser HF. A simple bleaching technique using sodium perborate. NYState Dent J 1961;27:332-334.

20. Nutting EB, Poe GS. A new combination for bleaching teeth. J South Calif Dent Assoc 1963;31:289-291.

21. MacIsaac AM, Hoen MM. Intracoronal bleaching: Concerns and considerations. J Can Dent Assoc 1994;60:57-64.

22. Friedman S, Rotstein I, Libfeld H, et al. Incidence of external root resorption and esthetic results in 58 bleached pulpless teeth. Endod Dent Traumatol 1988;4:23-26.

23. Liebenberg WH. Intracoronal lightening of discolored pulpless teeth: A modified walking bleach technique. Quintessence Int 1997;28:771-777 24. Vachon C, Vanek P, Friedman S. Internal bleaching with 10% carbamide peroxide in vitro. Practical Periodontics and Aesthetic Dentistry 1998;10:1145-1148.

25. Caughman WF, Frazier KB, Haywood VB. Carbamide peroxide whitening of nonvital single discolored teeth: Case reports.

Quintessence Int 1999;30:155-161.

26. Marshall MV, Cancro LP, Fischman SL. Hydrogen peroxide: a review of its use in dentistry. J Periodontol 1995;66:786-796.

27. Baratieri LN, Ritter AV, Monteiro S, de Andrada MAC, Vieira LCC. Nonvital tooth bleaching: Guidelines for the clinician.

Quintessence Int 1995;26:597-608.

28. Nerwich A, Figdor D, Endo D, Messer HH. PH changes in root dentin over a 4-week period following root canal dressing with calcium hydroxide. J Endod 1993;19:302-306.

29. Limkangwalmongkol S, Abbott PV, Sandler AB. Apical dye penetration with four root canal sealers and gutta-percha using longitudinal sectioning. J Endodont 1992;18:535-539.

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30. Abbott PV. Aesthetic Considerations in Endodontics: Internal Bleaching. Prac Periodont Aesthet Dent 1997;000;9:833-840.

31. Swift EJ. Restorative considerations with vital tooth bleaching. J Am Dent Assoc 1997;128:60S-64S. 32. Torneck CD, Titley KC, Smith DC, Adibfar A. Effect of water leaching on the adhesion of composite resin to bleached and unbleached bovine enamel. J Endod 1991;17:156-160.

33. Titley KC, Torneck CD, Smith DC, et al. Adhesion of composite resin to bleached and unbleached bovine enamel. J Dent Res 1988;67:1523-1528.

34. Rostein I. Role of catalase in the elimination of residual hydrogen peroxide following tooth bleaching. J Endod 1993;19:567569.

35. Barghi N, Godwin JM. Reducing the adverse effect of bleaching on composite-enamel bond strength. J Esthet Dent 1994;6:157-161.

36. Spyrides GM, Perdigão J, Pagani C, Araújo MAM, Spyrides SMM Effect of Whitening agents on dentin bonding. J Esthet Dent 2000;12:264-270.

37. Boksman L, Jordan RE, Skinner DH. Non-vital bleaching— internal and external. Aust Dent J 1983;28:149-152.

38. Scott JH, Symons NBB. Introduction to Dental Anatomy, ed 8.

Edinburgh, Churchill Livingstone, 1977:218.

39. Kraus BS, Jordan RE, Abrams L. Dental Anatomy and Occlusion.

Baltimore, MD: Williams & Wilkins, 1969:160.

40. Rotstein I. Effect of cementum defects on radicular penetration of 30% H2O2 intracoronal bleaching. J Endod 1991;17:230-233.

41. Blayney JR, Wasserman F, Groetzinger G, et al. Further studies in mineral metabolism of human teeth by the use of radioactive isotopes. J Dent Res 1941;29:559.

42. Zander HA, Herzeller B. Continuous cementum apposition. J Dent Res 1958;37:1035.

43. Haywood VB. Achieving, maintaining, and recovering successful tooth bleaching. J Esthet Dent 1996;8:31-38.

44. Bizhang M, Heiden A, Blunck U, Zimmer S, Seemann R, Roulet JF.Intracoronal bleaching of discolored non-vital teeth. Oper Dent.

2003 Jul-Aug;28(4):334-40.

The ethics of patient care Dr William H Liebenberg (Canada), BSc, BDS, (Rand) Most of us accept the epistemological fact that our intellectual and investigative resources are limited given the immensity of the ever expanding dental lore and the restrictive limits of time. We have to readily acknowledge that our beliefs are inextricably reliant upon the intelligence, accuracy and selflessness of others. In fact, the more educated we become, the more our beliefs come to us distilled through the authority of others.

In the dental profession an established conduit for post secondary education has been the written and spoken word, the veracity of which has traditionally been accepted with faith. While attending a recent dental symposium, I was struck by the absence of veritable teachers amongst the featured speakers. Teaching is no longer the exclusive domain of the aspiring tenured educator; rather, the self promoting sum and substance of the entrepreneurial spirit has chartered a new route. The entrepreneurial spirit has venerated anecdote, nourished the dis-semination of biased information and legitimized the métier of information spinning.

To understand the deprecating worth of the information spin it is important to remember that the instruction gleaned through the continuing education conduit forms the basis of patient care. As such, the trustworthiness of information is becoming increasingly significant as clinicians utilise the data to establish their belief parameters and decide on which authority to assimilate. It is therefore appropriate to examine the motivation behind the current continuing education effort. Clearly, there are individuals who truly love to teach and do it for no other reason than the common good and personal gratification. Others are motivated by the

accompanying academic honour and peer acceptance. Some individuals, on the other hand, do it for the indirect financial rewards as they utilise their publications to further patient confidence (and treatment acceptance), promote their education profile (and lecture schedule), and most shamefully of all, when delivered without disclosure, to promote institutions and other commercial ventures with which they are financially affiliated.

Given the allure of these enticements, it would seem logical that something has to be done to protect the profession from the untoward effects of self promotion masquerading as science.

Clinicians deserve to be informed of the validity of information to avoid premature application of inappropriate techniques, materials and biased interpretations of un-warranted assumptions. The information spin must stop. It is worth noting that the ethics of patient care requires that we believe a given proposition to be true, not merely that we wish it were so (self etching primers etch sclerotic and reparative dentin sufficiently to allow for predictable long term resin bonds. I, for one, wish that were true but research refutes the whimsy).

Our clinical experience reveals that we cannot help but value evidence and demand that treatment propositions, materials and procedures manifestly cohere. The ethics of patient care demand that our beliefs rest on information which is based on sound scientific principles devoid of bias, inaccuracies, mis-representation (speculation misrepresented as fact!) and harmful practices.

We must find our way back to a time when patient care based solely upon faith in the absence of evidence, dishonours those who surrender to it.

Information is null if devoid of truth.

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Does bruxism contribute to dental implant failure?

Johan Hartshorne1

A critical appraisal of a systematic review: Zhou Y, Gao J, Luo L, Wang Y. Does bruxism contribute to dental implant failure? A systematic review and meta-analysis. Clinical Implant Dentistry and Related Research 2015 doi: 10.1111/cid.12300 Article first published online: 2 March 2015 Origin of research – Wuhan University, Wuhan, China

Summary Systematic review conclusion: The meta-analysis suggests that bruxism is a contributing factor towards the occurrence of dental implant technical/biological complications and plays a role in dental implant failure. Prostheses in bruxers presented with a higher failure rate compared to non-bruxers.

Critical appraisal conclusion: The results suggest that bruxism could be associated with implant complications biological and/or technical). The findings also suggest that the likelihood that a biological (implant failure) or a mechanical (prosthesis failure) complication could occur was almost four times greater in bruxers compared to nonbruxers. Prostheses are more likely to fail (porcelain chipping and fractures, screw loosening and fractures) in bruxers compared to non-bruxers. These findings should however be interpreted with caution due to the poor level of evidence presented in this review.

Implications for clinical practice: Current expert opinion suggests that clinicians adopt a cautious approach based on measures that can assist in reducing the harmful effects of occlusal forces that are developed and transmitted to peri-implant bone and implant assisted prostheses during tooth-grinding and tooth-clenching. Measures that should be taken in consideration are the surgical (bone quality, number, size and position of implants), prosthetic (timing of loading, flatter cuspal planes, greater freedom of movement at the occlusal contact areas, splinting and avoiding cantilevers and nonaxial loads) and preventive (use of a hard protective occlusal splint during night-time) aspects of implant therapy.

Clinical question Johan Hartshorne B.Sc., B.Ch.D., M.Ch.D, M.P.A. Ph.D. (Stell), FFPH.RCP (UK), Visiting Professor, Department of Periodontics and Oral Medicine, University of Pretoria, Pretoria, South Africa.

1

E-mail: jhartshorne@kanonberg.co.za

Is there a relationship between bruxism and dental implant failure?

Review methodology The authors conducted a systematic search of the MEDLINE (PubMed) and EmBase database in November 2013 (start and end date not indicated) without time and language restrictions. Potential studies had to meet the following eligibility criteria to be included in the review: (i) participants receiving dental implant treatment; (ii) presence of bruxism (clenching or grinding of the teeth, and bracing or thrusting of the mandible) (iii) dental implant failure (biological and/or biomechanical); and (iv) studies had to be designed as cohort studies (bruxers vs non-bruxers); and follow-up of the

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prosthesis at least 1 year in function. Laboratory and animal studies as well as duplicated studies were excluded from the meta-analysis. A hand searching off all the relevant references of included studies were also conducted to identify further potential studies. The primary outcome measured was technical failure (fracture: porcelain/screw/ implant; loosening: screw/implant; losing of retention/ implant). The quality of retrieved cohort studies was assessed using the Newcastle-Ottawa Scale (NOS) tool.1 Selection of studies, data extraction and assessment of methodological quality was performed independently by two reviewers.

Disagreement was resolved through consulting a third reviewer.

Due to different units of analysis used in the primary studies, collected data were classified into two groups based on number of prostheses (Group A) or number of patients (Group B). Within each group a subgroup analysis was performed for primary studies reporting on outcomes: (i) ceramic chipping and fractures; (ii) implant loss; and (iii) other mechanical failures such as screw loosening and fractures, respectively. Odds ratio (OR) with 95% confidence interval (CI) was pooled to estimate the relative effect of bruxism on dental implant failures (complications). Statistical analysis was performed using the fixed effects model. Where heterogeneity was high, the random effects model was used.

The Cochran’s Q and I2 statistic was used to test heterogeneity across studies.

Main results Study characteristics Seven cohort studies were included in this meta-analysis. In Group A, 1788 prostheses were placed in patients, and 509 prostheses were in bruxers. In Group B a total of 445 participants were included of which 81 patients had a history of bruxism. Most participants were older than 50 years old. The mean duration of follow-up time for each study ranged from 1 to 10 years.

The NOS assessment suggests that the included studies had acceptable quality.Thus according to this assessment the representativeness of the exposed/non-exposed cohort, outcome assessment, length of follow-up time, and adequacy of follow up were of good quality and had low risk of bias.

A statistically significant relationship was found between bruxism and dental implant related failures (biological implant failure and mechanical prostheses complications). In group A (prostheses is unit of analysis) the total pooled OR of bruxers versus non-bruxers for all subgroups was 4.72 (95% CI: 2.66–8.36, p = 0.0001). In group B (patient is

unit of analysis), the total pooled OR of bruxers versus nonbruxers for all subgroups was 3.83 (95% CI: 2.12– 6.94, p = 0.0001).

Subgroup analysis for outcomes (i) ceramic fractures or chipping; (ii) implant loss; and (iii) other mechanical failures (i.e. screw loosening or fracture) showed the same relationship in both group A and B. All the outcomes in the subgroup analysis were statistically significant except implant loss in Group B (p= 0.30).

Among all the complications, ceramic (or porcelain) chipping (or fracture) had a higher failure rate than the others.

Conclusion The meta-analysis suggests that bruxism is a contributing factor towards the occurrence of dental implant technical/biological complications and plays a role in dental implant failure. Prostheses in bruxers presented with a higher failure rate compared to non-bruxers.

The authors declared that there was no potential conflict of interest with respect to the authorship and/or publication of this review.

Commentary Background and importance Bruxism is an umbrella term used for clenching and grinding of teeth occurring without a functional purpose (non-functional motor activity). It can occur during sleep (sleep bruxism) or during wakefulness (awake bruxism). It is considered as one of the most frequent of the many parafunctional activities that has a potential for causing damage to the stomatognathic system.2 Bruxism is often cited as a risk factor for implant failure, both biological and mechanical, on the basis that the forces transmitted to the parts of the implant system during bruxing activities can result in overloading of the mechanical and biological components of the implant system, resulting in occlusal surface wear fracture, loosened screws, or abutment and implant fracture.3,4,5 Much still remains unclear, conflicting and controversial about the definition, etiology, and diagnosis, of bruxism and its relationships with the stomatognathic system, and with dental implants and its superstructures in particular.5,6,7 Most authors agree that bruxism is primarily a disorder of central origin (e.g., sleep arousal responses, stress, anxiety) with a lesser importance placed on the role peripheral origin (e.g., occlusal factors). It is hypothesized that one or more factors (stress, anxiety, genetics, neurochemical responses, sleep arousal response, factors linked to quality of sleep, oral and

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dental anatomy) may, in different ways and to different degrees contribute to increasing frequency, duration and intensity of normal masticatory muscle activity during sleep or wakefulness, thus resulting in increased loading forces and cycles.8 It also hypothesized that the increased loading forces on implants and their superstructures in bruxers combined with the reduced proprioceptive feedback and give from the absence of periodontal ligament around implants could cause biological and mechanical complications, thus resulting in implant and prostheses failure.6,9 A recent systematic review suggests that bruxism may be a risk factor for mechanical complications in implant prostheses (porcelain chipping and fractures, screw loosening and fractures), but unlikely to be a risk factor for biological complications around implants.10 Are the results valid?

This review presented with several limitations increasing the risk of bias that may potentially influence the quality of the data. The primary study designs and research methodology were generally of a very low quality based on investigating non-representative samples, characterized by analyzing convenient cohort groups in academic institutions [prospective (4) and retrospective (3)], small sample sizes, lacking control groups and no sampling strategy. Such flaws could affect the external validity of the findings and the consistency of the data.

Cohort studies are generally easily affected by various biases compared to experimental research designs.

Participants in the included studies varied with regards to type of implant and prostheses. Prostheses varied from CAD/CAM designed full arch prostheses to single tooth restorations and screw retained or cement-retained. The type of implant system used, number of implants, in which jaw they were placed and the loading protocol also varied significantly within and between studies.

The diagnostic criteria for bruxism were inadequately defined or lacking in several of the included primary studies and therefore a serious limitation. Different diagnostic strategies were used in the primary studies. At present validated diagnostic criteria exist only for sleep bruxism and should be based on polysomnography recordings in a controlled laboratory setting.7 No definitive validated criteria as yet, exists for measuring bruxing activities during wakefulness. Other diagnostic complexities such as the frequency, degree of intensity and duration of bruxism was not recorded in the primary studies, thus the effect thereof

could not be assessed in this review.

The presence of co-morbid conditions such as physical or psychological conditions, smoking, use of drugs, type of prostheses, occlusion scheme, opposing dentition and presence of cantilevers in prosthetic restorations were not taken into consideration. These confounding variables may have a potential influence on the frequency, intensity and duration of bruxism and/or the prevalence of biological and technical complications (failures) with dental implants and/or prostheses.

On the positive side, the results showed consistency in the estimates of effect in the two groups as well as the subgroups, irrespective of the heterogeneity in study design, variety of patients and taking the sensitivity analysis into consideration. On the negative side, heterogeneity may introduce ambiguity into the synthesis of the evidence. Poor study design, heterogeneity of participants, inconsistency and inaccuracies in the research methodology, and lack of controlling confounding factors potentially increases the risk of bias resulting in poor quality of evidence and thus reducing the validity of the results. The findings from this review should therefore be interpreted with caution.

What were the key findings?

Disregarding the poor quality of the evidence and based on the estimated odds ratios, the following key findings can be made regarding the relationship between bruxism and implant complications/failures (biological and/or technical).

The results suggest that bruxism could be associated with implant complications biological and/or technical). In general, the likelihood that a biological (implant failure) or a mechanical (prosthesis failure) complication could occur was almost four times greater in bruxers compared to non-bruxers.

Prostheses are more likely to fail (porcelain chipping and fractures, screw loosening and fractures) in bruxers compared to non-bruxers. These findings should however be interpreted with caution within the context of the poor level of evidence available and presented in this review.

How are the results of this review applicable in clinical practice?

The estimates of OR (the likelihood or odds that an outcome (implant or prosthesis failure) will occur given a particular exposure (bruxism or non-bruxism) were very consistent in both groups and subgroup analysis. This consistency across studies of various types in a variety of patients may increase the applicability of the findings in clinical practice.

However, current expert opinion suggests that clinicians

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adopt a cautious approach based on measures that can assist in reducing the harmful effects of occlusal forces that are developed and transmitted to peri-implant bone and implant assisted prostheses during tooth-grinding and toothclenching. Measures that should be taken in consideration are the surgical (bone quality, number, size and position of implants), prosthetic (timing of loading, flatter cuspal planes, greater freedom of movement at the occlusal contact areas, splinting and avoiding cantilevers and non-axial loads) and preventive (use of a hard protective occlusal splint during night-time) aspects of implant therapy.”

Clinical Resolution The research data is fragmented by the heterogeneity of study populations, diverse confounding exposures, varying diagnostic strategies for bruxing, different surgical and prosthetic implant interventions, and poor study design, thus influencing the quality of the evidence. However, the consistency in the findings within and across primary studies increases the confidence in the estimates of OR that bruxism may be associated with increased biological and mechanical failures or complications in implants and the prostheses respectively. These findings should however be interpreted with caution within the context of the poor level of evidence available and presented in this review. Bruxism remains a potential risk factor; therefore clinicians should adopt a cautious approach when planning for implantassisted prostheses in bruxers.

This review has illustrated the vast need for well-designed studies for both the etiology of bruxism and its purported relationship with implant failure.

Disclosure and Disclaimer Dr Johan Hartshorne is trained in clinical epidemiology, biostatistics, research methodology and critical appraisal of research evidence. This critical appraisal is not intended to, and do not, express, imply or summarize standards of care, but rather provide a concise reference point for dentists to

aid in understanding and applying research evidence from referenced early view or pre-published articles in top ranking scientific publications and to facilitate clinically sound decisions as guided by their clinical judgement and by patient needs.

References 1. Wells GA, Shea B, Connell DO. The Newcastle-Ottawa Scale (NOS) for assessing the quality of non-randomized studies in meta-analyses. Ottawa, ON: Ottawa Hospital Research Institute, 2009. http://www.ohri.ca/programs/clinical_ epidemiology/oxford.asp.

2. Manfredini D, Lobbezoo F. relationship between bruxism and temporo- mandibular disorders: a systematic review of literature from 1998 to 2008. Oral Surg Oral Med Oral Pathol, Oral Radiol Endod 2010; 109: e26-e50.

3. Tosun T, Karabuda C, Cuhadaroglu C.Evaluation of Sleep Bruxism by Polysomnographic Analysis in Patients with dental implants. Int J Oral Maxillofac Implants 2003; 18: 286-292.

4. Lobbezoo F, Brouwers JEIG, Cune MS, Naeije M. Dental implants in patients with bruxing habits. J Oral Rehabil 2006; 33: 152-159.

5. Manfredini D, Bucci MB, Sabatttini VB, Lobbezoo F. Bruxism: Overview of current knowledge and suggestions for dental implant planning. J Craniomand Prac 2011; 29: 304-312.

6. Lobbezoo F, Van Den Zaag J Naeije M. Bruxism: its multiple causes and its effects on dental implants – an updated review. J Oral Rehabil 2006; 33: 293-300.

7. Manfredini D, Winocur E, Guarda-Nardini L, Paesani D, Lobbezoo F. Epidemiology of Bruxism in adults: a systematic review of the literature. J Oropfacial Pain 2013; 27: 99 – 110.

8. Balshi TJ, Hernandez RE, Pryszlak MC, Rangert BA. Comparative study of one implant versus two replacing a single molar. Int J Oral Maxillofac Implants 1996;11:372–378.

9. Hämmerle CH, Wagner D, Brägger U. Threshold of tactile sensitivity perceived with dental endosseous implants and natural teeth. Clin Oral Implants Res 1995; 6: 83–90.

10. Manfredini D, Poggio CE, Lobbezoo F. Is bruxism a risk factor for dental implants: A systematic review of the literature.

Clin Impl Dent Rel Res 2014; 16: 460-469.

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CASE REPORT

Rationale for the suggested use of fibre post segments in composite core buildups for endodontically treated teeth Leendert Boksman,1 Gary Glassman2

Dr Leendert (Len Boksman) DDS, BSc, FADI, FICD, is retired and a free lance consultant to various dental manufacturers.

He can be reached at lenpat28@gmail.com

1

Dr Gary Glassman DDS, FRCD(C) The author of numerous publications, Dr Glassman lectures globally on endodontics, is on staff at the University of Toronto, Faculty of Dentistry in the graduate department of endodontics, and is Adjunct Professor of Dentistry and Director of Endodontic Programming for the University of Technology, Kingston, Jamaica.

He can be reached at gary@rootcanals.ca.

The restoration of teeth utilising composites still presents a myriad of clinical challenges for the dental clinician. This is especially true for extensively broken down teeth and as well, those teeth which have been accessed endodontically. Fibre posts such as the quartz Macro-Lock Illusion X-RO post (Recherches Techniques Dentaires—RTD) UniCore Fiber post (Ultradent), and DT Light-Post (RTD) are now the posts of choice for a direct one appointment restoration of the severely compromised endodontically treated tooth.

Current research supports the use of an etch and rinse bonding protocol, with a compatible bonding agent, utilising a dual-cured composite cement that can be utilised for the core as well (Cosmecore—Cosmedent; CoreCem—RTD; Zircules—Clinician’s Choice) for best results.1,2 Traditionally, minimally accessed endodontically treated teeth that are not extensively compromised by caries or fracture, have been restored solely with a composite core, without the placement of a post. This decision must be based on the amount of tooth structure left, and if a full coverage restoration is to be placed now or in the future. The width and height of the ferrule remaining is critical to restorative success (Figs. 1a & b),3-6 as well as the number of tooth walls left, post preparation, which significantly affects the long-term restorative outcome (Fig. 2).6-8 In a review of 41 articles published between 1969 and 1999 (the majority from the 90s), Heling states that ‘the literature suggests that the prognosis of root canal-treated teeth can be improved by sealing the canal and minimising the leakage of oral fluids and bacteria into the peri-radicular areas as soon as possible after completion of root canal therapy.’9 A similar review by Saunders et al also concluded that coronal leakage of root canals is a major cause of root canal failure.10 Sritharan states that ‘it has been suggested that apical leakage may not be the most important factor leading to the failure of endodontic treatment—but that coronal leakage is far more likely to be the major determinant of clinical success or failure.’11 Coronal microleakage can occur due to a deficient final restoration (due to resultant microleakage from polymerisation contraction, cement wash out, poor full coverage, flex etc) and resultant secondary caries.12

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1a

1b

2

Fig. 1a: Schematic diagram of a molar with conservative access opening, which when restored with a core only, will leave sufficient width and height of dentin to act as a ferrule resisting failure.

Fig. 1b: The same tooth with a widely divergent access opening, restored with Macrolock posts and composite core, when prepared for a full coverage restoration will not leave sufficient dentine (no ferrule), resulting in a stand-alone core which will drastically influence failure rate.

Fig. 2: Schematic diagram of the molar in Figure 1a, but with Macrolock Fiber Post segments as inserts to decrease composite volume and increase polymerisation factors.

Polymerisation contraction (shrinkage) Many different types of composites are now available to the practitioner including microfills, macrofills, hybrids, and small particle hybrids, nanofills, nanohybrids, or microhybrids.13 Even though the formulations can be adjusted in handling to make these composites ‘packable’, ‘flowable’, or ‘sculptable’, polymerisation shrinkage or contraction stress is still the most important clinical challenge or problem associated with their use.14,15 This shrinkage or contraction and the stress created varies from composite to composite, and can be affected by: its filler type and loading content, the resin matrix and its molecular weight, the shade and opacity, the cavity preparation shape (C-Factor) width and depth, the composite thickness, the elastic modulus of the composite and tooth, the irradiance level and curing time, the spectral output of the curing light, the curing light placement, bulk or incremental fill, the rate of force development (high irradiance lights), the initiator system used, and the degree of conversion.16-25 In published studies, shrinkage values for various composites have been reported from 2.00 to 5.63 vol. per cent,26 and 1.67 to 5.68 per cent,27 with flowables demonstrating the highest shrinkage with a contractions stress measurements ranging from 3.3 to 23.5MPa.26 Not all composites advertised as low-shrinkage actually have reduced polymerisation shrinkage measurements. When evaluating seven low-shrink BisGMA-

based composites, Aelite LS Posterior and N’Durrance presented relatively high shrinkage values.28 The polymerisation contraction of the composite resin and contraction stress created, as discussed previously, can produce tensile forces on the tooth structure and the bonding system that may not only disrupt the bond to the cavity walls,29,30 but also fracture enamel along the prisms (white line margins).31 This failure can lead to caries, sensitivity in vital teeth, and microleakage, allowing the penetration of bacteria, fluids and toxins which can negatively affect the success of endodontic treatment (coronal leakage). 32 Braga et al state that ‘shrinkage stress development must be considered a multi-factorial phenomenon’ and that ‘the volume of the shrinking composite becomes a variable to be considered’.33 Unterbrink and Liebenberg in their publication state that shrinkage stress increases with increasing C-Factor and that the size of the restored cavity is an important factor when bulk filling.34 Their study35 also shows that incremental filling lowers the C-Factor and that it is better than bulk cure because of better adaptation to the cavity wall, decreasing microleakage and increasing the degree of conversion. In a study looking at microleakage and cavity dimensions, it was found that microleakage seemed to be related to a restoration’s volume, but not to its C-Factor.36 With bulk filling techniques, the hardness or conversion of composites are significantly lower than those of the same material placed

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Fig. 3: Radiographic presentation of a patient with pain in the lower left second molar, which has been minimally restored.

Fig. 4: The clinical presentation of the second molar which would demonstrate sufficient tooth structure remaining after root canal treatment so that a fibre post and core is not required.

with the incremental technique.37 Watts et al38 recommend that the restorative mass must be equally considered when translating shrinkage science into specific clinical recommendations.

So where does this lead us in a suggested modification of our restorative technique for placing a core in an endodontically treated tooth? Currently, when there are enough walls and tooth structure left, many clinicians insert a bulk fill, dual-cure composite resin into the endodontic access opening (the same material as that used for cementing the fibre post) and then cure it all at once with an LED curing light. As already mentioned, this bulk fill not only creates a challenge for proper depth of cure and maximum physical properties on polymerisation, which will be addressed later in this article, but the large volume/amount of composite inserted, negatively affects the integrity of adhesion and increases microleakage. The typical access opening, which is essentially a very deep Class I cavity preparation, not only requires a large amount of composite, but as well, places the composite in the highest C-factor cavity preparation configuration of five. Only when utilising a composite deep in the prepared root canal, has the CFactor claimed to be higher at 200 to infinity.39 The suggested solution to the high polymerisation and contraction stress caused by bulk filling the access opening is to reduce the mass or bulk of composite by placing multiple Fiber Post Segments into the composite mass, before curing with the LED light. It has been conclusively shown that even when the C-Factor is at 200 or more in a prepared root

canal, minimizing the thickness of the composite (the mass), results in less contraction stress (S-Factor) which increases the patency of the bond to the root canal walls decreasing microleakage.40-43 Of course, the placement of inserts into composite is not a new idea. Glass ceramic inserts and beta quartz have been used to decrease composite volume and later silica glass and ceramics were introduced as a method for post-composite insertion bulk reduction.44-46 These techniques demonstrated increased marginal patency and less microleakage, but the inserts were difficult to contour and polish with adhesion between the inserts and the composite being a challenge.47,48 Composite megafillers were introduced later, as these were essentially the same as the matrix of the bulk filled composite, eliminating the inherent chemical differences between the materials.49,50 The authors suggest the insertion of multiple high quality, high capacity, light conducting fibre post segments (not all fibre posts conduct light efficiently51,52). This is not only to reduce the composite volume, thereby minimizing the potential for microleakage, but is also equally as critical to use the light conductance of the fibre post segments to significantly increase the degree of polymerization of the dual-cure composite resin cements/core materials deep in the access opening, thereby increasing their physical properties.53 In their review of polymerisation shrinkage, Cakir et al discuss the attenuation of light, which means that the deeper layers of composite resin are less cured with reduced mechanical properties, and that bulk filling shows significantly less hardness.54 Others have also shown that

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Fig. 5: Magnified view of the distal ridge of the second molar demonstrating a vertical crack.

Fig. 6: Completion of the debridement of the canals after rubber dam isolation with a better view of the extent of the distal crack line.

Fig. 7: The root canals have been obturated with gutta percha, a couple of mm below the level of the pulpal floor.

Fig. 8: After placement of the phosphoric acid (UltraEtch Ultradent) a microbrush is used to agitate the acid to clean the dentin, rinsed and lightly dried.

bulk placement and increased cavity depth result in a significant decrease in the effectiveness of polymerization, regardless of the exposure time.55 The ADA Professional Product review on Restorative Materials evaluated the depth of cure of 38 restoratives with ranges of 1.2 to 5mm. with a core material CompCoreAF syringMix Flow (W) being the lowest depth of cure at 1.2mm. Included in the study were measurements of maximum polymerisation shrinkage stress showing that LuxaCore Dual Smartmix W was the highest in stress MPa of the core materials tested, with Clearfil Photo Core (T) showing the highest development of shrinkage stress rate.56

Dual cure composite materials show the best physical properties and best polymerisation with sufficient light exposure, even though they are claimed to polymerise in the absence of light57-61 and ‘there is no evidence for a substantial chemically induced polymerisation of dual cure resins that occurs after light exposure is completed.’62 This reality is especially critical for dual-cure self-adhesive resin cements Maxcem and RelyX Unicem, which show a better degree of conversion when they are light activated, with a lack of light activation decreasing the monomer conversion by 25 to 40 per cent63 and even in their dual cure mode, the decree of cure at best among the self-etch adhesives is

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Fig. 9: MPa bonding agent is applied to a microbrush and agitated into the tubules, followed by evaporation of the solvent with an air-only line.

Fig. 10: The bonding agent is cured for 10 seconds with a Valo curing unit (Ultradent).

Fig. 11: Multiple MacroLock X-RO (Clinical Research Dental) fibre post segments (covered with a bonding agent which is first light cured) are verified for fit into the distal and two mesial canals.

Fig. 12: The Cosmecore A2 is injected into the bottom of the pulpal area filling to one half of the crown height, followed by the placement of the MacroLock X-RO segments at the canal orifices.

only 41.52 per cent.64-66 Thus, the placement of a bulk filled dual cure composite into the endodontic access opening, followed by the placement of multiple fibre post segments that carry sufficient light energy to the depth of the occlusal floor of the access preparation, will increase the polymerisation conversion, resulting in a composite that demonstrates superior physical properties.

As a final comment, it has been proven that immediate high intensity light polymerisation creates the greatest polymerisation stress. Ilie et al state that ‘fast contraction force development, high contraction stress and an early start of the

stress build up cause tension in the material with possible subsequent distortion of the bond to the tooth structure’.67 This finding has been collaborated by many others in the scientific literature with resultant recommendations for a soft start or lower energy over a longer period of time.68,69 Miller states that ‘manufacturers continue to make outlandish claims of their curing capabilities, most of which fall into the ‘too good to be true’ category’70 and Swift concludes that ‘the curing times recommended by a manufacturer might not deliver the amount of energy required to adequately cure composite, even under the ideal laboratory conditions’ that ‘very short

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Fig. 13: Occlusal view of the Cosmecore placed half way up the coronal tooth structure with the three segments placed. This first layer was light cured and followed with the completion of the final Cosmecore layer cured for 20 seconds.

Fig. 14: Post-operative radiograph of the completed restoration.

curing times are not a good idea in most clinical situations’ and that ‘longer curing times are required’.71 As well, Swift states that ‘instead of obtaining a boost, the “turbo” tip actually will reduce the amount of light reaching the composite to initiate the polymerisation process.’72

anticipated that after endodontic treatment, there would be enough coronal tooth structure left to allow for the preparation of a full coverage restoration with a fully circumferential ferrule of at least 2+mm in height, as well as width (Fig. 4). Figure 5 is a magnified view of the distal vertical crack, with the wear facet on the lingual cusp indicating a working side contact interference. Endodontic therapy was initiated under the microscope and after a thorough debridement and shaping of the root canal spaces (Fig. 6), the roots were obturated with gutta percha using a continuous wave of condensation technique to a level 2mm below the pulpal floor (Fig. 7). Phosphoric acid etching was initiated with the placement of Ultra-Etch Etchant (Ultradent) followed by microbrush agitation to work the etchant into the dentine, a thorough rinse, and light air drying (Fig. 8). Figure 9 shows the application of MPa bonding agent (Clinical Research Dental) with a microbrush, which again was followed by agitation to facilitate deeper penetration of the bonding agent, followed by evaporation of the solvent for ten seconds. The bonding agent was cured with a Valo Curing Light (Ultradent) for ten seconds utilising a Valo Proxiball Lens (Fig. 10). The Macro-Lock X-RO segments are verified for fit over the three canal orifices, and then coated with MPa bonding agent, which was cured for ten seconds (Fig. 11). Cosmecore (Cosmedent) A2 is injected into the pulp chamber one half way up the occlusal height of the clinical crown (Fig. 12). The Macro-Lock X-RO segments are

Clinical case A 64-year-old female presented to the endodontic office with an uneventful medical history. She complained of spontaneous pain on the lower left side of one week’s duration, which radiated up the ramus of the jaw and was causing headaches. She also complained of hot and cold sensitivity with pain on biting. Clinical tests revealed pain to cold, which lingered for five minutes and a sharp electric like pain when a tooth sleuth was placed over the DL cusp tip. A distal crack was visualised. There was no periodontal pocketing. All other mandibular left and maxillary left teeth tested vital and asymptomatic. The radiograph revealed a small shallow minimally invasive amalgam restoration (Fig. 3). The diagnosis was Cracked Tooth Syndrome with an irreversibly inflamed pulp. The patient was advised of the questionable long term prognosis with cracked teeth yet decided to try and retain it understanding that if the crack extends in the root proper and a periodontal pocket develops, then extraction with an implant replacement may be a viable solution.

Due to the minimal invasiveness of the restoration, it is

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References

Fig. 15: Occlusal view of the final restoration, trimmed and adjusted to the occlusion. The tooth is now ready for a full coverage crown or onlay to protect the clinical crack.

inserted into the Cosmecore followed by a 10 second cure with the Valo (Fig. 13). The rest of the occlusal access opening is filled with the Cosmecore and thoroughly cured with the Valo for 20 seconds. Figure 14 is the final postoperative radiograph showing the placement of the fibre segments into the core. The final restoration of the occlusal access opening is shown in Figure 15 after trimming and occlusal adjustment. The endodontically treated tooth is now ready for a final restoration.

This article has recommended restoring the teeth that meet the criteria for not needing the placement of fibre posts because of sufficient remaining tooth structure, with the use of multiple fibre post segments placed into the dual-cure composite cores of endodontically treated teeth based on the above evidence. This will decrease the overall polymerisation contraction and stress formation, thereby reducing occlusal microleakage, while at the same, time driving the dual-cure composite to a better overall cure or conversion for better physical properties.

The authors wish to thank Mrs. Laura Delellis for her work in creating the figures used in this article.

This article is reprinted with permission from Oral Health Dental Journal (May 2014).

Reprinted with permission by Roots 1/2015

1. Boksman L, Hepburn AB, Kogan E, Friedman M, de Rijk W. Solving post-endodontic root shape and taper variations with fiber post techniques. Oral Health November 20122;12-25 2. Boksman L, Santos GC, Friedman M. Post preparations: clinical solutions for long-term success. Dentistry Today January 2013;32(1):52-59 3. Da Silva NR, Raposo LHA, Versluis A, Fernando-Neto AJ, Soares CJ. The effect of post, core, crown type and ferrule presence on the biomechanical behaviour of endodontically treated bovine anterior teeth. J Posthet Dent. 2010;104:306-317 4. De Lima AF, Spazzin AO, Galafassi D, Correr-Sobrinho L, Carlini B Jr. Influence of ferrule preparation with or without glass fiber post on fracture resistance of endodontically treated teeth. J Appl Oral Sci 2009;18:360-363 5. Hu S, Osada T, Shimizu T, Warita K, Kawawa T. Resistance to cyclic fatigue and fracture of structur-ally compromised root restored with different post and core restorations. Dent Mater J 2005;24:225231 6. Jotkowitz A, Samet N. Rethinking the ferrule: a new approach to an old dilemma. BDJ 2010;209:25-33 7. Ferrari M, Vichi A, Gadda GM, Cagidiaco MC, Tay FR, Breschi L, Polimeni A, Goracci C. A randomized controlled trial of endodontically treated and restored premolars.

JDR. 2012;91(7):S72-S78 8. Boksman L, Glassman G, Santos GC, Friedman M. Fiber posts and tooth reinforcement: evidence in the literature. Oral Health May 2013 in press 9. Helig I. Endodontic failure caused by inadequate restorative procedures: Review and treatment recommendations. JPD 2002;87(6):674-678 10. Saunders WP, Saunders EM. Coronal leak-age as a cause of failure in root-canal therapy: a review. Endodontics and Dental Traumatology 1994;10(3):105-108 11. Sritharan A. Discuss that the coronal seal is more important than the apical seal for endodontic success. Aust. Endod. J. Dec 2002;28(3):112-115 12. Chong B. Coronal leakage and treatment failure. Journal of Endodontics 2006;21(3):159-160 13. Ferracane JL. Resin composite - state of the art. Dent Mat 2011;27(1):29-38 14. Maghaireh G, Bouschlicher MR, Qian F, Armstrong SR. The effect of Energy application sequence on the microtensile bond strength of different C-factor cavity preparations. Op Den 2007;32(2):124132 15. Tarle Z, Knezevid A, Demoli N, Meniga A, Sutalo J, Unterbrink G, Ristic M, Pichler G. Comparison of composite curing parameters: Effects of light source and curing mode on conversion, temperature rise and polymerization shrinkage. Op Dent. 2006;31(2)219-222 16. Asmussen E, Peutzfeldt A. Polymerization contraction of resin composite vs. energy and power density of light cure. European Journal of Oral Sciences Oct 2005;113(5):417-421 17. Dauvillier BS, Feilzer AJ, De Gee AJ, Davidson CL. Visco-elastic parameters of dental restorative materials during setting. JDR. 200;79(3):818-823 18. Feilzer AJ, De Gee AJ, Davidson CL. Setting stress in composite resin in relation to configuration of the restoration. JDR 1987;66(11):1636-1369 19. Sarrett DC. Clinical challenges and the relevance of materials testing for posterior composite restorations. Dent Mater 2005;(1):9-20

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20. Rueggeberg FA, Caughman WF, Curtis JW Jr. Effect of light intensity and exposure duration in cure of resin composite. Oper Dent 1994;19:26-32 21.

Lazarchik DA, Hammond BD, Sikes CL, Looney SW, Rueggeberg FA. Hardness comparison of bulk-filled/transtooth and incremental-filled/occlusally irradiated composite resins. J Prosthet Dent 2007;98(2):129-140 22. Peutzfeldt A. Resin composites in dentistry: the monomer systems. Eur J Oral Sci 1997;105:97-116 23.

Braga RR, Ferracane JL. Alternatives in polymerization contraction stress management.

24. Labella R, Lambrechts P, Van Meerbeek B, Vanherle G. Polymerization shrinkage and elasticity of flow-able composites and filled adhesives. Dent Mater 1999;15:128-137 25. Kinomoto Y, Torri M, Takeshige F, Ebisu S. Comparison of polymerization contraction stresses between self- and light-curing composites. J Dent 1999;27:383-389 26. Kleverlaan CJ, Feilzer AJ. Polymerization shrinkage and contraction stress of dental resin composites. Dent Mat 2005;21:1150-1157 27.

Goldman M. Polymerization shrinkage of resin-based restorative materials. Aus Dent J. June 1983;28(3):156-161

28. Cidreira Boaro LC, Goncalvas F, Guimaraes TC, Ferracane JL, Versluis A, Braga RR. Polymerization stress, shrinkage, and elastic modulus of current low-shrinkage restorative composites. Dent Mat Dec 2010;26(2):1144-1150 29. Rosin M, Urban AD, Gartner C, Bernhardt O, Splieth C, Meyer G. Polymerization shrinkage-strain and microleakage in dentinbordered cavities of chemically and light cured restorative materials.

Dent Mat Nov 2002;18(7):521-528 30. Irie M, Suzuki K, Watts DC. Marginal gap formation of lightactivated restorative materials: effects of immediate setting shrinkage and bond strength. Dent Mat 2002;18(3):203-210 31. Pensak T. Clinical Showcase — Get in the groove. JCDA Feb 2004;70(2):118-119 32. Davidson CL, De Gee AJ, Feilzer A. The competi-tion between the composite-dentin bond strength and the polymerization contraction stress. JDR 1984;63(12):1396-1399 33. Braga RR, Ballester RY, Ferracane JL. Factors involved in the development of polymerization shrink-age stress in resincomposites: a systematic review. Dent Mat. 2005;21:962-970 34. Unterbrink GL, Liebenberg WH. Flowable resin composites as “filled adhesives”: literature review and clinical recommendations.

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35. Yamazaki PCV, Bedran-Russo AKB, Pereira PNR, Swift EJ Jr. Microleakage evaluation of a new low-shrinkage composite restorative material. Op Dent Nov 2006;31(6):670-676 36. Braga RR, Boaro LCC, Kuroe T, Azevedo CLN, Singer JM. Influence of cavity dimensions on shrinkage stress development and microleakage of composite restorations. Dent Mat. Sept 2006;22(9):818-823 37. Campdonico CE, Tantbirojn DT, Olin PS, Versluis A. Cuspal deflection and depth of cure in resin-based composite restorations filled by using bulk, incremental and transtooth-illumination techniques. JADA Oct 2011;142(10)1176-1182 38. Watts DC, Satterthwaite JD. Axial shrinkage-stress depends upon both C-factor and composite mass. Dent Mat Jan 2008;24(1):1-8 39. Breschi L, Mazzoni A, De Stefano DE, Ferrari M. Adhesion to interadicular dentin: a review. J Adhes Sci Technol. 2009;23(78):1053-1083 40. Di Francescantonio M, Aquiar TR, Arrais CAG, Cavalcanti AN, Davanzo CU, Giannini M. Influence of viscosity and curing mode on degree of conversion of dual-cured resin cements. Eur J Dent Jan 2013;71(1):81-85 41. Tay FR, Loushine RJ, Lambrechts P, Weller RN, Pashley DH. Geometric factors affecting dentin bonding in root canals: a theoretical modeling approach. JOE Aug 2005;31(8):584-589 42. Okuma M, Nakjima M, Hosaka K, Ito S, Ikeda M, Foxton RM, Tagami J. Effect of composite post placement on bonding to root canal dentin using 1-step self-etch dual-cure adhesive with chemical activation mode. Dent Mat J. 2010;29(6):642-648 43. Egilmez F, Ergun G, Cekic-Nagas I, Vallittu PK, Lassila LVJ. Influence of cement thickness on the bond strength of tooth-colored post to root dentin after thermal cycling. Acta Odont Scan 2013;71:175-182 44. Ozcan M, Pfeffer P, Nergis I. Marginal adapta-tion of ceramic inserts after cementation. Op Dent 2002;27132-6 45. Bowen RL, George LA, Eichmiller FC, Misra DN. An esthetic glass-ceramic for use in composite restora-tion inserts. Dent Mat 1993;9:290-4 46.

Godder B, Zhukovsky L, Trushkowsky R, Epelbovm D. Microleakage reduction using glass ceramic inserts. Am J Dent 1994;7:74-6 47. Moazzami SM, Alaghehmand H. Effect of light con-ducting cylindrical inserts on gingival microleakage. J of Dent of Tehran University Medical Sciences 2007;4(1):32-36 48. George A, Richards ND, Eichmiller FC. Reduction of marginal gaps in composite restorations by use of glass-ceramic inserts. J Op Dent 1995;20:151-154 49. Gonczowksi K. Clinical evaluation of the composite fillings with the inserts. Dental Materials Poster Session III, The preliminary program for the IADR Pan European Federation 2006 (September 13-16,2006) iadr.confex.com 50. Bhushan S, Logani A, Shah N. Effect of pre-polymerized composite megafiller on the marginal adaptation of composite restorations in cavities with different C-factors: an SEM study. Indian Journal of Dental Research 2010;21(4):500-505 51. Goracci C, Corciolani G, Vichi A, Ferrari M. Light-transmitting ability of marketed fiber posts. JDr 2008;84(12):1122-1126 52. Ree M, Schwartz RS. The endo-restorative interface: current concepts. DCNA 2010;54:345-374

53. Taneja S, Kumari M, Gupta A. Evaluation of light transmission through different esthetic posts and its influence on the degree of polymerization of a dual cure resin cement. Journal of Conservative Dentistry Jan-Feb 2013;16(1):32-35 54. Cakir D, Sergent R, Burgess JO. Polymerization shrinkage — a clinical review. Inside Dentistry Sept 2007;84-87 55.

Yap AU. Effectiveness of polymerization in composite restoratives claiming bulk placement: effect of cavity depth and exposure time. Oper Dent Mar-Apr 2000;25(2):113-20 56. ADA Professional Product Review — Restorative materials.

Spring 2010;5(2)1-16 57. Peutzfeldt A. Dual cure resin cement. In vitro wear and effect of quality of remaining double bonds, filler volume, and light curing.

Acta Odont Scan 199553(1):29-34 58. El-Badrawy WA, El-Mowafy OM. Chemical ver-sus dual curing of resin inlay cements. JPD June 1995;73(6):515-524 59. Yan YL, Kim YK, Kim KH, Kwon TY. Changes in degree of conversion and microhardness of dental resin cements. Op Dent March 2010;35(2):203-210 60. Mendes LC, Matos IC, Miranda MS, Benzi MR. Dual-curing, self adhesive cement: influence of the polym-erization modes on the degree of conversion and micro-hardness. Mat Res. Apr/Jun 2010;13(2):171-176 61. Braga RR, Cesar PF, Gonzaga CC. Mechanical properties of resin cements with different activation modes. J of Oral Rehab March 2002;29(3):257-262 62. Rueggeberg FA, Caughman WF. The influence of light exposure on polymerization of dual cure resin cements. Op Dent 1993;18(2):48-55 63. Cadenaro M, Navarra CO, Antoniolli F, Mazzoni A, Di Lenarda R, Rueggeberg FA, Breschi L. The effect of curing mode on extent of polymerization and micro-hardness of dual-cured self-adhesive resin cements. Am J Dent 2010;23:14-18 64. Vrochari AD, Eliades G, Hellwig E, Wrbas KT. Curing efficiency of four self-etching, self adhesive resin cements. Dent Mat 2009;25:1104-1108 65. Moraes RR, Boscato N, Jardim PS, Schneider LFJ. Dual and Self-curing potential of self-adhesive resin cements as thin films. Op Dent Nov-Dec 2011;36(6):635-647 66. Agular TR, Francescantonio MD, Arrais CAG, Ambrosano GMB, Davanzo C, Giannini M. Influence of curing mode and time on degree of conversion of one conventional and two self adhesive resin cements. Op Dent May 2010;35(3):295-299 67. Ilie N, Felton K, Trixner K, Hickel R, Kunzelmann KH. Shrinkage behavior of a resin-based composite irradiated with modern curing units. Dent Mat May 2005;21(5):483-489 68. Feilzer AJ, Dooren LH, de Gee AJ, Davidson CL. Influence of light intensity on polymerization shrink-age and integrity of restorationcavity interface. Eur Journal of Oral Sciences 1995;103:322-326 69. Lu H, Stansbury JW, Bowman CN. Impact of curing protocol on conversion and shrinkage stress. JDR. Sept 2005;84(9):822-826 70. Miller MB. Curing lights: what you should know before buying one. Oral Health December 2009:48-56 71. Swift EJ Jr. Critical Appraisal Visible Light-Curing. JERD June 2011;23(3):191-196 72. Corciolani G, Vichi A, Swift EJ Jr. Contemporary Issues Turbo Tips. JERD 2011;23(5):294-295

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Smile analysis and photoshop smile design technique Edward A. McLaren,1 Lee Culp2

Introduction: Smile analysis and aesthetic design Dental facial aesthetics can be defined in three ways.

Traditionally, dental and facial aesthetics have been defined in terms of macro- and micro-elements. Macro-aesthetics encompasses the interrelationships between the face, lips, gingiva, and teeth and the perception that these relationships are pleasing. Microaesthetics involves the aesthetics of an individual tooth and the perception that the colour and form are pleasing.

Historically, accepted smile design concepts and smile parameters have helped to design aesthetic treatments. These specific measurements of form, colour, and tooth/aesthetic elements aid in transferring smile design information between the dentist, ceramist, and patient. Aesthetics in dentistry can encompass a broad area - known as the aesthetic zone.1 Rufenacht delineated smile analysis into facial aesthetics, dentofacial aesthetics, and dental aesthetics, encompassing the macro- and micro-elements described in the first definition above. 2 Further classification identifies five levels of aesthetics: facial, orofacial, oral, dentogingival, and dental (Table 1).1,3

Initiating smile analysis: Evaluating facial and orofacial aesthetics

Prof. Edward A. McLaren, DDS, is the director of the University of California, Los Angeles Center for Esthetic Dentistry in California, US. He maintains a private practice in Los Angeles.

1

Lee Culp, CDT, is an adjunct faculty member at the University of North Carolina at Chapel Hill School of Dentistry in the US and an accredited member of the American Academy of Cosmetic Dentistry. He practices in Dublin, California, and Raleigh, North Carolina.

The smile analysis/design process begins at the macro level, examining the patient’s face first, progressing to an evaluation of the individual teeth, and finally moving to material selection considerations. Multiple photographic views (e.g., facial and sagittal) facilitate this analysis.

At the macro level, facial elements are evaluated for form and balance, with an emphasis on how they may be affected by dental treatment.3,4 During the macroanalysis, the balance of the facial thirds is examined (Fig. 1). If something appears unbalanced in any one of those zones, the face and/or smile will appear unaesthetic.

Such evaluations help determine the extent and type of treatment necessary to affect

2

Figure 1: Three altered views of the same patient enable analysis of what can be accomplished to enhance facial and smile aesthetics.

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Table 1: Components of smile analysis and aesthetic design Facial aesthetics

Total facial form and balance

Orofacial aesthetics

Maxillomandibular relationship to the face and the dental midline relationship to the face pertaining to the teeth, mouth and gingiva

Oral aesthetics

Labial, dental, gingival; the relationships of the lips to the arches, gingiva, and teeth

Dentogingival aesthetics

Relationship of the gingiva to the teeth collectively and individually

Dental aesthetics

Macro- and micro-aesthetics, both inter- and intra-tooth

Figure 2: Sagittal views best demonstrate which specialists should be involved in treatment, whether orthodontists or maxillofacial surgeons, to best aesthetically alter the facial aesthetics.

the aesthetic changes desired. Depending on the complexity and uniqueness of a given case, orthodontics could be considered when restorative treatment alone would not produce the desired results (Fig. 2), such as when facial height is an issue and the lower third is affected. In other cases - but not all - restorative treatment could alter the vertical dimension of occlusion to open the bite and enhance aesthetics when a patient presents with relatively even facial thirds (Fig. 3).

Evaluating oral aesthetics The dentolabial gingival relationship, which is considered oral aesthetics, has traditionally been the starting point for treatment planning. This process begins by determining the ideal maxillary incisal edge placement (Fig. 4). This is accomplished by understanding the incisal edge position relative to several different landmarks. The following questions can be used to determine the ideal incisal edge position: • Where in the face should the maxillary incisal edges be placed?

• What is the proper tooth display, both statically and dynamically?

• What is the proper intra- and inter- tooth relationship (e.g., length and size of teeth, arch form)?

• Can the ideal position be achieved with restorative dentistry alone, or is orthodontics needed?

Figure 3: Drawing a line along the glabella, subnasale, and pogonion enables a quick evaluation of aesthetics without the need for radiographs to determine alignment of ideal facial elements.

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5 Figure 4: Evaluating the maxillary incisal edge position is the starting point for establishing oral aesthetics.

Figure 5: According to the 4.2.2 rule, this patient’s smile is deficient in aesthetic elements, having only 1 mm of tooth display at rest (left), minus 3 mm of gingival display, and 4 mm of space between the incisal edge and the lower lip (right).

6

7 Figure 6: Gingival symmetry in relation to the central incisors, lateral incisors and canines is essential to aesthetics. Optimal aesthetics is achieved when the gingival line is relatively horizontal and symmetrical on both sides of the midline in relation to the central incisors and lateral incisors.

Figure 7: The aesthetic ideal from the gingival scallop to the tip of the papilla is 4–5 mm.

In order to facilitate smile evaluation based on these landmarks, the rule of 4.2.2 - which refers to the amount of maxillary central display when the lips are at rest, the amount of gingival tissue revealed, and the proximity of the incisal line to the lower lip - is helpful (Fig. 5). At a time when patients perceive fuller and brighter smiles as most aesthetic, 4mm of maxillary central incisor display while the lips are at rest may be ideal.2,5 In an aesthetic smile, seeing no more than 2mm of gingiva when the patient is fully smiling is ideal.6 Finally, the incisal line should come very close to and almost touch the lower lip, being no more than 2mm away.2 These guidelines are somewhat subjective and should be used as a starting point for determining proper incisal edge position.

Dentogingival aesthetics Gingival margin placement and the scalloped shape, in particular, are well discussed in the literature. As gingival heights are measured, heights relative to the central incisor, lateral incisor, and canine in an up/down/up relationship are considered aesthetic (Fig. 6). However, this may create a false perception that the lateral gingival line is incisal to

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Figure 8-10: Acceptable width-to-length ratios fall between 70 % and 85 %, with the ideal range between 80 % and 85 %.

the central incisor. Rather, in most aesthetic tooth relationships, the gingival line of the four incisors is approximately the same line (Fig. 6), with the lateral incisor perhaps being slightly incisal.7 The gingival line should be relatively parallel to the horizon for the central incisors and the lateral incisors and symmetric on each side of the midline.2,8 The gingival contours (i.e., gingival scallop) should follow a radiating arch similar to the incisal line. The gingival scallop shapes the teeth and should be between 4mm and 5mm (Fig. 7).9 Related to normal gingival form is midline placement.

Although usually the first issue addressed in smile design, it

is not as significant as tooth form, gingival form, tooth shape, or smile line.

Several rules can be applied when considering modifying the midline to create an aesthetic smile design: • The midline only should be moved to establish an aesthetic intra- and inter-tooth relationship, with the two central incisors being most important.

• The midline only should be moved restoratively up to the root of the adjacent tooth. If the midline is within 4mm of the centre of the face, it will be aesthetically pleasing.

• The midline should be vertical when the head is in the postural rest position.

11

12

13

14

Figure 11: An acceptable starting point for central incisors is 11mm in length, with lateral incisors 1–2mm shorter than the central incisors, and canines 0.5–1mm shorter than the central incisors for an aesthetic smile display. Figure 12: The canines and other teeth distally located are visually perceived as occupying less space in an aesthetically pleasing smile. Figure 13: A general rule for achieving proportionate smile design is that lateral incisors should measure two-thirds of the central incisors and canines four-fifths of the lateral incisors. Figure 14: If feasible, the contact areas can be restoratively moved up to the root of the adjacent tooth.

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Figure 15: Photoshop provides an effective and inexpensive way to design a digital smile with proper patient input. To start creating custom tooth grids, open an image of an attractive smile in Photoshop and create a separate transparent layer. Figure 16: The polygonal lasso tool is an effective way to select the teeth. Figure 17: Click “edit > stroke,” then use a two-pixel stroke line (with colour set to black) to trace your selection. Make sure the transparent layer is the active working layer. Figure 18: Image of the central incisor with a two-pixel black stroke (tracing). Figure 19: Image of the teeth traced up to the second premolar to create a tooth grid. Figure 20: Size the image in Photoshop.

Figure 21: Save the grid as a .png or .psd file type and name it appropriately. Create other dimension grids using the same technique. Figure 22: To determine the digital tooth size, a conversion factor is created by dividing the proposed length by the existing length of the tooth.

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Figure 23: Select the ruler tool in Photoshop. Figure 24: Measure the digital length of the central incisor using the ruler tool. Figure 25: Measure the new digital length using the conversion factor created earlier. Figure 26: Create a new transparent layer and mark the new proposed length with the pencil tool.

Evaluating dental aesthetics Part of evaluating dental aesthetics for smile design is choosing tooth shapes for patients based on their facial characteristics (e.g., long and dolichocephalic, or squarish and brachycephalic). When patients present with a longer face, a more rectangular tooth within the aesthetic range is appropriate. For someone with a square face, a tooth with an 80% width-to-length ratio would be more appropriate.

The width-to-length ratio most often discussed in the literature is between 75% and 80%, but aesthetic smiles could demonstrate ratios between 70% and 75% or between 80% and 85% (Figs. 8–10).1 The length of teeth also affects aesthetics. Maxillary central incisors average between 10mm and 11mm in length.

According to Magne, the average length of an unworn maxillary central to the cementoenamel junction is slightly

over 11mm.10 The aesthetic zone for central incisor length, according to the authors, is between 10.5mm and 12mm, with 11mm being a good starting point. Lateral incisors are between 1mm and a maximum of 2mm shorter than the central incisors, with the canines slightly shorter than the central incisors by between 0.5mm and 1mm (Fig. 11).

The inter-tooth relationship, or arch form, involves the golden proportion and position of tooth width.

Although it is a good beginning, it does not reflect natural tooth proportions. Natural portions demonstrate a lateral incisor between 60% and 70% of the width of the central incisor, and this is larger than the golden proportion.11 However, a rule guiding proportions is that the canine and all teeth distal should be perceived to occupy less visual space (Fig. 12). Another rule to help maintain proportions throughout the arch is 1-2-34-5; the lateral incisor is two-thirds of the central incisor and

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28

29

30

Figure 27: Open the image of the chosen tooth grid in Photoshop and drag the grid on to the image of teeth to be smile designed.

This will create a new layer in the image to be smile designed. Figure 28: Adjust the grid as required while maintaining proper proportions by using the free transform tool from the edit menu. Figure 29: Modify the grid shape as necessary using the liquify tool.

Figure 30: Select all of the teeth in the grid by activating the magic wand selection tool and then clicking on each tooth with the grid layer activated (highlighted) in the layers palette.

the canine is four-fifths of the lateral incisor, with some latitude within those spaces (Fig. 13). Finally, contact areas can be moved restoratively up to the root of the adjacent tooth.

Beyond that, orthodontics is required (Fig. 14).

Creating a digital smile designed in Photoshop Although there are digital smile design services available to dentists for a fee, it is possible to use Photoshop CS5 software (Adobe Systems) to create and demonstrate for patients the proposed smile design treatments. It starts by creating tooth grids—predesigned tooth templates in different width-to-length ratios (e.g., 75% central, 80% central) that can be incorporated into a custom smile design based on patient characteristics. You can create as many different tooth grids as you like with different tooth proportions in the aesthetic zone. Once completed, you will not have to do this step again, since you will save the created tooth grids and use them to create a new desired outline form for the desired teeth.

Follow these recommended steps: • To begin creating a tooth grid, use a cheek-retracted image of an attractive smile as a basis (e.g., one with a 75% width-to-length ratio). Open the image in Photoshop and create a new clear transparent layer on top of the teeth (Fig. 15). This transparent layer will enable the image to be outlined without the work being embedded into the image.

• Name the layer appropriately and, when prompted to identify your choice of fill, choose “no fill,” since the layer will be transparent, except for the tracing of the tooth grid.

• To begin tracing the tooth grid, activate a selection tool, move to the tool palette, and select either the polygonal lasso tool or the magnetic lasso tool. In the authors’ opinion, the polygonal works best. Once activated, zoom in (Fig. 16) and trace the teeth with the lasso tool.

• To create a pencil outline of the tooth, with the transparent layer active, click on the edit menu in the menu bar; in the edit drop-down menu, select “stroke”; choose black

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32

33

34

Figure 31: Use the selection modify tool to expand the selection to better fit the grid shape. Figure 32: Activate the layer of the teeth by clicking on it. Blue-coloured layers are active. Figure 33: With the layer of the teeth highlighted, choose “liquify”; a new window will appear with a red background called a “mask”. Figure 34: Shape one tooth at a time as needed by selecting “wand”.

for colour, and select a two-pixel stroke pencil line (Fig. 17), which will create a perfect tracing of your selection.

Click “OK” to stroke the selection. Select (trace with the lasso selection tool) one tooth at a time and then stroke it (Fig. 18). Select and stroke (trace) the teeth up to the second premolar (the first molar is acceptable; Fig. 19).

• The image should be sized now for easy future use in a smile design. In the authors’ experience, it is best to adjust the size of the image to a height of 720 pixels (Fig. 20) by opening up the image size menu and selecting 720 pixels for the height. The width will adjust proportionately.

• At this time, the tooth grid tracing can be saved, without the image of the teeth, by double-clicking on the layer of the tooth image. A dialog box reading “new layer” will appear; click “OK.” This process unlocks the layer of the teeth so it can be removed. Drag the layer of the teeth to the trash, leaving only the layer with the tracing of the teeth (Fig. 21). In the file menu, click “save as” and choose “.png” or “.psd” (Photoshop) as the file type. This will preserve the transparency. You do not want to save it as a JPEG, since this would create a white background

around the tracing. Name the file appropriately (e.g., 75% W/L central).

• By tracing several patients’ teeth that have tooth size and proportion in the aesthetic zone and saving them, you can create a library of tooth grids to custom design new teeth for your patients who require smile designs.

Figure 35: Once all of the teeth have been shaped, use the liquify tool.

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Figure 36: Tooth brightness is adjusted using commands from the dodge tool menu or image adjustments menu. Figure 37: Image of all the teeth whitened with the dodge tool.

The Photoshop smile design technique The Photoshop Smile Design (PSD) technique can be done on any image, and images can be combined to show the full face or the lower third with lips on or lips off. This article demonstrates how to perform the technique on the cheekretracted view.

The first step in the PSD technique is to create a digital conversion of the actual tooth length and width, and then digitally determine the proposed new length and proportion of the teeth.

Determining digital tooth size

To determine digital tooth size, follow these steps: • Create a conversion factor by dividing the proposed length (developed from the smile analysis) by the existing length of the tooth.

• The patient’s tooth can be measured in the mouth or on the cast (Fig. 22). If the length measures 8.5mm but needs to be at 11 mm for an aesthetic smile, divide 11 by 8.5.

The conversion factor equals 1.29, a 29% digital increase lengthwise.

• Open the full-arch cheek-retracted view in Photoshop, and zoom in on the central incisor.

• Select the eyedropper palette. A new menu will appear.

Select the ruler tool (Fig. 23).

• Click and drag the ruler tool from the top to the bottom of the tooth to generate a vertical number, in this case 170 pixels (Fig. 24). Multiply the number of pixels by the conversion factor. In this case, 170 x 1.29 = 219 pixels; 219 pixels is digitally equivalent to 11 mm (Fig. 25).

Determine the digital tooth width using the same formula.

• Create a new layer, leave it transparent, and mark the measurement with the pencil tool (Fig. 26).

Applying a new proposed tooth form Next, follow these steps: • After performing the smile analysis and digital measurements, choose a custom tooth grid appropriate for the patient. Select a tooth grid based on the width-tolength ratio of the planned teeth (e.g., 80/70/90 or 80/65/80). Open the image of the chosen tooth grid in Photoshop and drag the grid on to the image of teeth to be smile designed (Fig. 27).

• If the shape or length is deemed inappropriate, press the command button (control button for PCs) and “z” to delete and select a suitable choice.

• Depending on the original image size, the tooth grid may be proportionally too big or too small. To enlarge or shrink the tooth grid created (with the layer activated), press command (or control) and “t” to bring up the free transform function. While holding the shift key (holding the shift key allows you to transform the object proportionally), click and drag a corner left or right to expand or contract the custom tooth grid.

• Adjust the size of the grid so that the outlines of the central incisors have the new proposed length. Move the grid as necessary using the move tool so that the incisal edge of the tooth grid lines up with the new proposed length (Fig. 28).

• Areas of the grid can be individually altered using the liquify tool (Fig. 29).

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Digitally creating new aesthetic teeth Next, follow these suggested steps: • With the new tooth grid layer and the magic wand tool both activated, click on each tooth to select all of the teeth in the grid (Fig. 30).

• Expand the selection by two pixels in the expand menu; click “select > modify > expand” (Fig. 31). Note that the selection better approximates the grid. You can expand the selection or contract as necessary using the same menu.

• Activate the layer of the teeth (cheek-retracted view) by clicking on it (Fig. 32).

• Next, activate the liquify filter (you will see a red mask around the shapes of the proposed teeth). The mask creates a digital limit that the teeth cannot be altered beyond. This is similar to creating a mask with tape for painting a shape (Fig. 33).

• Use the forward warp tool by clicking on an area of the existing tooth and dragging to mold/shape the tooth into the shape of the new proposed outline form (Fig. 34).

Repeat this for each tooth. If you make a mistake or do not like something, click command (or control) and “z” to go back to the previous edit (Fig. 35).

allows the patient to compare the new smile design to his/her original teeth before agreeing to treatment.

Create a copy To save the information you have created for presentation to the patient, follow these tips: • Go to “file” and select “save as.”

• When the menu appears, click on the “copy” box.

• Name the file at that step.

• Save it as a JPEG file type.

• Designate where you want it saved.

• Click “save.”

A file of the current state of the image will be created in the designated area. You can now continue working on the image and save again at any point you want.

Conclusion Knowledge of smile design, coupled with new and innovative dental technologies, allows dentists to diagnose, plan, create, and deliver aesthetically pleasing new smiles.

Simultaneously, digital dentistry is enabling dentists to provide what patients demand: quick, comfortable, and predictable dental restorations that satisfy their aesthetic needs.

Adjusting tooth brightness The following steps are recommended next: • Select the whitening tool (dodge tool) to brighten the teeth.

In the dodge tool palate, click on “midtones” and set the exposure to approximately 20%. Click on the areas of the tooth you want brightened (Figs. 36 & 37).

• Alternatively, with the teeth selected, you can use the brightness adjustment in the brightness/contrast menu; click “image > adjustments > brightness/ contrast”.

Performing the changes on only one side of the mouth

Editorial note: A complete list of references is available from the publisher.

This article was originally published in the Journal of Cosmetic Dentistry, spring issue, No 1/2013, Vol. 29, and the Clinical Masters Magazine No 1/2015.

Reprinted with permission by Cad/Cam, 2/2015

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Achieving predictable outcomes of mandibular reconstruction with virtual treatment planning Nika Vafaei,1 Carlo Ferretti2

Nika Vafaei BDS (WITS), MDent (MFOS), FCMFOS(SA) Sandton Intercare Day Hospital

1

One of the main goals of reconstruction of mandibular defects is to restore mandibular continuity and morphology to allow functional rehabilitation with osseo-integrated dental implants. This is a challenge if significant distortion of the normal anatomy has occurred due to the aggressive nature and extensive growth of the various pathologies involving the mandible. Various options are available for mandibular reconstruction, but autologous grafts remain the gold standard in various forms.1, 2 Whilst free flap reconstruction allows for immediate reconstruction, the particulate cortico-cancellous bone (PCCB) graft allows for a far more accurate restitution of mandibular morphology and facial aesthetics (with decreased cost and morbidity), as it permits for more accurate dental rehabilitation.3-9 A challenge for reconstructive surgeons has been reconstituting the mandibular arch as this has implications for facial form and dental arch replication. The use of virtual treatment planning improves the predictability of reconstructive goals. A protocol refined over several years, exploiting virtual treatment planning when appropriate, has optimized treatment outcomes and is reviewed by presenting the treatment sequence for a typical case.

Following clinical examination, planning for resection and intermediate reconstruction requires a computed tomography (CT) scan. The slice data is saved in Digital Imaging Communication in Medicine (DICOM) format and imported into Mimics Software (Materialise, Leuven, Belgium). The CT scan is then viewable as a 3D image to allow for virtual resection, which gives detailed information regarding the extent of the lesion to plan the resection and ensure pathology free margins (Figure 1). The three dimensional images are imported into 3-Matic software (Materialise,

Carlo Ferretti1, 2, 3 BDS (WITS), MDent (MFOS), FCD(SA)MFOS Sandton Intercare Day Hospital Bedford Gardens Clinic Department of Maxillofacial and Oral Surgery at the University of the Witwatersrand, Johannesburg

2

Corresponding author: Dr. Nika Vafaei Tel: (011) 783 7488 Fax: (011) 783 7625 Email: drnikav@gmail.com

Figure 1: Reformatted 3D CT Scan of a mandibular tumour.

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Figure 2: Undistorted virtual mandible.

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3

4

5

Figure 3: 3D printed model.

Figure 4: Patient matched titanium reconstruction plate with condyle/ramus spacer.

Figure 5: Mandibular resection specimen.

Belgium) to create a virtual mandible unaffected by distortion (Figure 2). A model of the ideal mandible is prepared with zp 131 powder silica, plaster composite on a Z Corp 510 3d inkjet printer (Z-Corp, Burlington, Massachusetts) (Figure 3). 10 Using the model, a 2.4mm titanium reconstruction plate is adapted directly on the printed model (Figure 4). The tumor is resected (Figure 5) and with the aid of measurements and markings obtained from the 3D model and virtual planning, the reconstruction plate is secured to the extant mandible.

Once the plate is secured, a silicon spacer is secured to the plate with wires. The spacer sculpts the healing of the soft

6a

tissues to form a recipient bed into which the bone graft will be placed 8 weeks later (Figure 6a & b). After securing the spacer, the inter-maxillary fixation is released to ensure the correct aesthetic positioning of the plate. Thereafter, the soft tissues are closed in layers, starting with the appropriate reattachment of the suprahyoid and supraglottic musculature. The patient is then placed into inter-maxillary fixation for the post-operative period of 6 weeks. Postoperatively the patient is monitored in the Intensive Care Unit for the initial 24 hours. All medication is administered intravenously and all feeding is via nasogastric tube for the first 7 days post-surgery.

6b

Figure 6: (a) Spacer secured via intraoral approach, (b) via extraoral approach to titanium reconstruction plate.

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7b

Figure 7: (a) Particulated cortico-cancellous bone graft, (b) compressed into syringes.

Figure 8: Recipient soft tissue bed after spacer removal.

Figure 9: Compressed bone graft packed into recipient soft tissue bed.

After eight weeks, definitive reconstruction is effected with a posterior iliac crest graft (bilateral or unilateral depending on defect size), as a large volume of cortico-cancellous bone is required to adequately reconstruct the mandible (Figure 7a). The bone is milled and packed into 20ml syringes and maximally compressed to ensure a compact bone graft (Figure 7b). The spacer is exposed via an extraoral approach. If healing has been uneventful, a smooth recipient bed (Figure 8) will have formed for the placement of the particulate bone graft (Figure 9). The malleable nature of the PCCB graft and its implantation into

a recipient bed sculpted by a spacer allows duplication of mandibular arch form (Figure 10).9 Once grafting is complete, layered tension-free closure of the soft tissues is carried out around the plate and grafted bone. The patient is then placed into inter-maxillary fixation to allow for stability of the graft and soft tissues to heal uneventfully.

Post-operative care is the same as the first surgery, i.e. patient is monitored in ICU for the initial 24 hours, followed by another 6 days in hospital with continued monitoring ensuring operative sites healing well. Patients are reviewed weekly until inter-maxillary fixation released at 6 weeks.

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Figure 10: Diagnostic wax up indicators (arrows) seen on occlusal X-ray for implant planning. Good restitution of arch form and trabecular pattern.

Figure 11: Panoramic radiograph 6 months post grafting showing loss of mandible/graft interface, restitution of alveolar height and trabecular morphology.

Six months later, planning is initiated for the dental rehabilitation of the grafted patients. Graft maturation is confirmed with panoramic radiography, once the graft/mandible interface is not visible and normal trabecular pattern has been established (Figure 10 & 11).

Planning for implant placement follows the standard approach for guided implant placement. A diagnostic wax up is prepared as an aid to scan template manufacture. The patient has a CT scan of the trial prosthesis in position to facilitate appropriate virtual implant placement. Treatment planning can be done with one of several proprietary software packages (Figure 12).

Based on the treatment planning a surgical guide is manufactured (Figure 13a) and used to place the implants (Figure 13b). Impressions are taken in theatre for the construction of a sulcus conformer. Healing abutments are

12

then placed and the mucoperiosteum sutured closed.

Three months post placement a sulcoplasty is performed and sulcus molding is aided by a conformer (Figure 14a & b) secured to the implants. Once secondary mucosalization is complete definitive prosthesis is manufactured (Figure 15a, b & 16).

The impact of loss of mandibular continuity on a patient's quality of life is substantial. Resolving the multiple problems associated with the loss of this complex organ is essential to return patients to pre-morbid function and appearance. The protocol reviewed here has been refined over several years and has been used to treat over 60 patients. The addition of digital technology coupled with a sound understanding of the biology of bone grafting ensure repeatable and predictable outcomes for patients with devastating surgical injuries.

13a

13b

Figure 12: Virtual treatment planning of implant positioning and surgical guide.

Figure 13: (a) Surgical guide in position, (b) placement of implants in grafted mandible. Bone graft is well consolidated with a prominent cortical layer.

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14b

Figure 14: Sulcus conformer in situ following sulcoplasty surgery.

15a

15b

Figure 15: (a) Frontal and (b) occlusal view of final prosthesis in situ. Prosthesis height fulfills the criteria for good implant/crown ratio. Position of access holes confirm ideal implant position.

Acknowledgement We would like to thank Carol Spence from Precise Bone Smart Technology for assistance with digital simulation.

Doctors Dale Howes, Emil Cahi and Selwyn Kabrun for outstanding prosthodontic support and collaboration.

References 1. Habal MB, Reddi, H. Bone grafts & bone substitutes.

W. B. Saunders Comp. Harcourt Brace Jovanovich, Inc. Pennsylvania 19106. 1992 pg: 18-134.

2. Ferretti C, Ripamonti U. Human segmental mandibular defects treated with naturally derived bone morphogenetic proteins. J Craniofac Surg. 2002 vol. 13:434-44.

3. Boyne PJ, Zarem H. Osseous reconstruction of the resected mandible. Am J Surg. 1976 Jul; 132(1):49-53.

4. Dumbach J, Rodemer H, Spitzer WJ, Steinhäuser EW. Mandibular reconstruction with cancellous bone, hydroxylapatite and titanium mesh. J Craniomaxillofac Surg.

1994 Jun;22(3):151-5 5. Marx RE. Mandibular reconstruction. J Oral Maxillofac Surg. 1993 May;51(5):466-79

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Figure 16: Panoramic radiograph of final prosthesis in situ.

6. Tideman H, Samman N, Cheung LK. Functional reconstruction of the mandible: a modified titanium mesh system. Int J Oral Maxillofac Surg. 1998 Oct; 27(5):339-45.

7. Iino M, Fukuda M, Nagai H, Hamada Y, Yamada H, Nakaoka K, Mori Y, Chikazu D, Saijo H, Seto I, Ohkubo K, Takato T. Evaluation of 15 mandibular reconstructions with Dumbach Titan Mesh-System and particulate cancellous bone and marrow harvested from bilateral posterior ilia. Oral Surg Oral Med Oral Pathol Oral RadiolEndod. 2009 Apr;107(4) :e1-8 8. Simon EN, Merkx MA, Kalyanyama BM, Shubi FM, Stoelinga PJ. Immediate reconstruction of the mandible after

resection for aggressive odontogenic tumours: a cohort study Int J Oral Maxillofac Surg. 2013 Jan; 42(1):106-12.

9. Ferretti C, Rikhotso E, Muthray E, Reyneke J, Ripamonti U. Reconstruction of 56 mandibular defects with autologous compressed particulate cortico-cancellous bone graft. In press Br J Oral Maxillofac.

10. Ferretti C, Rikhotso E, Muthray E, Reyneke J. Interim reconstruction and space maintenance of mandibular continuity defects preceding definitive osseous reconstruction. Br J Oral Maxillofac Surg. 2013 Jun;51(4):319-25. doi: 10.1016/j.bjoms.2012.06.012.

Epub 2012 Jul 19.

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Making sense of mouth ulceration: part nine Crispian Scully1 The clinical appearance of an oral ulcer on its own is rarely diagnostic. Any single ulcer lasting more than three weeks must be regarded with suspicion.

Some systematic way of dealing with ulceration is needed, such as my system of splitting causes into: • Systemic • Malignancy • Local • Aphthae • Drugs.

This article focuses on oral malignancy – this is mainly cancer.

Oral cancer Mouth cancer is the largest group of head and neck cancers and is mainly oral squamous cell carcinoma (OSCC).

Most cases (90%) are in people over the age of 45 and it is more common in men than women. However, the gender gap is narrowing over time and OSCC is increasing in younger patients (there’s been a 25% increase in patients under the age of 45 over last 20 years). Now, one in 10 cases are diagnosed in people under the age of 50.

In the UK, incidence rates are highest in Scotland; rates are also high among South Asian women and in recent/new migrants from the eastern EU. Risk factors for OSCC include lifestyle factors mainly. Most of these are addictive, affect other body systems, cause other health problems, often are multiple habits and have spread by migration.

These risk factors include use of tobacco, alcohol, betel and khat.

Tobacco • A 20-fold risk of OSCC with heavy smokers • Strong dose-response relationship • Dark tobacco worst • Cancers of larynx, pharynx, lung, oesophagus, stomach, colon, liver, breast also associated • Other diseases are related to tobacco.

Professor Crispian Scully CBE FMedSci DSc FDS MD is professor emeritus at UCL, London, King James IV professor at the Royal College of Surgeons, Edinburgh, Harley Street Diagnostic Centre, 16 Devonshire Street and 19 Wimpole Street, London.

1

Alcohol • A 20-fold risk of OSCC with heavy drinkers • Strong dose-response relationship • Spirits worst • Cancers of stomach, colon, liver, breast associated • Other diseases associated with alcohol use • A 50-fold risk of OSCC for heavy smoking and drinking.

Betel Betel contains stimulant arecoline and may cause: • Cancer: oral, oesophageal, pancreatic, hepatocellular • Oral submucous fibrosis • Adverse birth outcomes • Chronic kidney disease • Contact dermatitis • Liver cirrhosis

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• Hypertension • Metabolic syndrome.

Khat (Catha edulis) Khat contains stimulant cathinone.

Other factors Certain occupations may also increase the risk of OSCC, such as those with exposure to benzene, fossil fuel or pesticide (see Table 1).

Microbial mutagens associated with OSCC include: • Candidiasis • Syphilis • Oral organisms in poor oral hygiene • Human papillomaviruses (HPV).

HPV is associated mainly with oropharyngeal carcinoma (OPSCC). Risk factors for oropharyngeal cancer include a high lifetime number of oral sex partners (six or more) or vaginal sex partners (26 or more).

The main causal agent is HPV-16 (90%), but also HPVs 18, 31, 33. HPV-associated cancers are increasing in the USA, Canada, Australia, and several European countries, including Denmark and Sweden.

Now, 70% of OPSCC is caused by HPV. It has been estimated that OPSCCs will exceed cervical cancer by 2020. Fortunately, new oral oncogenic HPV infections are rare and mostly cleared by the host within one year. The new HPV vaccines also have a protective effect.

Other possible risk factors for OSCC include: • Diseases: – Diabetes – Discoid lupus erythematosus – Dyskeratosis congenita – Fanconi anaemia – Plummer-Vinson syndrome – Scleroderma – Xeroderma pigmentosum • Defects in immunity: – Chronic candidiasis – HIV/AIDS – Li-Fraumeni syndrome • DXR (radiotherapy) • Drugs: – Antihypertensives – Immunosuppressives – Marijuana – Mate.

Figure 1: The lateral border of the tongue is a common site for OSCC

There appear to be two distinct pathways to cancer in the mouth: 1. Most lesions (around 75%) are related to use of tobacco or alcohol 2. Some, especially at the back of the mouth in the oropharynx, are related to exposure to human papillomavirus (HPV).

For lip OSCC, high exposure to sunlight UV radiation is implicated.

Aetiological factors for OSCC may thus be summarised to include: • Smoking • Spirits • Spices • Sepsis • Sex • Sunlight.

Clinical features of OSCC The common site for OSCC is the lateral border of tongue (Figure 1), but cancers can arise anywhere.

Table 1: occupations with an increased risk of OSCC • • • • • • • • •

Blacksmithing Building industry Carpet installation Construction work Driving Electricity working Furniture industry Grain production Machinery operations

• Masonry • Metal working • Painting • Petroleum industry • Plumbing • Railway working • Textile industry • Woodworking.

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OSCC is persistent, with variable pain. RULE is an acronym that focuses on single lesions that persist for three or more weeks, including: • Red and/or white • Ulcer • Lump • Especially combinations of the above, or if indurated (firm on palpation) should be regarded with suspicion, and biopsy arranged (Scully, 2013).

Other features may be: • Pain • Paraesthesia • Anaesthesia • Bone destruction • Tooth mobility • Pathological fracture • Dysarthria • Dysphagia.

Metastasis is initially to cervical lymph nodes, later to liver, bones and brain.

Table 2: reducing the risk of developing mouth cancer

Early diagnosis

Elsevier Churchill Livingstone (Edinburgh and London). ISBN 13: 29780443100376 Scully C, Almeida ODP, Bagan J, Diz PD, Mosqueda A (2010) Oral medicine and pathology at a glance. Wiley-Blackwell (Oxford) ISBN 978-1-4051-9985-8 Scully C, Flint S, Bagan JV, Porter SR, Moos K (2010) Oral and maxillofacial diseases. Informa Healthcare (London and New York).

ISBN-13: 9780415414944 Scully C, Bagan JV, Carrozzo M, Flaitz C, Gandolfo S (2012) Pocketbook of oral disease. Elsevier, London. ISBN 978-0-70204649-0 Scully C (2013) Oral and maxillofacial medicine. 3rd edition.

Churchill Livingstone (Edinburgh). ISBN 9780702049484 Scully C (2012) Aide memoires in oral diagnosis: mnemonics and acronyms (the Scully system). Journal of Investigative and Clinical Dentistry 3(4): 262-3 Scully C (2013) RULE for cancer diagnosis. British Dental Journal 215: 265-6

Patients’ quality of life during and after treatment has steadily improved but survival rates have barely increased. The stage at which mouth cancer is diagnosed has a significant effect on overall survival. Early diagnosis reduces: • Mortality • Morbidity • Disfigurement • Poor quality of life • Treatment duration • Costs.

Referral is usually indicated. Delays in referral from primary to secondary care are associated with a three-fold increase in mortality. Delays in diagnosis can lead to patients having more advanced stages of cancer, especially when delay is more than a month.

The stage at which cancer is diagnosed has a significant effect on overall survival and quality of life. Localised cancer (confined to a primary site) and small (stage one: less than 2cm), has approximately 90% two-year survival rate but most cancers are found at late stage, larger than 2cm (60% present with late stage – stages three and four – disease, when survival is about half as good).

Late stage diagnosis is not because oral cancer is hard to discover but mainly because of a lack of patient awareness related to: • Socio-economic status/education • Cognitive function.

Opportunistic screenings would yield early discovery by healthcare professionals.

References Gandolfo S, Scully C, Carrozzo M (2006) Oral medicine.

• Avoid tobacco in any form – smoked, chewed, or smokeless • Avoid using betel nut (or areca nut), even without tobacco • Cut down on alcohol: aim to drink no more than one standard drink a day (two to three units) for women, or two standard drinks a day (three to four units) for men • Eat at least five servings of fruit and vegetables a day • Protect lips with sunscreen and a wide-brimmed hat, and spend time in the shade, when the sun’s UV rays are strong • Reduce chances of infection with HPV by practising safer sex.

Disclosure This series offers a brief synopsis of the diagnosis and management of mouth ulceration – a complex topic that includes common disorders, and less common but lifethreatening conditions. It does not purport to be comprehensive, and the series may include some illustrations from books written or co-authored by the author and colleagues from UK and overseas, published by ElsevierChurchill Livingstone, Wiley-Blackwell, or Informa/Taylor & Francis – all of whose cooperation is acknowledged and appreciated.

Published with permission from Private Dentistry September 2014

60 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 10, NO. 4

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PRODUCTS

HEMOSTYP

DMG

TOPICAL HEMOSTATIC DRESSING HemoStyp is a topical haemostatic agent that is made from treated and sterilised cellulose that is available in fabric meshwork. It is listed on the ARTG with a Type IIa classification, indicated for the control of bleeding from open wounds and body cavities. The material does not contain any chemical additives, thrombin or collagen and is hypoallergenic.

HemoStyp can be used to achieve haemostasis almost instantly.

• Extraction sockets

• Orthognathic surgery

• Protection of sockets

• Endodontic surgery

• Bone grafting

• Other oral surgery procedures

Upon contact with blood, saline or water, HemoStyp converts to a collagen-like substance that adheres to damaged platelets. It also increases the viscosity of the blood at the wound site. This slows down the current of blood, which allows the clotting factors to interact sooner with each other to form a blood clot, hence accelerating the clotting cascade.

Available in 20 Dental Blister Packs with two square pieces that can be cut to size required.

FLAIRESSE The perfect combination for your prophylaxis - Protection instead of filling. Preserving instead of drilling. Not only dentists, but patients too, are relying increasingly on preventative action.

Professional tooth cleaning at the dental office plays an important role. A paste for removing plaque and stains. Gel or foam: for intensive remineralisation of the enamel.

Flairesse Prophy Paste • Does NOT splatter • 3 different grits • Contains Xylitol and Fluoride • 2 fresh Flavours; Mint and Melon • For a perfect cleaning and polishing effect Flairesse Gel & Foam • Increase enamel resistance against acid attacks • Contains Xylitol and Fluoride • Does not drip • Short application time: only 1 Minute • Can be used in a tray • 3 fresh Flavours: Mint Melon and Strawberry

QUINTESSENCE BOOKS

HALAS

HYDRATING LATEX GLOVES

COMPREHENSIVE ESTHETIC DENTISTRY Florin Lazarescu Nothing can replace the sense of professional fulfillment and personal reward that comes from successfully restoring a patient’s smile. This book, which serves as a complete primer on esthetic dentistry, is aimed at that precise reward.

Informed by the latest scientific research and clinical evidence, the authors provide readers with keen insight into the artistic aspects essential to achieving a truly esthetic outcome. Preliminary chapters cover esthetic analysis, effective treatment planning, use of digital dental photography, and the importance of interdisciplinary collaboration. Further chapters outline effective treatment protocols, including the principles of ultraconservative restoration, tooth whitening, anterior and posterior all-ceramic restorations, in-office CAD/CAM technology, implant placement and soft tissue management in the esthetic zone, and the usage of minimally invasive procedures. This book, in its extensive knowledge and passionate voice, represents the union of function and beauty in dentistry, and in doing so, established itself as a comprehensive resource in the field of dental esthetics.

Q-5120789

364 pp; 791 illus.

Contains Shea Butter & Aloe Extract to Moisturise and Protect. Manufactured to AS/NZS 4011.

Both Shea Butter and Aloe extract are known for their healing and moisturising qualities. Shea butter extract also contains anti-inflammatory agents. So while you are working, so are your gloves.

Being a high quality glove they are thin enough to ensure excellent tactile sensitivity, yet have high tensile strength and elongation, which means they won’t tear easily. Finger textured surface & powder free.

Green in colour.

Box of 100

GC

FUJI BULK Fuji BULK is a robust, rapid-setting, multipurpose auto-cure glass ionomer cement (GIC) designed to meet the challenge of bulk placed restorations in more acidic oral environments.

Truly remarkable in its formulation, Fuji BULK provides a unique balance between restoring function and protecting surrounding tooth surfaces from acid challenges.

No conventional glass ionomer cement sets quicker than Fuji BULK, giving you freedom to move faster without compromising working time, cavity adaptation, adhesion or handling. Fuji BULK quickly seals and restores and is ready for final finishing just 2 minutes after start of mix.

Fuji BULK is available in a universal shade and is indicated for any restoration where speed, acid resistance and bulk cure are priorities over aesthetics.

All products available from: HENRY SCHEIN HALAS • Tel: 1300 65 88 22 • www.henryschein.com.au 62 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 10, NO. 4

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The South African Society of Endodontics & Aesthetic Dentistry

Endodontic Excellence at the Apex of Africa

SPEAKERS Christine Berthold (Canada) Arnaldo Castellucci (Italy) Bernard Friedland (USA) James L Guttman (USA) Markus Haapasalo (Canada) Sergio Kuttler (USA) DIAMOND

Martin Levin (USA) Francesco Mangani (Italy) John Meechan (UK) Yoshitsugu Terauchi (Japan) Martin Trope (USA) Peet van der Vyver (South Africa) BRONZE

SPONSORS

3-6 June 2016, Cape Town, South Africa www.ifea2016.com

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PRODUCTS

GC

KOMET

TWO-STEP GREEN STATE ZrO2 POLISHER

CERASMART

Thanks to its dual working part and its special shape, this new “2 in 1” polisher is ideally suitable for work on pre-sintered zirconium oxide frameworks. The grey zone of the polisher is covered with a coarse polishing agent. It allows quick and controlled removal of stumps. The white tip of the working part is much finer. It is designed for retouching occlusal and interdental areas or crown margins.

The polisher should be used at an optimum speed of 6.000 rpm to allow stress-free and precise guidance of the instrument. The zirconia blank benefits from the gentle, conservative function of the instrument. The risk of inadvertent damage to the chalk-like texture of the blank is greatly reduced and the smooth surfaces created by the polisher minimize the need for time-consuming retouching after sintering.

Advantages in a nutshell: • one polisher for two polishing steps • comfortable and precise work • gentle on surfaces K-9706104070

The genius behind GC’s force absorbing hybrid ceramic is the development of a unique technology to manufacture a block with high density of ultrafine glass particles.

Uniform dispersion (short inter-particle distance) of individually silanated and bonded particles is key to delivering CERASMART’s exceptional strength, polish retention and wear resistance.

CERASMART is easy to finish, retaining its beautiful high gloss over time CERASMART opalescence ensures natural shade integration for highly aesthetic restorations.

High fracture toughness CERASMART buffers masticatory pressure and sustains more challenging clinical situations.

Superior wear resistance Independent research showed that CERASMART has very low wear loss under laboratory testing.

QUINTESSENCE BOOKS

INSTRUMENTARIUM

THE SCIENCE AND ART OF OCCLUSION AND ORAL REHABILITATION

EXPRESS™ ORIGO

Martin Gross This exhaustive book provides an overview both of current scholarly concepts and of contemporary clinical practices for managing occlusion in restorative dentistry. With an emphasis on clinical historical content, the book explains the rationale behind treatment concepts and provides evidence-based protocols for simple treatments (e.g., single restorations) to the most involved cases (e.g., fixed and removable prostheses). Featuring overviews of the relevant biological systems and the fundamentals of occlusion as well as pertinent contemporary cases presented by their original practitioners, this book offers detailed, up-to-date information on all aspects of occlusion and oral rehabilitation.

Q-5120790 544 pp; 3,406 illus

An ideal solution for general dentistry The latest addition to the intraoral product family, the EXPRESS™ Origo imaging plate system, shows diagnostic information even in the smallest detail.

The EXPRESS™ Origo imaging plate system is tuned to produce high contrast and good grey levels repeatedly – regardless of the accuracy of the X-ray exposure settings.

The EXPRESS™ Origo imaging plate system is an ideal solution for a General Practitioner working in a small or medium-sized private clinic. Comfortable imaging plates are as easy to position as film and there is no risk of breaking cables. Fluent and smooth workflow make EXPRESS™ Origo imaging plate system really stand out. Use of the system is easy to learn, and a digital image is available in just seconds. Just insert the plate!

PHILIPS

VITA

EASYSHADE V

SONICARE AIRFLOSS ULTRA Philips Sonicare AirFloss Ultra is clinically proven as effective as string floss in improving gum health*.

•Reduces plaque significantly than manual brushing alone1 •Cleans entire mouth in 60 sec •Improves gum health in 2 weeks *When used in conjunction with a manual toothbrush and antimicrobial rinse in patients with mild to moderate gingivitis. AirFloss is designed to help inconsistent flossers develop a healthy daily interdental cleaning routine. For more information, please visit www.philips.com/airfloss/faq 1.Amini P, Gallob J, Olson M, Defenbaugh J, Souza S, Mwatha T, Jenkins W, Ward M. Data on file, 2014

Optimum shade determination, maximum reliability.

High-precision ensures that the digital focus remains squarely on tooth-shade determination and communication.

Thanks to a complete redesign, VITA Easyshade® V has a truly striking appearance. The seamless casing, layered structure of the internal components as well as the shortened measurement tip ensure maximum ergonomics that fit naturally in your hand.

Determine your patients' tooth shade for selecting CAD/CAM materials, fabricating layered crowns, selecting prosthetic teeth, choosing the materials for direct fillings, and planning aesthetic corrections using veneers.

Support professional tooth bleaching through digital documentation.

The user-oriented operating concept is rounded off perfectly by a brilliant colour LED touch display that is both convenient and intuitive.

All products available from: HENRY SCHEIN HALAS • Tel: 1300 65 88 22 • www.henryschein.com.au 64 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 10, NO. 4

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