International Dentistry Australasian Edition - Vol. 10 No. 3

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VOL. 1 0 NO. 3 IN THIS ISSUE Alejandro Lanis and Orlando Ă lvarez del Canto Shortening guided surgical implant times based on a combination of CBCT and digital surface scanners Scott D. Ganz 3-D Virtual planning concepts: Maxillary implant supported removable or fixed prostheses Johan Hartshorne Is implant placement a risk in patients with increased susceptibility to periodontitis?

Carine Tabarani, Raffaele Volpi, Fawzi Riachi Guidelines for treatment of bisphosphonate- induced avascular osteochemonecrosis of the jaws: A comparative literature review and 2 case reports Gregori M. Kurtzman Restoration of endodontic teeth: An engineering perspective Crispian Scully Making sense of mouth ulceration: part eight

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Contents Volume 10 No. 3

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Clinical

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Clinical

Shortening guided surgical implant times based on a combination of CBCT and digital surface scanners Alejandro Lanis and Orlando Ă lvarez del Canto

3-D Virtual planning concepts: Maxillary implant supported removable or fixed prostheses Scott D. Ganz

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26 Clinical

Is implant placement a risk in patients with increased susceptibility to periodontitis?

Johan Hartshorne

32 Case Report

Guidelines for treatment of bisphosphonate- induced avascular osteochemonecrosis of the jaws: A comparative literature review and 2 case reports Carine Tabarani, Raffaele Volpi, Fawzi Riachi

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Clinical Restoration of endodontic teeth: An engineering perspective Gregori M. Kurtzman

58 Clinical

Making sense of mouth ulceration: part eight Crispian Scully

62 Products

VOL. 10, NO. 3 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION 1

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The National Dental Foundation – lack of funding won’t keep them down

Vol. 10 No. 3 ISSN 2071-7962 PUBLISHING EDITOR Ursula Jenkins

The National Dental Foundation (NDF) was founded in 2004. It is a dentist initiated registered charity, acting as a focal point for charity work in the Australian dental industry. The Foundation has been incorporated and has received ATO Endorsement as a Public Benevolent Institution.

The NDF aims to provide dental treatment to Australians who do not have access to care. It also gives dentists who would like to volunteer a vehicle to be able to do so without leaving the comfort of their own practice. Since 2004 the NDF has continued to grow and in 2014 the dental treatment provided hit $467,339.50.

Previously, the Federal Government realised how important organisations like NDF are. They had the foresight to see that people being treated were alleviating an issue in Australia where people who cannot afford to see a dentist just go without. The NDF received government funding between 2012 and 2015. This funding sadly came to an end in June and the NDF now needs to raise money to keep the Foundation running at the current level. They have been networking across Australia and hope to privately fund the Foundation.

Henry Schein Halas, through the Henry Schein Cares Foundation, has always supported the NDF and the dentists who take part in the volunteer days. In May, the company held a sale day where a percentage of sales were donated to the NDF and were pleased to be able to hand over a cheque for $14,000.

Henry Schein Halas thanks all who supported the Sale Day, therefore allowing them to support the NDF in their plight to better the dental situation for all Australians.

Would you like to become a volunteer? Contact the NDF national coordinator by emailing headoffice@nationaldentalfoundation.org.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 Dr William H Liebenberg 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.

Mike Covey, Managing Director of Henry Schein Halas (right), hands David Digges, National Chairman of National Dental Foundation (left), the donation of $14,000 raised by Henry Schein Halas during the May Sale Day. 2 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 10, NO. 3

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

Shortening guided surgical implant times based on a combination of CBCT and digital surface scanners Alejandro Lanis1 and Orlando Álvarez del Canto2

Introduction The introduction of digital surface scanners to the dental field and the simplicity of data transfer are closing the gap in the creation of a completely “virtual patient” with the optimisation of the digital treatment workflow.1 Something that a few years ago sounded like science fiction in dentistry, is possible today owing to the technological advances that have been incorporated into our field. The prosthetic, surgical, radiological and laboratory worlds are being fused in sophisticated digital platforms, enabled by the capacity to import the data obtained from digital surface scanners and the DICOM files into surgical and prosthetic planning software.2–4 The complete digitalisation of patients’ information and the possibility to combine it offer several advantages to clinicians and are changing the way in which patients perceive invasive dental treatments. Because of their advantages in providing personalised treatment, intra-oral scanners for digital impressions and surgical simulation software will be used as a fundamental technology for diagnosis, planning, treatment and prevention.5

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Alejandro Lanis, DDS, MS, Private Practice, Santiago, Chile.

Email: alelanis@umich.edu.

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Orlando Álvarez del Canto, DDS, MS, Associate Professor of Oral Implantology, Universad del Desarrollo, Chile.

Private Practice, Santiago, Chile.

Email:dr.alvarez@oseintegration.cl.

Drs Alejandro Lanis & Orlando Álvarez del Canto Office 601, Av. Presidente Kennedy 7100, 7650618 Santiago de Chile Tel: +56 2 2655 9080

Figure 1: ProMax 3D s CBCT imaging unit.

(Source of the image: www.planmeca.com)

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Figure 2: Digital surface scanner (TRIOS Cart solution, 3Shape).

(Source of the image: www.3Shape.com)

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Figure 3a: A CBCT scan of the mandibular left quadrant. Figure 3b: Surface scanning of the edentulous zone. Figure 3c: Digital reconstruction of the mandibular left quadrant after the surface scanning process. Figure 3d: The digitally reconstructed arches in maximum intercuspation.

Case report A 55-year-old healthy female patient presented to our practice desiring mandibular molar rehabilitation. She complained about the absence of a mandibular left first molar (tooth 36) owing to an extraction performed several years ago because of failed endodontic treatment. After a complete diagnostic evaluation, including clinical and photographic analysis, a CBCT scan of the left mandible

was performed using ProMax 3D s (Planmeca; Figs. 1 & 3a). At the same appointment, a digital surface scan of the left maxilla, left mandible and of both arches in maximum intercuspation to establish interocclusal contact was done with a TRIOS digital scanner (3Shape; Figs. 2 & 3b–d). Once all the diagnostic information had been gathered, a treatment appointment was made for the next day.

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Figure 4a: A lateral view of the initial digital crown design. Figure 4b: A lateral view of the maxillae and the mandible in maximum intercuspation with the virtual crown design. Figure 4c: An occlusal view of the final crown design. Figure 4d: A lateral view of the final crown design.

Figure 5: Multiple views of the 3-D digital implant positioning.

Note how the designed virtual crown was used as a digital radiographic template.

The digital scan files and the DICOM files obtained from the CBCT were imported into the Implant Studio software (3Shape), in which an innovative technique of spacial recognition allows the creation of a 3-D superimposition of the real intra-oral situation and the radiographic images.

A restorative design tool included in Implant Studio was utilised to create a functional and aesthetic virtual crown with the ideal prosthetic position on the reconstructed surface image (Figs. 4a–d). After the final crown evaluation, the 3-D digital implant position was defined to obtain the most convenient prosthetic and surgical result, respecting vital structures, such as the inferior alveolar nerve and vascularity. Thus, the designed virtual crown was used as a radiographic template (Fig. 5).

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Figure 6a: Implant planning performed using an intra-oral surface scan.

Figure 6b: Implant planning checked with the cone beam 3-D reconstruction.

The planning can be performed using an intraoral surface scan and can be checked with the cone beam 3-D reconstruction at the same time, assuring the optimum

implant position and avoiding any bone fenestration or dehiscence (Figs. 6a & b).

The implant selected was a Tapered Internal implant

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Figure 7a: A lateral view of the guide design. The green line shows the future guide margin. Figure 7b: The orange cylinder showing the screw exit for the future restoration. Figure 7c: Virtual 3-D reconstruction of the surgical guide showing the screw exit of the future restoration. Figure 7d: An angled view of the final surgical guide design and the insertion axis of the implant.

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Figure 8a: A lateral view of the final surgical guide design. Figure 8b: An occlusal view of the final surgical guide design. Figure 8c: Processed images (reconstructed STL files) ready for the 3-D printing process. Figure 9: The Objet Eden260V 3-D printer. (Source of the image: www.stratasys.com)

(BioHorizons; D 4.6 mm × L 10.5, platform D 4.5 mm).

Once the implant position had been approved, a teethsupported virtual surgical guide was designed (Figs. 7a–d).

The final guide design was sent as an STL file (Figs. 8a–c) to the 3-D print manufacturer, where the surgical guide was fabricated in two hours (Objet Eden260V, Stratasys; Fig. 9).

Once the guide had been fabricated, a final try-in was performed on the study model to assess any fit inaccuracies or surgical access problems before sterilising the guide and the BioHorizons guided surgery kit (Fig. 10a).

The next day, the patient returned to our practice for the surgical procedure. After a mouth rinse with 0.12 %

chlorhexidine gluconate (Oralgene, Laboratorios Maver) for 2 minutes and the disinfection and preparation of the surgical field, local anaesthetic was delivered to the edentulous area (tooth 36 region) by buccal, crestal and lingual infiltrations (2 % lidocaine hydrochloride and1:100,000 epinephrine).

After a few minutes, the surgical guide was placed in position and the 4.6 mm-diameter guided tissue punch was utilised through the master cylinder placed in the surgical guide at 1,200 rpm. The guide was then removed and the sectioned soft tissue was removed with a tissue elevator and kept in saline solution (Figs. 10b–d).

The surgical guide was repositioned and a 2.0 mm

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Figure 10a: Pre-op surgical guide check on a study model. Figure 10b: Surgical guide positioned in the surgical site. Figure 10c: A guided tissue punch was utilised for the soft-tissue removal. Figure 10d: Removal of the excised soft tissue.

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Figure 11a: The 2.0 mm guided key in position in the master cylinder in the surgical guide. Figure 11b: The 2.0 mm pilot guided drill was used to begin the osteotomy. Figure 11c: The 4.1 mm tapered guided drill was used to widen the osteotomy. Figure 11d: The surgical site showing the osteotomy without the surgical guide. Figure 11e: The guided implant driver and drill stop key with the Tapered Internal implant. Figure 11f: Guided implant placement.

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Figure 12a: The implant placed in final position. Figure 12b: A healing abutment was placed. Figure 12c: A small connective tissue graft was placed in a buccal wedge to create denser and thicker keratinised tissue around the implant. Figure 12d: A post-op periapical radiograph of the implant.

diameter guided key was placed into the master cylinder. A pilot guided drill of 21 mm in length and 2.0 mm in diameter was utilised to start the osteotomy at 1,200 rpm through the guided key cylinder. The surgical guide system compensates 10 mm in actual drill depth so the final osteotomy in this situation was performed at 11 mm depth (Figs. 11a & b).

The procedure was sequentially repeated with the 2.5 mm guided key and tapered guided drill of 21 mm in length and 2.5 mm in diameter, the 3.2 mm guided key and tapered guided drill of 21 mm in length and 3.2 mm in diameter, the

3.7 mm guided key and tapered guided drill of 21 mm in length and 3.7 mm in diameter, and finally the 4.1 mm guided key and tapered guided drill of 21 mm in length and 4.1 mm in diameter (Fig. 11c).

The surgical guide was then removed to check the osteotomy site (Fig. 11d). The guide was then repositioned and the implant was mounted in the 4.6 mm guided implant driver (Fig. 11e). The implant was placed through the master cylinder at 15 rpm and 50 Ncm torque (Fig. 11f). Once the implant was at the final depth position (Fig. 12a), the guided

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implant driver was removed and a healing abutment (BioHorizons; D 4.5 mm × L 3 mm) was screwed into the implant (Fig. 12b). A small connective tissue graft taken from the soft tissue removed by the tissue punch was then placed in a buccal wedge to gain soft-tissue volume and thickness in the remaining keratinised tissue (Fig. 12c). No sutures were indicated. A postoperative radiograph was taken to evaluate the final implant position.

Conclusion The combination of digital surface scans and CBCT images for virtual planning for implant surgery can be used for safe and effective noninvasive computer-guided implant placement. Implant Studio is a user-friendly realisation of this innovative technology and can significantly reduce the preoperative preparation procedures and treatment times while maintaining surgical accuracy. In this specific clinical situation, the computer-guided surgical preparation and

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surgery took no longer than two days, improving the waiting times associated with conventional CBCT guided surgical systems.

We invite anyone interested in this innovative technology to visit our clinic and specialist CAD/CAM training centre in Santiago in Chile, where participants will be involved in practical clinical cases, be given live surgery demonstrations, and attend lectures about guided surgery procedures and CAD/CAM surgical and restorative technologies.

Readers can find a video of the procedure at the following link: https://www.youtube.com/watch?v= 2gNwAtWE0U&feature=youtu.be

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

Reprinted with permission by Cad/Cam, 2/2014.

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CLINICAL

3-D Virtual planning concepts: Maxillary implant supported removable or fixed prostheses Scott D. Ganz1

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Dr Scott D. Ganz maintains a private practice for prosthodontics, maxillofacial prosthetics, and implant dentistry in Fort Lee, New Jersey, USA. He has served as President of the NJ Section of the American College of Prosthodontists and the Computer Aided Implantology Academy (CAI). He has served as President of the New Jersey Section of the American College of Prosthodontists and of the Computer Aided Implantology Academy.

“Pre-surgical prosthetic planning” can be defined as the process of accumulating diagnostic information to determine which course of treatment should be considered for the fully edentate patient. The first step in patient evaluation should include conventional periapical radiographs, panoramic radiographs, oral examination, and mounted, articulated study casts. In the completely edentulous patient it is essential for the clinician to assess several important aspects of the individual anatomical presentation including vertical dimension of occlusion, lip support, phonetics, smile line, over-jet, overbite, ridge contours, and a basic understanding of the underlying bone structures. The accumulation of preliminary data afforded by conventional diagnostics provides a foundation to prepare a course of treatment for the patient.

However, if the review of findings is based upon a two-dimensional panoramic radiograph, it may not be accurate in appreciating the true spatial positioning of vital structures such as the incisal canal, the floor of the nose, or the maxillary sinus. To fully understand each individual patient’s actual bone anatomy, it is essential that clinicians adopt an innovative set of virtual, three-dimensional tools. Through the use of advanced imaging modalities new paradigms have been established that in the author’s opinion will continue to redefine the process of diagnosis and treatment planning dental implant procedures for years to come. Without the application of computed tomography (CT) or lower radiation dosage cone beam computed tomography (CBCT), an understanding of the three-dimensional anatomic reality cannot be accurately determined, potentially increasing surgical and restorative complications.

The utilization of 3-D imaging modalities as part of pre-surgical prosthetic planning can take several paths. The first involves acquiring a three- dimensional scan directly, without any prior planning or ancillary appliances. The scan process can be accomplished at a local radiology centre, mobile imaging company, or via an inoffice CBCT device. The scan itself can be completed within several minutes. Once the data is processed, it can be viewed on the native software of the CBCT machine itself, evaluated for potential implant receptor sites, followed by the surgical intervention, or with a third party interactive treatment planning software. A second path requires the fabrication of a radiopaque “scannographic” appliance that incorporates vital restorative information that will be worn by the patient during the acquisition of the scan. In this manner, the desired tooth position can be evaluated in relation to the underlying bone and other important anatomic structures such as the maxillary sinus or the inferior alveolar nerve. Certain proprietary methods incorporate the use of fiducial markers to help with the registration process for planning based directly upon the restorative needs for the patient.

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Figure 1: The axial view provides insight into the global topography of the maxilla.

Figure 2: The volumetric rendering aids in the inspection of the bone, but does not offer information on the desired restorative position.

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Figures 3a and 3b: A radiopaque scanning appliance fabricated from a duplicate of a patient’s existing well-fitting denture (a) allows inspection of tooth position in relation to the underlying bone (b).

The use of interactive treatment planning has expanded dramatically in the past ten years as computing power has increased exponentially. As defined by the author, guided surgery can be divided into three distinct categories once a “virtual” plan has been established based on 3-D scan diagnosis (Ganz-Rinaldi Classification of Guided Implant Surgery Protocols). The first allows the information to be assessed, providing important information to the clinician who will perform the surgical intervention free-hand based upon the software plan, termed “Diagnostic-Freehand”. The second category involves the fabrication of a surgical guide or template that is remotely constructed from the digital plan usually through rapid prototyping or stereolithography, CAD/CAM, or laboratory fabricated, termed CT-derived “Template-Assisted”. The drilling process is started and can be completed within the template helping to control trajectory and depth with the proper instrumentation. The third category requires a specific template design that allows for accurate drilling and osteotomy preparation, and with the proper manufacturer-specific carriers the implants

can then be accurately delivered through the template, termed, "Full Template Guidance." The use of advanced imaging modalities for pre-surgical prosthetic planning is essential for any type of implant surgical and restorative intervention, from the single tooth, multiple tooth restoration, full arch fixed and removable overdenture reconstruction.

However, it is the correct use of three-dimensional tools that provides clinicians with the power to diagnose and treatment plan with the highest degree of acuity and accuracy.

3-D Planning Concepts: Full Arch Maxillary Overdenture Due to anatomical variations related to the maxillary sinus, the floor of the nose, the incisal canal, the facial trajectory of the anterior segment, thin cortical plates, and diminished overall bone density when compared to the mandible, the completely edentate maxilla offers additional diagnostic challenges for clinicians. The axial view provides insight into the global topography of the maxilla (Fig. 1). The position

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Figures 4a-c: Cross-sectional slice reveals tooth position in relationship to the bone (a) and the extension of the labial vestibule (red arrow) (b). The relationship to the maxillary sinus is essential for planning in the posterior region, where thin cortical plate can be clearly visualized (arrow) (c). Figures 5a & b: Evaluating a potential receptor site within the cross-sectional view (Slice 63) (a). The positioning of the implant(s) need to fall within the envelope of the teeth (b). Figures 6a-c: The cross-sectional image reveals a potential receptor site (a); the realistic implant and abutment simulation (b); the author’s preference places the implant within a defined zone of available bone defined as the “Triangle of Bone” (TOB) that also acts to relate implant position to the restorative outcome (c).

of the incisal canal can be visualized, along with thin facial and palatal cortical plates. The volumetric rendering aids in the inspection of the bone, but does not offer any information regarding tooth or ultimate restorative position (Fig. 2). In order to achieve the concept of “true restoratively driven implant dentistry” pre-surgical prosthetic planning should start prior to any scan being taken. A scanning appliance can be fabricated from a duplicate of a patient’s existing well-fitting denture, or a new diagnostic set-up which positions the teeth at the ideal vertical dimension of occlusion, centric relation, and functional/aesthetic components (Fig. 3a). The patient wears the scannographic appliance during the scan, ideally held in place with a pre-determined bite registration to minimize movement. The scan reconstruction will then contain both the tooth position

and the underlying bone (Fig. 3b).

The combination of the anatomical scan data with the radiopaque template allows unprecedented diagnostic potential. The template reveals the tooth position (red arrows) in relationship to the underlying bone in the cross-sectional slice (Fig. 4a). The thin cortical plates can be clearly visualized, along with the extension of the labial vestibule (red arrow, Fig. 4b). The relationship to the maxillary sinus is important when deciding if implants might be an option in the posterior region (Fig. 4c). In this example the pneumatisation of the sinus has resulted in extremely thin lateral cortical plate (see red arrows). The radiopaque template is helpful when evaluating other receptor sites, and positioning a simulated implant within the cross-sectional view (Slice 63, Fig. 5a). For an over-denture application the

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Figures 7a & b: The occlusal view of the volumetric rendering aids in the implant-to-implant positioning within the bone (a).

Superimposing a translucent scannographic template over the maxilla provides the information to position implants within the restorative envelope (b). Figures 8a & b: Use of “selective transparency” with abutment extensions above the occlusal plane (a). Ball abutments positioned at the proper tissue cuff height (b). Figures 9a & b: Rotating the views help position implants where they will best support the removable prosthesis.

positioning of implants need to fall within the envelope of the teeth, and it is even more practical to visualize the abutments that might be utilized (Fig. 5b). For this example a realistic stock “ball type” abutment was utilized on the virtual realistic implant. In order to provide some guidance, it is the author’s preference to place the implant within a defined zone of available bone (Figs. 6a & b). This zone has been previously defined as the “Triangle of Bone” (TOB) that also acts as a decision tree to connect the implant placement to the restorative outcome (Fig. 6c). Positioning the implant within the zone of the TOB, or actually bisecting the triangle, allows for the most bone volume to surround the implant. Following this formula, the implant and abutment will be positioned in a favourable restorative position.

Further inspection through the utilization of additional views can be extremely enlightening with regard to the final positioning of the implants. The occlusal view of the volumetric reconstruction aids in the implant-to-implant positioning within the bone (Fig 7a). However, without a complete understanding of the tooth position, the implants may not be ideally located based upon the prosthetic plan.

Superimposing a translucent scannographic template over the maxilla provides the important information to position the implants within the restorative envelope (Fig. 7b). The

prosthesis design can be evaluated to determine whether to fabricate a complete denture that would extend to incorporate a conventional post-palatal seal, or an open palate horseshoe type prosthesis. To aid in the final positioning, it is helpful to visualize the outline of the occlusion using the author’s concept of “selective transparency”, and extend the abutments above the occlusal plane (Fig. 8a). “Selective transparency” is a software tool which can help separate one anatomical structure from another by adjusting the opacity of the various objects. Once the implants are placed, the ball abutments can then be positioned at the proper tissue cuff height (Fig. 8b). Rotating the views can substantiate the plan to place the implants where they will be support the removable prosthesis (Figs.

9a & b).

It is important to assess the clearance within the denture to allow for sufficient thickness of acrylic within the over-denture abutment housing avoiding potential fracture of the prosthesis. This “prosthetic space” requirement may be different depending upon the type of attachment used. Using the power of digital technology and selective transparency, the realistic implant and ball abutment can be seen through the prosthesis and the underling bone (Figs. 10a & b). These illustrations reveal that the two right implants are parallel,

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Figures 10a & b: Selective transparency allows the realistic implants and ball abutments to be seen through the prosthesis and the maxillary bone. Figure 11: The distance between the two anterior implants and the maxillary incisor teeth (red arrows) represents a cantilever that could result in tipping of the denture. Figures 12a & b: The use of realistic attachments allows for implant-to-implant positioning around the arch necessary to gain maximum retention and resistance of the prosthesis to dislodgement during mastication. Figure 13: Utilization of virtual abutments aids in determining the correct tissue cuff heights of the abutments above the bone, and through the soft tissue

while the left implants are seen to follow the natural trajectory of the maxillary alveolus (a), and the reverse is true after rotating the maxillary volumetric reconstruction to view the left side (b). Finally, when considering the mechanical forces of mastication and movement of the prosthesis, a line can be drawn between the two most anterior implants that establishes the potential for rotation in the occlusal plane (Fig. 11). A second line can be drawn at the most anterior aspect of the maxillary teeth. The distance between the two anterior implants and the maxillary incisor teeth (red arrows) represents a cantilever that could result in tipping of the denture when the patient bites into an apple.

The ball-abutment is only one potential stock abutment choice for an over-denture application. Another widely used abutment is the Locator attachment (Zest Anchors). The use of realistic Locator attachments allows for a precise understanding of the implant-to-implant relationship, and spacing around the arch which is necessary to gain maximum retention of the prosthesis to resist dislodgment during mastication (Figs. 12a & b). In addition, the utilization of virtual abutments aids in determining the correct tissue cuff heights of the abutments above the bone, and through the soft tissue (Fig. 13). The vertical distance can be evaluated

within the framework of the prosthetic design (Fig. 14a). The new digital tools allow for new paradigms to be established assessing the relationship of the implant position, abutment position, and prosthesis prior to the scalpel ever touching the patient. Crown-to-root ratios and the trajectory of the implant-abutment complex can be visualized within the virtual plan, providing valuable surgical and restorative information during the planning phase (Fig. 14b).

In addition to the axial, panoramic, and three-dimensional reconstructed volume, the importance of the cross-sectional image is critical to fully appreciate the relationship between the implant position within the bone, and the emergence through the tooth. One area that has not been emphasized however, is the ability to determine the prosthetic space required for the abutment as it relates to the thickness of soft tissue supporting the overdenture (Fig. 15a). The realistic ball abutment can be clearly visualized sitting on the coronal aspect of the implant (red line), and the tissue cuff height of the abutment (green line). One component that is not easy to determine is the metal housing that will be processed within the denture. This component part is not yet available within the software libraries to the author’s present knowledge.

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14a

15a

14b

15b

16

Figures 14a & b: The vertical distance can be evaluated within the prosthetic design (a), crown-to-root ratios, and the trajectory of the implant-abutment complex can be visualized within the virtual plan. Figures 15a & b: The top of the implant (red line) serves as the foundation for the abutment at a specific tissue cuff height (green line) (a); the metal housing represented in gold also has a vertical component (yellow line) (b). Figure 16: Once the implant position has been confirmed, the software will generate the virtual design of the template.

Therefore an approximation was digitally represented (gold), so that the extra height can be visualized (yellow line), revealing the thin palatal aspect of the overdenture (Fig. 15b). Once the virtual plan has been established a surgical template can be designed by the software and then fabricated through 3-D printing, stereolithography, or a CAD/CAM process to assist in the placement of the implants within the anticipated restorative needs of the patient (Fig. 16).

3-D Planning Concepts: Full Arch Maxillary Fixed Prosthesis There are few differences between 3-D planning concepts for an overdenture prosthetic design, or a fixed prosthetic rehabilitation supported by implants. All aspects of the patient’s bone and soft tissue anatomy must be carefully evaluated. After a proper assessment of the available bone, key implant positions are identified, and simulated within the

3-D reconstructed volume as seen in Figure 17a. However, it is important to once again evaluate the potential implant receptor sites based upon the envelope of the occlusion (Fig. 17b). Using “selective transparency” helps to provide an enhanced perspective of how the implant abutment projections (yellow) are spaced within the desired restoration (Fig. 17c). The frontal view clearly illustrates the importance of the implant abutment projections, revealing for this example a nearly parallel placement of the implants (Figs.

18a & b). “Selective Transparency” can be applied to multiple structures, to help visualize the entire complex of the implant, abutment projection, radiopaque template, and the underlying bone (Fig. 18c). By rotating the 3-D reconstructed volumes, it is apparent how powerful these interactive software tools can be (Figs. 19a & b). Once the final positions of the implants are confirmed for the edentulous presentation, a mucosal-supported template can be designed and fabricated through 3-D printing, stereolithography, or a

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Figures 17a-c: Eight implants positioned to support a fixed restoration (a) to fit within the framework of the desired tooth position (b); using “selective transparency” the underlying bone can be visualized (c). Figures 18a-c: Frontal view of the scanning template with yellow abutment projections seen above the occlusal plane (a); semi-transparent scanning template (b); and all three objects translucent to visualize the position of the implants within the bone (c).

CAD/CAM process. The mucosal-supported template should be fixated to the bone, to insure accuracy of the drilling sequence. The template with the blue screws can be visualized in Figures 20a–c.

Conclusion The advent of complete denture fabrication evolved into the adoption of over-denture concepts for both natural and

19a

implant supported restorations. Conventional prosthodontic protocols were developed to aid in the diagnosis, treatment planning, and laboratory phase of the reconstruction. These included conventional periapical radiographs, panoramic radiographs, oral examination, and mounted, articulated study casts. The clinician was then expected to assess several important aspects of the patient’s anatomical presentation including vertical dimension of occlusion, lip support,

19b

Figures 19a & b: Another 3-D view showing the emergence of the abutment projections through the scanning template.

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20a

20b

20c

Figures 20a-c: The template design revealing the guide tubes (a); three blue fixation pins (b); and the entire complex on the 3-D reconstructed volume (c).

phonetics, smile line, overjet, overbite, ridge contours, and a basic understanding of the underlying bone structures. The accumulation of preliminary data afforded by conventional diagnostics provided a foundation to prepare a course of treatment for the patient. However, the conventional review of findings was based upon a two-dimensional assessment of the actual patient’s bone anatomy. To fully understand each individual patient’s presentation, this article provided clinicians with an appreciation of various innovative virtual, three-dimensional tools based upon the use of advanced three dimensional imaging modalities for both removable and fixed prosthetic treatment alternatives.

The application of CBCT and interactive treatment planning software, empowers clinicians with an accurate understanding of the three-dimensional anatomic reality for our patients as an aid in providing state-of-the-art treatment.

Implants will be better positioned, with fewer surgical and restorative complications, and reduced laboratory remakes based upon these improved diagnostic tools. The benefits

will enable clinicians to better understand the relationship between patient anatomy and the desired restorative outcomes, in the process of achieving true restorative driven implant reconstruction. The ability to utilize digital imaging and treatment planning technology is now within the reach of most clinicians through the various software products that are on the market. In addition there are many third party outlets through internet portals that enable clinicians to upload their DICOM data for evaluation, processing, treatment planning, and even surgical template fabrication without actually owning the planning software. New paradigms have been established that, in the author’s opinion, will continue to redefine the process of diagnosis and treatment planning dental implant procedures, both removable and fixed alternatives for years to come. Please remember though that the “template is only as good as the plan”.

Reprinted with permission by Cone Beam, 2/2015.

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Is implant placement a risk in patients with increased susceptibility to periodontitis?

Johan Hartshorne1

A critical appraisal of a systematic review: Chrcanovic BR, Albrektsson T, Wennerberg A, Periodontally compromised versus periodontally healthy patients and dental implants: a systematic review and meta-analysis, Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.09.013 Article accepted: 25-9-2014 (Origin of research – University of Malmö, Sweden)

Summary Systematic review conclusion: The present study suggests that an increased susceptibility for periodontitis may translate to an increased susceptibility for implant loss, loss of supporting bone, and postoperative infection. The results should be interpreted with caution due to the presence of uncontrolled confounding factors in the included studies, none of them randomized.

Critical appraisal conclusion: Periodontally compromised patients are at higher risk post-operative infection, marginal bone loss (peri-implant disease) and implant failures in comparison to periodontally healthy patients. The clinical significance and implications of the results of this review should be interpreted with caution due to lack of controlling important confounding factors such as smoking habits that is known to influence the incidence of post-operative infections, peri-implant disease and implant failures.

Implications for clinical practice: It is clinically prudent to accept that patients with a history of chronic periodontitis (susceptible or compromised) are at greater risk for implant related complications and failures. Patients with chronic periodontitis should be assessed and managed on an individual basis when contemplating implant therapy.

The risks are higher in patients with aggressive periodontitis or with co-morbidity factors such as smoking or uncontrolled systemic conditions such as diabetes and immunedeficiency and therefore need extra precautionary measures. Appropriate periodontal therapy, adherence to a strict periodontal maintenance program and limiting comorbidity risk factors are critical for ensuring a predictable and successful treatment outcome with implant therapy.

1

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.

E-mail: jhartshorne@kanonberg.co.za

Clinical question In periodontally compromised patients (PCP’s) receiving dental implants, do postoperative infection, marginal bone loss and implant failure rates differ compared to implants inserted in periodontally healthy patients (PHP’s).

Review methods Methodology This study followed the PRISMA Statement guidelines.1 The methodological quality assessment of the studies was executed according to the Newcastle-Ottawa scale (NOS).2

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Search strategy and study selection The investigators did an electronic search without time or language restrictions in March 2014 of the electronic databases: PubMed, Web of Science, and the Cochrane Oral Health Group Trials Register, to identify papers on the topic in the clinical question. They also conducted a manual search of dental implant-related journals. The reference list of the identified studies and the relevant reviews on the subject were also scanned for possible studies. Online databases (www.clinicaltrials.gov; www.centerwatch.com/clinicaltrials; www.clinicalconnection.com) were also checked for possible clinical trials in progress. Three reviewers independently screened the titles and abstracts identified through the electronic searches for articles related to the focus question. Full text articles of studies appearing to meet the inclusion criteria, or where there were insufficient data in the title and abstract to make a clear decision were obtained and read by all the reviewers.

Disagreements were resolved by discussion between the authors.

Eligibility and exclusion criteria Only randomised controlled trials (RCTs) or controlled clinical trials on humans were eligible for this study. The clinical studies had to compare implant failure rates in PCP’s receiving dental implants compared to PHP’s. Implant failure was defined as the complete loss of the implant. Case reports, technical reports, animal studies, in vitro studies, and reviews papers were excluded from this study.

Outcome measures and data extraction and synthesis Implant failure, postoperative infection and marginal bone loss were the primary outcomes that were measured. The estimates of relative effect for implant failure and postoperative infection were expressed in risk ratio (RR) with a 95% confidence interval (CI). The estimate of relative effect for marginal bone loss was expressed as mean difference (MD) in millimeters with a 95% confidence interval (CI). The data for each variable was used to construct a Forest plot for analysis of the pooled data.

The authors of primary studies were contacted to obtain information on missing data. Whenever outcomes of interest were not clearly stated, the data were not used for analysis.

The statistical unit for the outcomes was the implant.

Appropriate statistical analysis was conducted to determine biases, heterogeneity and differences in outcome measures between PHPs and PCPs. A meta-analysis was only performed on studies with similar comparisons reporting the same outcome measures. Studies lacking information about the relative probability of an event

was automatically omitted from the meta-analysis. A funnel plot was used to estimate publication bias and other biases related to sample size. The choice between fixed-effect and random effects model was based on I2 statistical test for heterogeneity.

Main results A total of 22 publications were included in the meta-analysis.

Ten studies were controlled clinical trials (CCTs) and twelve retrospective analyses. There were no randomized controlled studies. All studies except one were rated as having high methodological rigor however, all were judged to be at high risk of bias. The funnel plot showed asymmetry when the studies reporting the outcome ‘implant failure’ in the comparison between PCPs vs. PHPs are analyzed, indicating possible presence of publication bias. From the 22 studies comparing PHPs and PCPs, a total of 10927 dental implants were inserted in PCPs, with 587 failures (5.37%), and 5881 implants were inserted in PHPs, with 226 failures (3.84%).

A statistically significant increase in implant failure rates was observed with insertion of dental implants in PCP’s compared to PHPs. Pooling of the data showed a RR of 1.78 (95% CI 1.50-2.11) (P <0.00001). When only the CCTs were pooled, a RR of 1.97 resulted (95% CI 1.38 -2.80) also showing a similar statistically significant increase in implant failure rates in PCPs. (P = 0.0002).

Only four studies provided information about postoperative infection. The insertion of dental implants in PCPs or PHPs statistically affected the incidence of postoperative infections in favor of PHPs. A RR of 3.24 (95% CI 1.69-6.21) (P=0.0004) was observed.

Five studies provided information on the marginal bone loss in PCPs and PHPs receiving dental implants (A total of 212 implants were placed in PCPs and 269 implants in PHPs) There was statistically significant difference in marginal bone loss (MD 0.60, 95% CI 0.33-0.87; P < 0.0001) between PCPs and PHPs, favoring PHPs.

Conclusion The present study suggests that an increased susceptibility for periodontitis may also translate to an increased susceptibility for postoperative infection, loss of supporting bone, and implant loss. However, the results should be interpreted with caution due to the presence of uncontrolled confounding factors in the included studies.

The authors did not declare whether they received financial support or whether there was any potential conflict of interest with respect to the authorship and/or publication of this review.

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Commentary Background and importance Dental implant therapy has become a well-established treatment modality with favorable long-term success rates for replacing missing teeth in the general population. With increasing numbers of patients receiving dental implants, it is certain that post-operative complications, incidence of peri-implant disease and implant failures will increase, posing a significant health care problem for both the patient and the clinician. It is also plausible that more patients will receive implants to replace missing teeth lost due to periodontal disease. In an attempt to limit post-operative complications, peri-implant disease and implant failures, increased attention is being placed on understanding the associated etiologic and risk factors.3, 4 Although there is some evidence that patients with a history of periodontitis may be at greater risk for peri-implant disease,5 there is no general consensus regarding its influence on the outcome of implant therapy.3 Further conflicting evidence suggests that although periodontally compromised patients are at greater risk of MBL and peri-implantitis, there is no difference in implant survival rate, between periodontally compromised and periodontally healthy patients.6 Are the results valid?

The authors stated that only randomized controlled trials or controlled clinical trials were eligible for this study. However, 12 of the 22 studies included were retrospective studies. These studies cannot be considered as controlled clinical trials and therefore are rated as a lower level of evidence. There were no randomized controlled trials included in this review, therefore the potential risk for bias in all the studies are great.

Overall there was a marked variability of the results between the individual studies possibly due to differences in sample sizes, population characteristics, and definition of periodontitis. The groups in general were very heterogeneous and not all treated in the same way. The severity of periodontal disease and how it was treated, the time of implant placement, pre-and postoperative periodontal maintenance, healing period and implant loading protocol, differences in prosthetic supra-structures varied amongst the primary studies. Furthermore, not all the studies provided details about the periodontal maintenance and the presence/absence of residual pockets. Another potential limitation was the varying lengths of follow-up time (3-5 years) (median of 5 years). Such relative short follow-up could possibly have led to an underestimation of the estimate of the failure rate.

Wide inclusion criteria generally increase the risk of finding heterogeneity, thus making the analysis and interpretation of confounding factors on results difficult. However, statistical

analysis surprisingly showed no significant heterogeneity between the test and control group. Based on the statistical test the investigators choose to use the fixed-effect model. However, it should be pointed out that the choice between using a fixedeffect and a random-effects meta-analysis should never be made on the basis of a statistical test for heterogeneity.7 The two models are not the same and conceptually measure different things. The decision what statistical model to use should be done at protocol stage based on the knowledge of variability across studies. Choosing a model as done in this study can produce misleading results.

Although a methodological quality assessment was carried using predetermined criteria, it is not reported whether this evaluation was carried out independently by more than one person and what their degree of agreement was. The reviewers did not provide a list of excluded studies and their reasons for exclusion. The lack of control of confounding factors (i.e. smoking habits, periodontal maintenance compliance, untreated periodontal disease, diabetes, use of prophylactic antibiotics and antimicrobial mouth rinses, varying lengths of follow-up, patient ages, number of implants, severity of periodontitis etc.) could modify both post-operative complications, MBL and implant success rate, therefor limiting the potential of this review to draw strong conclusions.

Overall, the high level of variability between individual studies, high risk of bias and lack of controlling confounding factors resulted in poor quality of evidence and therefor we have to question the validity of the results.

What were the key findings?

Implant failures A RR of 1.78 (95% CI 1.50-2.11) (P <0.00001) implies that dental implant failures are 1.78 times likely when implants are inserted in PCPs compared to when implants are inserted in PHPs. When only the CCTs were pooled, a RR of 1.97 resulted (95% CI 1.38 -2.80) also showing a similar statistically significant increase in implant failure rates in PCPs. (P = 0.0002).

Although the implant failure rate was statistically significant and consistently showed less risk of implant failure in periodontal healthy patients, the individual results were clinically insignificant. Most studies had results with very wide CI crossing the line of no clinical difference. This observation can be ascribed to the small sample sizes.

Post-operative infection The insertion of dental implants in PCPs or PHPs statistically affected the incidence of postoperative infections in favor of

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PHPs. A RR of 3.24 (95% CI 1.69-6.21) (P=0.0004) implies that post-operative infection are 3.24 times likely to happen in PCPs compared to when implants are inserted in PHPs. The data for post-operative infection showed some inconsistency. Of the four individual studies that were pooled one study showed that there was statistically significant less post-operative infection in periodontally compromised patients.8 The results of other individual studies included in the meta-analysis can also be considered as clinically insignificant due to small sample sizes.

Marginal bone loss Nine individual studies were included in the subgroup analysis for marginal bone loss. There was statistically significant difference in marginal bone loss (MD 0.60, 95% CI 0.330.87; P < 0.0001) between PCPs and PHPs, favoring PHPs. All, except two of the individual studies were also clinically significant. The clinical relevance or importance of these margins of bone loss has to be questioned. It is also likely the small sample sizes could have distorted the results.

In the final analysis the results of this review should be interpreted with caution due to the presence of several uncontrolled confounding factors. An important consideration that should be mentioned is the possible high influence of smoking habits on post-operative infection, incidence of periimplant disease and implants failure rates. Smokers were included in 14 of the studies reviewed.

Irrespective of the limitations of this study, the findings are in accordance with that reported in other meta-analysis.9, 10 How are the results of this review applicable in clinical practice?

Limiting complications are clinically important and relevant to the patient and the clinician. Therefore, making the correct clinical decisions about risks and benefits of treatment are important because this could mean the difference risking or losing and implant or maximizing a successful treatment outcome.

Wide inclusion criteria generally increase the risk of heterogeneity and thus invalidate generalizability of results if confounding variables are not controlled and analyzed.

However, statistical tests showed no heterogeneity between the test and control groups. If no heterogeneity is found when wide inclusion criteria is used, the results will reasonable be more applicable to the clinical practice situation. However, because confounding factors have not been controlled, caution should be exercised in interpreting and applying the results.

Overall, it is logical to assume that patients with a history of chronic periodontitis are at greater risk for implant related complications and failures and therefore assessed and managed on an individual basis when contemplating implant therapy. For example, some patients on periodontal maintenance may be refractory to treatment and continue to experience complications, tooth loss and implant failures.

Furthermore, patients with co-morbidity factors such as smoking or uncontrolled systemic conditions such as diabetes, osteoporosis and immunodeficiencyâ&#x20AC;&#x2122;s need extra precautionary measures with periodontal maintenance and implant treatment.

The original periodontal diagnosis is important for implant prognosis but the presence of residual pockets and nonattendance of periodontal maintenance during follow-up as well as the presence of smoking habits are important risk factors that may negatively affect predictability and outcome of treatment.11 Maintenance of periodontal health is critical and includes control of periodontal parameters and stabilization of disease progression.

Clinical Resolution The results of this review suggest that compromised periodontal health is an important risk factor for post-operative infection, peri-implant disease and implant failure. However, it should be noted that combining poor quality or overly biased data, unreliable results can occur, therefore any inferences made regarding complications associated with implant placement in patients with increased susceptibility to periodontitis should be done with caution. The presence of residual pockets, smoking and non-compliance to adequate periodontal maintenance may have a negative impact on implant treatment outcome. At this stage of time, the influences of the type and severity of PD on implant loss, peri-implant disease and marginal bone loss remain to be defined. Further research is needed to clarify whether implants can be placed successfully and predictably in patients that are periodontally compromised and whether patients that adhere to a maintenance periodontal program will have a decreased risk of post-operative infection, peri-implant disease, and implant loss. Baseline data should also clearly indicate that periodontal health was achieved prior to implant placement and during the maintenance period. Studies should also extend their follow-up to more than 5 years. New evidence accumulated over time should continuously be reassessed to refine diagnostic and therapeutic treatment protocols and eliminate unnecessary procedures.

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Disclosure 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. 11. Moher D, Liberati A, Tetzlaff J, Altman DG, Prisma Group. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. Ann Int Med 2009; 151:264-9, W64.

2. Wells GA, Shea B, O’Connell D, Peterson J, Welch V, Losos M, et al. The Newcastle– Ottawa Scale (NOS) for assessing the quality of non-randomized studies in metaanalyses. 2000. Available from: http://www.ohri.ca/programs/clinical_epidemiology/oxf ord.asp. Accessed on August 27, 2014.

3. Pjetersson BE, Tan K, Lang NP, Bragger U, Egger M, Zwahlen M. A systematic review of the survival and complication rates of fixed partial dentures (FDPs) after an observation period of at least 5 years. Clin Oral Impl Res 2004; 15: 625-642.

4. Saaby M, Karring E, Schou S, Isidor F. Factors

influencing severity of peri-implantitis. Clin Oral Impl Res. Accepted 16 September 2014. Doi: 10.1111/clr.12505.

5. Renvert S, Persson GR. Periodontitis as apotential risk factor for peri-implantitis. J Clin Periodontol 2009; 36(Suppl. 10): 9-14.

6. Ramanauskaite A, Baseviciene N, Wang H-L, Tözüm TF. Effect of history of periodontitis on implant success: Metaanalysis and systematic review. Implant Dentistry 2014; 23(6): 687- 696.

7. Deeks JJ, Higgins JPT, Altman DG. Analysing data and undertaking meta-analysis. In: Higgins JPT, Green S editors, Cochrane handbook for systematic reviews of interventions.

Chichester, United Kingdom: John Wiley & Sons; 2008.

8. Fardal O, Linden GJ. Tooth loss and implant outcomes in patients refractory to treatment in a periodontal practice.

Journal of Clinical Periodontology 2008; 35:733-8.

9. Safii SH, Palmer RM, Wilson RF. Risk of implant failure and marginal bone loss in subjects with a history of periodontitis: a systematic review and meta-analysis. Clin Impl Dent Rel Res 2010; 12: 165-174.

10. Sgolastra F, Petrucci A, Severino M, Gatto R, Monaco A. Periodontitis, implant loss and peri-implantitis. A metaanalysis. Clin Oral Impl Res. Accepted 19 November 2013. Doi: 10.1111/clr.12319 11. Zangrando MSR, Damante CA, Sant’Ana ACP , Rubo de Rezende ML, Greghi SLA, Chambrone L. Long-Term Evaluation of Periodontal Parameters and Implant Outcomes in Periodontally Compromised Patients. A Systematic Review.

J of Periodontol. Posted online October 2, 2014. (doi:10.1902/jop.2014.140390)

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Guidelines for treatment of bisphosphonateinduced avascular osteochemonecrosis of the jaws: A comparative literature review and 2 case reports Carine Tabarani,1 Raffaele Volpi,2 Fawzi Riachi3 Abstract Bisphosphonates are synthetic non-metabolized analogues of the naturally occurring inorganic pyrophosphate1 ,2 and have an elevated affinity for bone due to their R1-side chain. Despite the benefits related to the use of these medications, osteonecrosis of the jaws is a devastating complication in a subset of patients receiving these chemical drugs.

Recommendations for dental management of patients undergoing bisphosphonate treatment have been developed but until today no specific guidelines exist for the management of patients taking oral and intravenous bisphosphonates.

The purpose of this article is to assess and review the available data on treatment of osteochemonecrosis of the jaw (ONJ), with analyzing the concept of this pathological phenomena, and proposing some new recommendations established by the Italian Society for the Study of Bisphosphonate in Oral Surgery (SISBO) that showed as follows in the two clinical cases a total healing of bisphosphonate-induced osteochemonecrosis of the jaw.

Key words: Bisphosphonate, affinity for bone, jaw, osteochemonecrosis, treatment.

1

DDS, Oral Surg. Dipl.,Oral Path. Dipl., MSc. Lecturer, Topographical Anatomy Dept; Fellow, Dept of Oral and Maxillofacial Surgery, Saint – Joseph University Faculty of Dental Medicine, Beirut, Lebanon.

2

DDS, Oral Surg. Dipl.

Fellow, Dept of Oral Surgery, Tor -Vergata University Faculty of Dental Medicine, Rome, Italy; Chairperson of the Italian Society for the Study of Bisphosphonate in Oral Surgery (SISBO), .

3

DDS, Oral Surg. Cert., Perio.

Cert.

Chairperson, Dept of Oral Surgery, Saint- Joseph University Faculty of Dental Medicine, Beirut, Lebanon.

Corresponding Author Dr. Carine Tabarani Email: ctabarani@hotmail.com

Bisphosphonates are synthetic compounds with chemical structure similar to that of inorganic pyrophosphate, an endogenous regulator of bone mineralization,1 used for the treatment of hypercalcemia in patients with bone metastasis or other disorders such as metabolic bone diseases, Paget's disease,2 and have shown to alleviate many consequences associated with osteoporosis, but still are the main cause of osteochemonecrosis of the jaw.

We can distinguish three generations of bisphosphonate. The first is formed of the non-aminobisphosphonate (Etidronate, Clodronate), the second correspond to the aminobisphosphonates (Pamidronate, Alendronate) that are 100 to 500 times more powerful, and the third generation (Ibandronate, Risedronate and Zoledronate) that is 10 to 20 times more powerful than the previous generations in terms of reducing skeletal-related events (SRE; defined as pathological fracture, surgery to bone and hypercalcemia).3 The addition of nitrogen increases the potency of bisphosphonates in inhibiting bone resorption than non-aminobisphosphonates.4 In recent years, many cases of osteochemonecrosis have been reported involving both oral and intravenous therapy regimens.5 Marx in 20036 described the first case of osteochemonecrosis of the jaw associated with bisphosphonate therapy; since then the number of cases reported is increasing and has become a “growing epidemic”.

The expert panel recommendations should always be incorporated into clinical decision-making when facing a patient undergoing bisphosphonate treatment.

The purpose of this article is to comparatively analyse some guidelines published on the treatment of osteochemonecrosis of the jaw and to expose two clinical cases that showed a complete healing of exposed bone and a symptoms relieve, following the use of SISBO recommendations.

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What is bisphosphonate-induced osteochemonecrosis of the jaws?

Osteochemonecrosis is considered as a complication showing in general terms bone exposure with an uncertain prognosis and low healing rates.

Osteonechemonecrosis of the jaw also called bisphosphonate-associated osteonecrosis7, 8 is defined as an area of exposed bone that persists for more than eight weeks in patients undergoing or underwent bisphosphonates treatment.

ONJ can be defined according to 5 criteria: 1. Patients previously or currently treated with bisphosphonates 2. Soft tissue lesion exposing the underlying bone 3. Persistence of exposed gray-yellowish bone for more than eight weeks 4. Absence of antecedent of radiotherapy in the maxilla and mandible 5. Absence of metastatic zone in the region of osteochemonecrosis The American Association of Oral and maxillofacial surgeons taskforce definition of ONJ is as follows: "the presence of nonhealing exposed bone in the maxilla or mandible that has persisted for more than 8 weeks in a patient who has received a systemic bisphosphonate but has not received local radiation therapy".8 These definitions may be correlated to many hypothesis (Table I, II).

Garcia Saenz and Taruella defined ONJ as the presence of pain, halitosis, soft-tissue swelling, gingival bleeding and infection, with or without dysesthesia of the jaw.21 Today a clear definition is still lacking and needs to be established.

Mechanism of action of amino- and non-aminobisphosphonate and their effect on the biological environment of the jaw Osteochemonecrosis of jawbones represents the main undesirable effect of treatment by nitrogen-containing bisphosphonates, where types used for the treatment of cancer still have to be distinguish from those used for the treatment of osteoporosis.

In cases of osteoporosis, Paget's disease or cancer, bisphosphonates have, since the beginning of prescription, demonstrated many biological effects that, while solving a problem on one hand, will induce osteochemonecrosis of the jaw on the other (Table III).

The mechanism by which bisphosphonates inhibit osteoclast action appears to differ between amino- and non-aminobisphosphonates.

Table I: Complication of ONJ: The most noticed complications of ONJ are: - Aggressive evoluation - Geant sequestrum - Bucco-nasal and cutaneous fistula - Pathological fracture - No concordance between mucosal evolution and bone evolution

Table II: Hypothesis concerning ethiopathology of ONJ: - Hypothesis of hypocellularity and hypovascularization - Infection hypothesis(Actinomyces) - Cytotoxicity hypothesis(Toxicity to keratinocytes of the oral mucosa)

Table III: Biological effect of Bisphosphonates: - Inhibition of soft tissue calcification - Inhibition of bone resorption and therefore reduction in bone remodeling - Anti-inflammatory reaction - Anti-tumor effect - Anti-angiogenic effect ( zoledronic acid+++)

Aminobisphosphonates such as: Zoledronate, ibandronate, risedronate, alendronate and pamidronate, showed to inhibit the Mevalonate pathway by inhibiting the farnesyl-pyrophosphate synthase (acts in synthesizing cholesterol) which will cause apoptosis of osteoclasts (by affecting the biochemical function and morphology of the cell) and reduction in bone remodeling, while the non-aminobisphosphonate such as: Etidronate, Clodronate and Tiludronate, which are non hydrolysable analogues of adenosine triphosphate (ATP), will lead to a lack of ATP inside the osteoclastic cell, causing immediate death of the cell. Bisphosphonates are known to inhibit differentiation of bone marrow precursors into osteoclast, inhibit osteoclast associated to an antiangiogenic effect and increase bone mass by inhibiting the resorption.23 The importance of elucidating the mechanism of action of this complication is to establish a protocol for preventing it.

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Sites of predilection of osteochemonecrosis of the jaw

The majority of reported cases of bisphosphonate-induced osteochemonecrosis of the jaw have been diagnosed after dental procedures such as tooth extraction.9 Some theories noted that bone osteonecrosis correlated to bisphosphonate treatment is silently in evolution and that the act of extraction will reveal it clinically.

In 2006 the American association of periodontology16 (AAP), alerted the risk of developing osteochemonecrosis associated to bisphosphonates: "The Food and Drug Administration (FDA) reclaimed a case of so-called osteonecrosis of the jaw". After the reclamation the number of cases began to increase, particularly in patients treated with intravenous bisphosphonates and who had undergone dental surgery and implant placement.

Herbozo in 2007 showed cases of severe spontaneous bone exposures related to bisphosphonates that were correlated to a decrease in serum VEGF (vascular endothelial growth factor) levels up to 21 days after infusion.32 Osteochemonecrosis may occur spontaneously in patients undergoing bisphosphonate treatment,9 but is more commonly associated with dental surgery.

patients undergoing zoledronic acid treatment.

A study for Merigo and Manfredi15 described the necessity of interruption and replacing intravenous bisphosphonate by non-aminobisphosphonate such as Clodronate. While Marx in 200710 described a study on 17 patients with ONJ where the interruption of Oral bisphosphonate with medical treatment and CTX testing proved to lead to total healing with augmentation of CTX (C-terminal telopeptide) of 26 pg/ml/month with a satisfactory bone remodeling.

The American Association of Oral and Maxillofacial Surgery has published an official paper concerning ONJ. They mentioned that the treatment duration and the route of administration of bisphosphonate have an important role in the proliferation of the lesion. The intravenous form of bisphosphonate is especially concerned but also the oral form associated to invasive dental surgery that can contribute as a risk factor.8 Oral bisphosphonate-induced osteochemonecrosis revealed to be a less severe, less frequent, more predictable and more responsive to treatment entity than intravenous forms of osteochemonecrosis.10 Woo incriminated the zoledronic acid in 35% of ONJ and pamidronate with 31%, the association zoledronate â&#x20AC;&#x201C;pamidronate revealed 28%.20 Brooks in 2007 described two cases of ONJ correlated to a treatment with orally administrated risedronate.12 Fournier and Boissier have shown that pamidronate and zoledronate inhibit angiogenesis, decrease capillary tube formation, and inhibit vascular endothelial growth factor,26 which may constitute an essential cause for bone exposure in this type of bisphosophonate and explains why the exposed bone does not bleed.

A study conducted by Mavrokokki in 2007 noted that the incidence of ONJ obtained in patients treated with intravenous bisphosphonates is 70% following invasive dental treatment and 30% occurred spontaneously. On the other hand, 50% was obtained after surgical treatment in patients undergoing oral bisphosphonate and 50% of ONJ cases were spontaneously obtained.29 In many studies, Zoledronic acid showed to cause delays in wound healing of the tooth extraction socket, inhibit oral epithelial cell migration and promote proliferation and adhesion to hydroxiapatite of oral bacteria without causing osteocyte death neither osteonecrosis of the jaw in mice.30,31

Oral v/s intravenous bisphosphonates

Oral surgery, implantology and bisphosphonates

Risks associated with intravenous therapy appear to be substantially higher than for the oral medications.5 The correlation between bisphosphonate and evolution of ONJ is resumed as: absence of healing of soft tissue in

Although oral bisphosphonate therapy is not considered an absolute contra-indication in patients who require oral surgery, informated consent is important, especially in patients who are still undergoing bisphosphonate treatment

Bone turnover in the mandible is ten times more critical than in the tibia region.17 The rate of alveolar bone turnover at the crest is twice the rate around mandibular canal and five times that of the inferior border of the mandible, which explains why the alveolar bone is the most predictable site for the development of ONJ.17 In cases of spontaneous exposed bone, the most common site involved appears to be the posterior lingual part of the mandible over the mylohyoid ridge area.23 A study conducted by Senel and Duman demonstrated that inflammation of soft tissue and periapical trabecular bone in the posterior mandible is considered the region of predilection for the development of ONJ in patients undergoing zoledronic acid treatment compared to anterior mandible.27 The maxilla and mandible are considered the region of predilection of ONJ due to the oral cavity environment9 and present the highest rate of bone remodeling.

Osteochemonecrosis of the jaw - provoked or spontaneous phenomena

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and necessitating dento-alveolar surgery.

Jeffcoat in 2006 showed no correlation between orally administrated bisphosphonate and implant failure,24 while Savoldelli in 2006 described a case of implant failure due to bisphosphonate-associated osteochemonecrosis of the jaw with bone sequestration in patients undergoing intravenous zoledronic acid treatment.25 Berardi in 2007 described the necessity of covering implants with a layer of non-aminobisphosphonate (Clodronate) that proved to enhance the differentiation of osteoblasts.33 Another study on rabbits by Chacon in 2006 after administration of alendronate showed no effect on osseointegration of implants.34 Hypotheses are still ambiguous and further investigations are needed.

Weak point theory The complete cycle of bone remodeling is 160 days in means of 3 to 4 months in normal cases without bisphosphonate treatment. Thus surgery to be conducted on a patient undergoing bisphosphonate treatment, who has a systemic metabolic condition, should be delayed until the end of the bone remodeling in order to minimize the risk of developing ONJ, due to reduction of bone remodeling and inhibition of bone resorption. The region of bone remodeling will be recognized by bisphosphonates as a weak area which may lead to exposed bone. Bisphosphonates will reduce the rate of bone remodeling and so removal of microdamaged regions of bone may be impaired. Since non-invasive extraction site healing involves osteoclastic and osteoblastic activity to remodel the tooth socket, the action of bisphosphonate in the region with bacterial infested saliva in the socket may result in the alteration of the wound healing and therefore inducing ONJ.

Adjuvant and alternative treatments used nowadays Today many adjuvant therapies are used in order to treat ONJ. A study conducted by Vescovi and Merigo in 200811 on 14 cases, showed the ability of the Nd-YAG laser to enhance the medical and surgical treatment of exposed necrotic bone areas. On the other hand two studies conducted in 2007 by Petrucci14 demonstrated ozone therapy combined with surgical intervention as a possible option with 54% healing rate. This may be due to the antibacterial and healing potentials of ozone therapy. (Table IV).

Some alternative treatments are used nowadays to replace bisphosphonate treatment and prevent ONJ such as: Teliparatide, strontium ranelate (Protelos), Denosumab human monoclonal antibodies.

A study published in 2009 by Anastasilakis,

demonstrated, in cases of osteoporosis, that the use of antibodies specific to the Receptor Activator of Nuclear Receptor Factor-Kappa B (RANKL) inhibitor, Denosumab, can be effective in such pathology in order to replace the usage of bisphosphonate and obtain a satisfactory bone anti-resorption activity.13 Another study published by Body 200635 showed Denosumab to have a fast anti-resorption activity and to have an effect in the prevention of bone complication compared to bisphosphonates prescribed in breast cancer and multiple myeloma cases.

Today the use of antiangiogenic molecules (anti-VEGF) Bevacisumab (Avastin) showed cases of exposed bone that was repaired after interrupting the medication.

More research is still necessary to elucidate these theories.

Recommendations for prevention of osteochemonecrosis Prevention by ensuring adequate oral health before treatment is indicated, particularly if high doses of bisphosphonates are employed.

Recommendations for dental management of patients taking bisphosphonate have developed. Marx in 2007 established some recommendations for the prevention of ONJ (Table V).10 The American Dental Association established some recommendations for the prevention of ONJ by establishing measures to optimize dental health in patients who will be treated with bisphosphonate. Invasive dento-alveolar surgery should be considered cautiously and should be performed with minimal soft and hard tissue trauma, with separate treatment of each sextant. If all 4 sextants are concerned, a waiting period of 2 months is recommended before treatment of the other sextant associated to chlorhexidine 0.12% mouth wash8.

As it is imperative that we establish predictive and preventive dental metrics for prevention of ONJ, accurate examination and treatment planning should be established.

Until more is known, measures should be taken to prevent osteochemonecrosis of the jaw especially in patients who are still undergoing oral and intravenous bisphosphonate treatment.

Guidelines for the treatment of osteochemonecrosis Treatment of osteochemonecrosis may be difficult to achieve and it can be presented by medical or surgical interventions.

Marx does not recommend surgery in treatment of bone osteonecrosis as it will only lead to more exposed bone.10, 28 Marx established a protocol for the treatment of oral bisphosphonate-induced osteonecrosis where he uses a mouth wash with 0,12% chlorhexidine in cases of painless

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Table IV: Adjuvant treatments:

Table VII: Treatment of ONJ according to SISBO recommendations:

- Hyperbaric Oxygenotherapy - Concentrated platelets

- Stage 1:

Interruption of bisphosphonate?

Chlorhexidine 0.12%, norma saline and bicarbonate based mouth wash Control each 15 to 20 days Oral hygiene

- Stage 2:

Antibiotic(Amoxicillin 2g/day associated to Metronidazol 1g/day)for 2 to 3 months Amphotericin B (Fungizone) 80mg daily for 2 to 3 months Chlorhexdine 0.12%, norma saline and bicarbonate mouth wash Minor Analgesic (Tramadol) with antiinflamatory medications (Mefenamic acid) A minimal invasive bone curettage Enoxaparin(Lovenox) ,30mg daily Cholecalciferol (VitD) 5000 UI/day Monadiol(VitK)10mg/day Pentoxifyline 400mg (Vasodilatator) twice daily associated to tocopherol(VitE)1000UI/day for 2 to 3 months PTH(1-34) 400UI/day for 2 weeks Replacement of aminobisphosphonate by clodronate

- Stage 3:

Antibiotic prescribed after culture and study of infested bacterias Amphotericin B(Fungizone) 80mg daily for 2 to 3 months Chlorhexidine 0.12% mouth wash, norma saline and bicarbonate Minor Analgesic (Tramadol) with antiinflamatory medications (Mefenamic acid) PTH(1-34) 400UI/day for 2 weeks Enoxaparin(Lovenox),30 mg daily Pentoxifyline 400mg (Vasodilatator) twice daily associated to tocopherol(VitE)1000UI/day for 2 to 3 months Cholecalciferol (VitD) 5000 UI/day Monadiol(VitK)10mg/day Replacement of aminobisphosphonate by clodronate

- Phototherapy laser ND-YAG - Ozone therapy

Table V: Prevention of ONJ:Marx 2007.10 - Patients diagnosed with osteoporosis and are prescribed a bisphosphonate: Non restorable teeth should be removed, followed by periodontal therapy and a recall schedule.

- Patients who have been taking an oral bisphosphonate and present for dental treatment: If less than 3 years, CTX testing is not necessary, the healing will be uncomplicated.

- If more than 3 years, CTX testing is highly recommended, if more than 150pg/ml oral surgery can be done without complications and a drug holiday with or without a substitute drug approved for osteoporosis can be established.

Table VI: Recommendations for the treatment of ONJ: Longobardi 2007:18 - Surgical treatment like debridement, removing all the osteonecrotic tissue and covering the lesion with sliding flap.

- Pharmacological therapy using antibiotics and chlorhexidine-based mouth wash.

- Hyperbaric therapy.

exposed bone. If the patient reports pain, antibiotic therapy should be prescribed (PenicillinV-K 500mg), 4 times daily for 14 days or when pain is controlled. No surgery of debridement should be conducted in these cases as it will lead to more exposed bone.10 Longobardi in 2007 recommended a management of ONJ using a surgical treatment and indicating that the "not friable limit" represents the clinical limit for debridement (Table VI).18 In cases of osteochemonecrosis Marx noted that the entire bone is affected therefore cannot be debrided.28 Treatment of exposed bone using hyperbaric oxygen therapy may not offer an additional benefit.23

Two treatment modalities exist today: 1. Medical treatment: Can or cannot be associated to the surgical treatment where the surgeon can control the case with adequate medications until he obtains a spontaneous removal of the sequestrum and wound healing with an epithelialization of the underlying soft tissue.

2. Surgical treatment: This consists of eliminating the sequestrum and curettage of affected bone after elevation of

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Case 1

Figure 1: Panoramic radiograph showing empty sockets after spontaneous loss of teeth.

Figure 2: Extraoral vue, showing the fistula circumscribed by granulation tissues.

Figure 3: Panoramic view showing the extended mandibular sequestrum, with fracture of basal bone.

Figure 4: Intraoral view showing the extended bone exposure.

soft tissue flap, the medical treatment will follow.

The evolution will be either "stabilization" with good bone and soft tissue healing or "aggravation" with exposed bone and sequestrum formation. Some measures were established by the SISBO concerning treatment of ONJ cases (Table VII).

The aim of these recommendations is to provide comprehensive care with minimal risk and a satisfying stabilization of the osteochemonecrosis pathology.

Clinical cases according to SISBO recommendations Case 1 A 67 year-old male patient consulted our private clinic, for an asymptomatic bone exposure causing halitosis and difficulty in masticatory functions. The patient mentioned that since starting treatment for osteoporosis 6 months previously, he had experienced spontaneous loss of all his teeth (Figure1). Detailed questioning revealed that was undergoing intravenous bisphosphonate treatment based on zoledronate (Zometa 4mg/month).

An extraoral examination showed a facial asymetry with a fistula draining pus. (Figure 2). The panoramic examination showed an extended sequestrum of the alveolar crest with remaining fractured basal bone (Figure 3). The intraoral examination revealed a yellowish, exposed bone extending from the right to the left molar region (Figure 4). The case was classified as a stage 3 osteochemonecrosis of the jaw related to bisphosphonates.

The patient was operated on under general anesthesia, and the sequestrum was removed (Figure 5). No osteosynthesis device was placed to prevent trauma to the remaining fractured basal bone. A partial flap ensured covering of the remaining bone and Polyglactin 910 ensured stabilization of the mucosa (Figure 6). The fistula pathway was removed and an artificial drainage was placed for 3 weeks (Figure 7). Post operative medication was prescribed.

A 4 months post operative control showed clinically a total healing of the wound and an acceptable jaw function.

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Figure 5: View of the extended mandibular bony sequestrum.

Figure 6: Intraoral view of the wound after removal of sequetrum.

Figure 7: Artificial drainage placed after enucleation of granulation tissue.

Figure 8: 4 months later, a total healing of mucosa was obtained.

Case 2

No extraoral findings were depicted. The SISBO recommendations were prescribed for 2 months. Isolation with mobility of the 38 tooth was obtained followed by removal of the tooth and sequestrum (Figure 13).

2 months later, the patient underwent further chemotherapy treatment, which resulted in recurrent osteochemonecrosis of the jaw in the mandible region. Exposed bone, mobility and fluctuation with localized pain were the evolving symptoms.

The SISBO recommendations were prescribed for another 1 month. After 5 weeks, total healing was obtained with no involvement of vital structures (Figure 14).

A 62 year-old female patient consulted our private clinic for a spontaneous loss of teeth. On intraoral examination, she showed absence of the 35 and 37 teeth, with exposed fluctuant yellowish bone (Figure 9). The patient mentioned irradiated pain in the mandibular bone region, with spontaneous loss of teeth 1 month previously.

After questioning, the patient revealed undergoing zoledronate (Zometa 4mg/ month) treatment intravenously, for the past 8 years, associated to chemotherapy and surgical ablation of the left breast following cancer of the same region. The treatment was interrupted 2 years ago but she was still undergoing chemotherapy every 6 months.

Panoramic and Cone Beam examination detected an osteolytic region in the left mandible region and an intimate contact with the lower alveolar nerve, although no paraesthesia was noticed (Figures 10 - 12). The osteolytic region extended from the 35 to 37 site. The case was classified as a stage 2 osteochemonecrosis of the jaw.

Discussion Bisphosphonates are prescribed to stabilize bone loss caused by osteoporosis and to inhibit the resorption of trabecular bone by osteoclasts in order to preserve its density.

Osteonecrosis is considered as a complication with uncertain prognosis and a low healing rate.

The clinical aspects of the presentation of bone

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Case 2

Figure 10: Panoramic view, showing absence of 1.6, 3.5 and 3.7 teeth with a sequestration of bone in both right maxillary and left mandible regions.

Figure 9: Intraoral view of the yellowish exposed bone in lower left mandible.

Figure 11: Frontal cut of cone beam showing the sequestrum in intimate contact with the lower alveolar nerve.

Figure 12: 3D cone beam radiography showing the amount of bone undergoing sequestration and its contact with lower alveolar nerve.

Figure 13: Macroscopic view of the 7 cm sequestrum after osteochemonecrosis of the lower left alveolar bone, with the extracted 3.8 tooth.

osteochemonecrosis associated with bisphosphonates described in literature are diverse, some very extensive and others limited to the extraction socket.

Typical presentation is a non-healing extraction socket or exposed bone with progression to sequestrum, swelling and purulent discharge.21 The site of predilection of ONJ showed to be the posterior region of the mandible, due to the high rate of remodeling in this region.

Figure 14: Intraoral view 4 months post operatively, note the total healing in the region with absence of exposed bone.

The precautionary measures still include comprehensive interrogation to detect all the existing risk factors.

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Osteochemonecrosis is reported as being a spontaneous and provoked process depending on the molecule used and the existing risk factors such as trauma (tooth extraction).

Some co-morbidity factors should be considered such as corticosteroids, chemotherapy, trauma and infection, when faced with a patient undergoing a bisphosphonate treatment and necessitating a surgical intervention36. Dose cumulated factor which is the dose absorbed modified by the biodisponibility of each bisphosphonate may be another theory determining the predilection of bisphosphonate to cause ONJ. CTX testing showed to be an interesting indicator of recovery of bone remodeling.10 The type of bisphosphonates showed to play an important role in the development of ONJ are associated with pamidronate and zoledronate.20-22, 27 The data demonstrates that the duration of bisphosphonate treatment constitutes a risk factor due to its accumulation in bone.23 The non-aminobisphosphonate (Clodronate) promotes the neoformation of bone seen in peri-implant tissues and stimulates the neoformation of bone around implants compared to other bisphosphonate.33 Surgical debridement of the lesion appreared to lead to more complications and exposed bone with no biological reactivation,18 supporting the theory that ONJ is a silent phenomenon and that surgical intervention will reveal it clinically.

Drug holidays were also found to be insufficient in many ways, as bisphosphonate was found in bone many years later.19 Conservative medical treatment showed to be more efficient in cases of ONJ. Medical treatment of ONJ using Penicillin is recommended due to its wide action, especially if associated to Metronidazole, which will act on anaerobic germs. Some cases can be treated using Quinolone (Ciprofloxacine) due to its bactericide effect, which can be prescribed until the end of clinical symptoms (pain, infection).

Conservative medical therapy with prescription of antibiotics and mouth wash and a non surgical approach is advocated.8 The effect of bisphosphonates is a reduction in bone turnover, resulting in the preservation of the bone mineralization. This treatment can lead to a destruction of osteoclasts with maintenance of osteocytes that are responsible for mineralization of bone. This causes sclerosis of the lamina dura, which is considered a region of predilection for remodeling. Bisphosphonates will be highly concentrated in this region and will be unable to remodel, leading to spontaneous loss of teeth and development of osteochemonecrosis of the jaw. Radiographic changes are not evident in the first stages of ONJ. It has been demonstrated that bisphosphonates inhibit endothelial cell functions and that pamidronate inhibits not

only bone resorption but also bone blood flow.2 We have accumulated some recommendations concerning the treatment of ONJ, and which, based on the clinical cases the SISBO protocol, have so far proved efficient.

Conclusion Osteochemonecrosis of the jaw associated to bisphosphonate is a severe complication for patients undergoing bisphosphonate treatment. Until now no consensus was established for the prevention or treatment of osteochemonecrosis, and the main objective remains the control of pain and inflectional symptoms.

This article supports the need to establish preventive measures in all patients treated with bisphosphonates in order to prevent osteochemonecrosis pathology of the jaws.

It further needs to alert surgeons about the potential complication of maxillary and mandibular bone in patients receiving bisphosphonate therapy with proposing guidelines established by SISBO for the treatment of bone osteochemonecrosis of the jaw.

As more data becomes available, the guidelines will need to be updated.

References 1. Cheng A, Mavrokokki A, Carter G, Stein B. The dental implications of bisphosphonates and bone disease. Aust Dent J 2005; 50: 4-13.

2. Merigo E, Manfredi M. Bone necrosis od the jaws associated with bisphosphonate treatment: a case report of twenty-nine cases. Acta Biomed 2006; 77: 109-117.

3. Kohno N. Treatment of breast cancer with bone metastasis:bisphosphonate treatment â&#x20AC;&#x201C;current and future. Int J Clin Oncol 2008; 13: 18-23.

4. Diel IJ, Fogelman I. Pathophysiology, risk factors and management of bisphosphonate-associated osteonecrosis of the jaw: Is there a diverse relationship of amino- and nonaminobisphosphonates?

Critical Reviews in Oncology/Hematology 2007; 64: 198-207.

5. Grant BT, Amenedo C, Freedman K, Kraut RA. Outcomes of placing dental implants in patients taking Oral Bisphosphonates: A review of 115 cases. J Oral Maxillofac Surg 2008; 66(2): 223-30.

6. Marx RE. Pamidronate(Aredia) and zoledronate(Zometa) induced avascular necrosis of the jaws: a growing epidemic.

J Oral Maxillofac Surg 2003; 61(9): 1115-7.

7. Ruggiero SL, Mehrota B, Rosendberg TJ. Osteonecrosis of the jaws associated with the use of bisphosphonates: a review of 63 cases. J Oral Maxillofac Surg 2004; 62(5): 527-34.

8. American Dental Association council on scientific affairs-

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Dental Management of patients receiving oral bisphosphonate therapy: expert panel recommendations. J Am Dent Assoc 2006; 137(8):1144-50.

9. Ruggiero SL, Fantasia J. Bisphosphonate-related osteonecrosis of the jaw: background and guidelines for diagnosis, staging and management. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006; 15(3): 74-8.

10. Marx RE, Cillo JE, Ulloa JJ. Oral bisphosphonateinduced osteonecrosis:risk factors, prediction of risk using serum CTX testing, prevention and treatment. J Oral Maxillofac Surg 2007; 65(12): 2397-410.

11. Viscovi P., Merigo E. Nd:YAG Laser Biostimulation in the Treatment of Bisphosphonate-Associated Osteonecrosis of the Jaw: Clinical Experience in 28 Cases. Photomedicine and laser surgery 2008; 26(1): 37-46.

12. Brooks J. Osteonecrosis of the jaws associated with the use of risedronate: report of 2 new cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:780-6.

13. Anastasilakis AD. Efficacy and safety of Denosumab in postmenopausal women with osteopenia or osteoporosis: A Systematic Review and a Meta-analysis. Horm Metab Res 2009; 41: 721-729.

14. Petrucci MT. Role of ozone therapy in the treatment of osteonecrosis of the jaws in multiple myeloma patients.

Haematologica 2007; 92(9):1289-90.

15. Merigo E., Manfredi M. Jaw bone necrosis without previous dental extraction associated with the use of bisphosphonates(pamidronate and zoledronate): a four-case report. J Oral Pathol Med 2005; 34(10): 613-7.

16. AAP statement on Bisphosphonates.The American Academy of periodontology web site 2006, http://www.perio.org/resources-products/bisphosphonates.htm.

17. Dixon RB., Tricker ND. Bone turnover in elderly canine mandibles and tibia. J Dent Res 1997; 76: 25-79.

18. Longobardi G. Surgical therapy for osteonecrotic lesions of the jaws in patients in therapy with bisphosphonates. J of Craniofacial surgery 2007; 18(5): 1012-17.

19. Rodan GA. Bisphosphonate: mechanisms of action. J Clin Invest 1996; 97: 2692.

20. Woo SB. Systematic review: Bisphosphonate and osteonecrosis of the jaw. Ann of Int Med 2006; 144(10): 753-61.

21. Garcia Saenz JA, Tarruella SL. Osteonecrosis of the jaw as an adverse bisphosphonate event: Three cases of bone metastatic prostate cancer patients treated with zoledronic acid. Med Oral Patol Oral Chir Buccal 2007; 12: 351-6.

22. Durie BG. Osteonecrosis of the jaw and bisphosphonates. N Engl J Med 2005 ; 353: 99-102.

23. Robinson NA. Bisphosphonates- A word of caution.

Ann Aca Med Singapore 2004; 33: 48-49.

24. Jeffcoat M. Safety of oral bisphosphonates: controlled studies on alveolar bone. Int J Oral Maxillofac Implants 2006; 21(3): 349-53.

25. Salvoldelli C. Ostéonécrose maxillaire sous bisphosphonates et implants dentaires. Revue de stomatologie et de chirurgie maxillo-faciale 2007; 108(6): 555-58.

26. Fournier P, Boissier S.. Bisphosphonates inhibit angiogenisis in vitro and testosterone-stimulated vascular regrowth in the ventral prostate in castrated rats. Cancer Res 2002; 62: 6538.

27. Senel F., Duman M. Jaw bone changes in rats after treatment with zoledronate and pamidronate. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: 385-91.

28. Marx R., Sawarati Y. Bisphosphonate-induced exposed bone(osteonecrosis/osteopetrosis) of the jaws: Risk factors, recognition, prevention and treatment. J Oral Maxillofac Surg 2005; 63: 1567-75.

29. Mavrokokki T, Cheng A. Nature and frequency of bisphosphonate-associated osteonecrosisof the jaws in Australia. J Oral Maxillofac Surg 2007; 65: 415-23.

30. Kobayashi Y, Hiraga T. Zoledronic acid delays wound healing of the tooth extraction socket, inhibits oral epithelial call migration, and promotes proliferation and adhesion to hydroxyapatite of oral bacteria, without causing osteonecrosis of the jaw, in mice. J Bone Miner Metab 2010; 28: 165-175.

31. Huja SS, Fernandez SA. Zoledronic acid decreases bone formation without causing osteocyte death in mice.

Archieves of oral biology 2009; 54: 851-56.

32. Herbozo P., Briones D. Severe spontaneous cases of bisphosphonate-related osteonecrosis of the jaws. J Oral Maxillofac Surg 2007; 65: 1650-1654.

33. Berardi D, Rossi F, Trisi P,Volpi R. Pharmacologic modulation of clodronate in local therapy of periodontal and implant inflammation. Int J of Immunopathol and Pharmacology 2007; 20(1): 69-75.

34. Chacon GE. Effect of alendronate on endosseous implant integration: an in vivo study in rabbits. J Oral Maxillofac Surg 2006; 67(7): 1005-9.

35. Body JJ. A study of the biological receptor activator of nuclear factor-K B ligand inhibitor, denosumab, in patients with multiple myeloma or bone metastases from breast cancer. Clin Cancer Res 2006; 12:1221-1228.

36. BadrosA.Osteonecrosis of the jaw in multiple myeloma patients: clinical features and risk factors. J Clin Oncol 2006; 24: 945.

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CLINICAL

Restoration of endodontic teeth: An engineering perspective Gregori M. Kurtzman1

Introduction Identifying the canals and negotiating them to be able to instrument and obturate the tooth is necessary to clinical success. But restoration of the endodontically treated tooth is critical to long-term success. It does not matter if we can complete the endodontic portion of treatment if the tooth cannot be restored. With this in mind, we need to look at the restoration phase from an engineering perspective. What is needed to reinforce the remaining tooth so that it can manage the repetitive loading that occurs during mastication? This article will discuss the importance of ferrule in adhesive dentistry as well as when to use posts and what materials are best.

Ferrule: How important is it today?

1

Dr Gregori M. Kurtzman is in private general practice in Silver Spring, Md., and a former assistant clinical professor at University of Maryland. He has lectured internationally on the topics of restorative dentistry, endodontics and implant surgery and prosthetics, removable and fixed prosthetics, and periodontics and has over 350 published articles.

He has earned fellowship in the AGD, AAIP, ACD, ICOI, Pierre Fauchard, ADI, mastership in the AGD and ICOI and diplomat status in the ICOI and American Dental Implant Association (ADIA). Kurtzman has been honored to be included in the “Top Leaders in Continuing Education” by Dentistry Today annually since 2006 and was featured on their June 2012 cover. He can be reached at dr_kurtzman@marylandimplants.com

Ferrule was an important concept in dentistry but has been de-emphasized with the bonding evolution. Yet this concept is as important today as it was prior to dental bonding. But what is a ferrule? A ferrule is a band that encircles the external dimension of residual tooth structure, not unlike the metal bands that exist around a barrel to hold the slats together. Sufficient vertical height of tooth structure that will be grasped by the future crown is necessary to allow for a ferrule effect of the future prosthetic crown; it has been shown to significantly reduce the incidence of fracture in the endodontically treated tooth.1,2 Important to this concept is the margin design of the crown preparation, which may include a chamfer or a shoulder preparation. Because a chamfer margin has a bevelled area that is not parallel to the vertical axis of the tooth, it does not properly contribute to ferrule height.

Therefore, when a chamfer is utilized it would require an additional 1mm of height between the edge of the margin and the top aspect of the coronal portion of remaining tooth structure. Thus, use of a chamfer may not be the best margin design when restoring endodontically treated teeth or those teeth with Figure 1: Strain analysis of a posterior tooth significant portions of missing tooth demonstrating concentration of strain on loading structure. With today’s movement toward at the cervical. (Image/Dr Gene McCoy)

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Figure 2: As a maxillary anterior tooth is loaded during mastication, tension and compression occur at the crown’s margins.

(Images/Dr Gregori M. Kurtzman)

Figure 3: Opening of the margin on the tension side may lead in time to recurrent decay or restoration and endodontic failure.

scanning and milling for fixed prosthetics, whether done in the practitioner’s office or at the laboratory, it should be noted that it is difficult to scan the internal aspect of a shoulder preparation and it has been uniformly recommended that a rounded shoulder be used. The rounded shoulder preparation provides the maximum vertical wall at the margin, with the internal aspect being slightly rounded versus at a 90-degree angle. This ensures

better replication of the margins when scanned and milled.

Some studies suggest that while ferrule is certainly desirable, it should not be provided at the expense of the remaining tooth/root structure.3 Alternatively, it has also been shown that the difference between an effective, long-term restoration and restorative failure can be as small as 1mm of additional tooth structure that, when encased by a ferrule, provides greater protection. When such a

Figure 4: Difference of intensity of strain and location related to ferrule height during occlusal loading (Libman).

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Figure 5: Comparison of load distribution of fiber posts compared to a cast post and prefabricated metal post.

long-lasting, functional restoration cannot be predictably created, osseous crown lengthening should be considered to increase what tooth structure is available to achieve a ferrule, but this is also dependent on the periodontal status

of the tooth, and when ferrule cannot be achieved then extraction should be considered.4 Ichim, et al, stated succinctly, “The study confirms that a ferrule increases the mechanical resistance of a post/core/crown restoration.”5

How much ferrule is required?

Figure 6: Tooth restored with a fiber post demonstrating coronal horizontal fracture supracrestally typically seen with teeth restored with fiber posts when overloaded.

When rebuilding an endodontically treated tooth, it is best to maintain all dentin that is available, even thin slivers.

These thin slivers of dentin provide a strong connecting link between the core and tooth’s root and between the crown and root.6 It is important to attempt to retain as much tooth structure as possible, and this aids in achieving ferrule as well as maintaining cervical strength of the tooth where loading concentrates. Under masticatory loading, strain concentrates at the cervical portion of teeth, thus it is important to avoid over-preparation of this portion of the tooth during endodontic treatment and preserve this area during restoration of the tooth (Fig. 1).

Multiple studies discussing how much ferrule is required have found that teeth with at least 2mm of ferrule have significantly greater long-term prognosis from a restorative standpoint then those with less or no ferrule. Libman, et al, reported, “Fatigue loading of cast post and cores with complete crowns of different ferrule designs provide evidence to support the need for at least a 1.5-mm to 2.0-mm ferrule length of a crown preparation. Crown

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preparation with a 0.5-mm and 1.0-mm ferrule failed at a significantly lower number of cycles than the 1.5-mm and 2.0-mm ferrules and control teeth.”7 Libman further demonstrated when loading at an off-axis direction, which occurs in the maxillary anterior, at the restoration’s margin the side where the load is originating is under tension, whereas the opposing side is under compression (Fig. 2).

This repetitive loading and micro strain due to tension at the lingual margin leads to the margin opening, which may lead to recurrent decay and/or failure of the endodontic seal or restoration (Fig. 3).

Additionally, if we look at strain studies by Libman and others comparing ferrule of different heights, we observe that in a ferrule of 0.5mm there is greater strain at the margin under tension and concentrates at mid tooth where the core or post is situated. Teeth with 2.0mm of ferrule demonstrated significantly less strain loading at the margins or centre of the cervical aspect of the tooth. The lower the strain at the cervical midpoint, the less chance of overload and failure restoratively (Fig. 4).

Figure 7: Vertical root fracture of a tooth restored with a metal post.

Do all posts function the same?

Detecting failure at the coronal seal It is not unusual to have a patient present for a routine recall appointment and the clinician or hygienist note recurrent decay at a crown margin with the patient unaware of the issue. This becomes more complicated with teeth that have previously undergone endodontic treatment, as there is no pulp present that could warn the patient an issue is present until often extensive decay occurs or the crown dislodges from the remaining tooth.

Freeman, et al, in their published study, stated, “Fatigue loading of three different post and core designs with the presence of a full cast crown leads to preliminary failure of leakage between the restoration and tooth that is clinically undetectable.”8 The literature supports that coronal leakage may be a major factor in failure of endodontic treatment.9–11 As previously discussed, when loaded during mastication, margins with inadequate ferrule may demonstrate micro opening on the tension side, leading to leakage over time.

This initially may be observed as recurrent decay, but as it deepens and exposure of the obturation material results, failure of the endodontics may result due to apical migration of oral bacteria. This is minimized when a bonded core or post/core is present, but given sufficient time when a ferrule of sufficient height is not present the endodontics or the restoration will fail.

Teeth function differently, depending on the material that the post is fabricated from, with loads distributed within the root relative to the modulus of elasticity of the post compared to the dentin of the root (Fig. 5).

When a tooth restored with a fiber post does fail due to overload, the mode of failure is coronal, protecting remaining root and tooth structure.12 This mode of failure with fiber-post-restored teeth typically allows the tooth to be restored, as vertical root fracture is a rare occurrence. Bitter reported, “Compared to metal posts, FRC posts revealed reduced fracture resistance in vitro, along with a usually restorable failure mode” 13 (Fig. 6). Whereas, with metal posts either prefabricated or cast, failure was at a higher value for cast post and core 91 per cent of the specimens had fractured roots, none of the specimens with a fiber post demonstrated root fracture; the post and core usually fractured at the tooth composite core interface.14 As stress concentrates at the apical tip of the metal post due to its higher modulus of elasticity than the surrounding root, vertical root fracture is a frequent occurrence (Fig. 7). This may result also from breakdown of the cement luting the post to the root, allowing slippage microscopically of the post in the tooth under load, leading to torque at the cervical area and the resulting vertical root fracture.

As metal posts are stiffer (higher modulus of elasticity) than the dentin of the root, with metal posts stress concentrated

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GPa

Comparative Modulus of Elasticity

200

100

Fiber

Dentin

Titanium

Steel

Cast metal

Figure 8: Comparative modulus of elasticity of different post materials.

at the posts apical leading to vertical root fracture and catastrophic loss of the tooth. Ansari reported, “The risk of failure was greater with metal-cast posts (nine out of 98 metal posts failed) than with carbon fiber posts (using which, none out of 97 failed) risk ratio.”15 But with fiber posts having a flexibility equal or greater then the root (lower modulus of elasticity) stress concentrated at the cervical region leading to horizontal fracture of the post and core and typically the tooth can be salvaged.

The elastic modulus refers to the relative rigidity of the material. The stiffer the material, the higher its relative modulus. When two different materials are placed together, as an example, a post is placed into a tooth’s root the elastic modulus is influenced by whichever of the materials is stiffest. Dentin averages a modulus of elasticity of 17.5 (+/-3.8) GPa, with glass fiber posts at 24.4 (+/-3.4) GPa, titanium prefabricated posts at 66.1 (+/-9.6) GPa, prefabricated stainless steel at 108.6 (+/-10.7) GPa and cast high noble gold posts at 53.4 (+/-4.5) GPa. Cast posts fabricated from noble or base metals have higher modulus then high noble alloys and approach stainless-steel prefabricated posts in their relative stiffness. Fiber posts have an elastic modulus that more closely approaches that

of dentin (Fig. 8). The flexural strength of fiber and metal posts was respectively four and seven times higher than root dentin, and there is still debate on whether a post strengthens the tooth. 16,17 The basic purpose of a post is to aid in retention of the core.

The absence of a cervical ferrule has been found to be a determining negative factor, giving rise to considerably higher stress levels within the root. When no ferrule was present, the prefabricated metal post/composite combination generated greater cervical stress than cast post and cores. Yet, the ferrule seemed to cancel the mechanical effect of the reconstruction material on the intensity of the stresses. With a ferrule, the choice of reconstruction material had no impact on the level of cervical stress. The root canal post, the purpose of which is to protect the cervical region, was also shown to be beneficial even with sufficient residual coronal dentin. In the presence of a root canal post, cervical stress levels were lower than when no root canal post was present. Pierrisnard concluded that the higher the elasticity modulus, the lower the stress levels.18 The material the post is fabricated from should have the same modulus of elasticity as the root dentin to distribute the applied forces along the length of the post and the root

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Figure 9: Minimal tooth missing or previously restored following endodontic treatment.

Figure 10: Moderate tooth missing or previously restored following endodontic treatment.

and not concentrate them at the apical tip of the post.

Studies have shown that when components of different rigidity are loaded, the more rigid component is capable of resisting forces without distortion. This stress is concentrated when the post is the stiffer material at the posts apical tip. The less-rigid component fails invariably when a post is used that is stiffer than the root’s dentin.19 Posts with modulus of elasticity significantly greater than that of dentin create stresses at the tooth/cement/post interface, with the possibility of post separation and failure. As repetitive loading occurs on the endodontically restored tooth, the cement eventually fails at the interface between the metal post and root dentin, allowing microslippage of the post. This allows higher stresses to be exerted on the root, leading to vertical root fracture and catastrophic loss of the tooth. The higher modulus (rigidity) of the metallic posts makes it stiff and unable to absorb stresses. In addition, transmission of occlusal and lateral forces through a metallic core and post can concentrate stresses, resulting in the possibility of unfavorable fracture of the root.20 Dentin’s modulus of elasticity is approximately 14 to 18GPa. Fiber posts have modulus that is approximately 9 to 50GPa, depending on the manufacturer of the post. This provides a similarity in elasticity between the fiber post and dentin of the root, allowing post flexion to mimic tooth flexion. The fiber post absorbs and distributes the stresses and thus shows reduced stress transmission to the root.21 The longitudinal arrangement of fibers in the fiber post and the modulus of elasticity of a post that is less than or equal to that of the dentin may redistribute the stress into the tooth and away from the chamfered shoulder to increase the likelihood of failure of the post core/root interface instead of root fractures. When failure does occur due to overloading, failure typically is in the coronal portion, frequently demonstrating fracture of the core at the tooth

Figure 11: Significant tooth missing or previously restored following endodontic treatment.

interface and leaving the possibility of re-restoring the tooth and not catastrophic loss.22 The flexural properties of fiber posts were higher than the metal post and similar to dentin.23 Whereas, pre-fabricated, stainless-steel post exhibited a significantly higher fracture resistance at failure when compared with the fiber posts. The mode of failure of the carbon fiber post was more favorable to the remaining tooth structure when compared with the pre-fabricated stainless steel post and the ceramic post.24 Ceramic posts were introduced prior to fiber posts as a more esthetic alternative to prefabricated metal posts, and, although not widely used today, they are still available.

Modulus of elasticity of ceramic posts is 170–213GPa, which is approximately 15 times that of dentin. As these ceramic posts are too rigid and transmit more stress to the root canal than the fiber posts, which lead to irreversible root damage via vertical root fracture seen with metal posts, their use is not recommended in restoring endodontically treated teeth today.25

Decision making for restoration of endodontically treated teeth Restoration of endodontically treated teeth needs to take an engineering view of how best to reconstruct the remaining tooth for the best long-term survival. With this in mind, the practitioner needs to categorize the tooth based on how much native tooth structure is present following endodontic treatment and how much existing restorative material is currently present in the tooth.

Minimal tooth missing or previously restored: Posterior teeth gain strength when the marginal ridge area and proximal surface is natural tooth structure and has not been restored. Teeth that have undergone endodontic

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for the core followed by a full coverage crown. Posts are often not needed, as the remaining tooth structure at the cusps after crown preparation is sufficient to retain the core and a ferrule can be achieved. A post may be considered in those patients who are bruxers or clenchers or whose occlusion may place higher forces on the restored tooth due to the tooth’s position relative to the occlusal plane. When a ferrule cannot be achieved, the practitioner should consider osseous crown lengthening or forced eruption to improve the ferrule. Inlay restorations should be avoided in endodontically treated teeth because the access created to perform the endodontic treatment weakens the tooth from a cuspal flexure standpoint and the inlay even when bonded may act as a wedge forcing the cusps apart and leading to fracture of the tooth. An onlay restoration may be utilized, and its design should include shoeing of the cusps to limit cuspal flexure.

Figure 12: Multiple fiber posts placed into a molar to lock the core to the remaining tooth structure.

treatment when either occlusal decay was present in the pits and fissures leading to pulpal involvement or a small- to moderate-sized previously placed amalgam or composite restoration is present require conservative restoration (Fig. 9).

These teeth can be restored with removal of the existing restorative material and cleaning the pulp chamber of obturation material including 2 to 3mm of the canal.

Placement of a conventional composite bonded within the tooth provides a good long-term restorative solution to these teeth, and a crown is not needed typically. The access or existing restoration should leave most of the cuspal width present. When the preparation following removal of decay and existing restorative materials invades the width of the cusp leaving half of this tooth structure missing, more extensive restoration is indicated.

Moderate tooth structure missing or previously restored: When the tooth to be restored is missing one or both marginal ridges and these areas have been previously restored or will be restored, placement of a bonded composite will not suffice as the final restoration (Fig. 10).

The marginal ridges provide resistance to cuspal flexure of the tooth, improving its strength. When these are missing, functional loading of the tooth will allow greater cuspal flexure and consequentially a higher chance of fracture under masticatory function. Restoration of these teeth will require a core buildup with optional pins or other retentive elements

Significant tooth structure missing or previously restored: These teeth are a challenge to restore, as they are after removal of the old restorative material and decay ha left significant portions of the tooth needing replacement (Fig. 11). These teeth will require placement of posts to retain the core of the remaining tooth structure. As the purpose of posts is to retain the core, it is recommended that in multi-canal teeth a post be placed into each canal to cross-pin the core to the remaining tooth structure (Fig. 12). Projection of the posts in posterior teeth due to the angulation of the canals leads to convergence of the posts in the coronal portion of the tooth. This locks the core in place and assists in preventing fracture of the post or dislodgement under function that is observed when only a single post is placed. Use of pins may also be considered to assist in retaining the core portion when cusps are missing and as an augment to posts being placed. These teeth require a full coverage crown to limit cuspal flexure under load. As with teeth with moderate missing tooth structure, use of inlays should be avoided as they do not restrict cuspal flexure. An onlay may be used if desired in some cases but should include shoeing the cusps as part of the preparation design to limit cuspal flexure.

Again, when ferrule is not achievable, consider osseous crown lengthening or forced eruption to improve the ferrule.

Conclusion For restoration of endodontically treated teeth, an engineering view is needed to ensure long-term survival.

Ferrule is often overlooked in today’s age of adhesive dentistry, but it is as critical today as it was in the past. Lack of ferrule has been shown to affect survival of the tooth, and

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the literature supports use of 2.0mm of ferrule, which is more critical in maxillary anterior teeth due to the direction of loading during mastication. Additionally, how we restore the remaining tooth plays a role in potential issues in the long term. Metal posts are being used less frequently due to vertical root fractures that can occur when the tooth is overloaded, and the direction has increasingly moved to the use of fiber posts, which mimic the roots modulus of elasticity.

When teeth restored with a fiber post are overloaded, fracture typically occurs in the coronal (supragingival) portion, leaving sufficient tooth remaining to re-restore the tooth. Teeth rarely fail when they are over-engineered, but many fail due to under-engineering.

References 1. Barkhodar RA, Radke R, Abbasi J: Effect of metal collars on resistance of endodontically treated teeth to root fracture.

J Prosthet Dent 61:676, 1989.

2. Galen WW, Muella K.: Restoration of the Endodontically Treated Tooth. In Cohen, S. Burns, RC., editors: Pathways of the Pulp, 10th Edition.

3. Stankiewicz NR, Wilson PR. The ferrule effect: a literature review. Int Endod J, 35:575–581, 2002.

4. Galen WW, Mueller KI: Restoration of the Endodontically Treated Tooth. In Cohen, S. Burns, RC, editors: Pathways of the Pulp, 8th Edition. St. Louis: Mosby, Inc. 2002, page 771.

5. Ichim I, Kuzmanovic DV, Love RM.: A finite element analysis of ferrule design on restoration resistance and distribution of stress within a root. Int Endod J. 2006 Jun;39(6):443–452.

6. Nicholls JI. An engineering approach to the rebuilding of endodontically treated teeth, J Clin Dent, 1:41–44, 1995.

7. Libman WJ, Nicholls JI: Load fatigue of teeth restored with cast posts and cores and complete crowns. Int J Prosthodontics 8:155–161, 1995.

8. Freeman MA, Nicholls JI, Kydd WL, Harrington GW: Leakage associated with load fatigue-induced preliminary failure of full crowns placed over three different post and core systems. J Endod 24:26–32, 1998.

9. Ricucci D, Siqueira JF Jr.: Recurrent apical periodontitis and late endodontic treatment failure related to coronal leakage: a case report. J Endod. 2011 Aug;37(8):1171–5. doi: 10.1016/ j.joen.2011.05.025.

10. De Moor R1, Hommez G.: [The importance of apical and coronal leakage in the success or failure of endodontic treatment].

Rev Belge Med Dent (1984). 2000;55(4):334–344.

11. Sritharan A.: Discuss that the coronal seal is more important than the apical seal for endodontic success. Aust Endod J. 2002

Dec;28(3):112–115.

12. Jimenez MP, et al. Fracture resistance of endodontically treated teeth with fiber composite posts. IADR abstract no. 323, March, 2002.

13. Bitter K Kielbassa AM: Post-endodontic restorations with adhesively luted fiber-reinforced composite post systems: a review. Am J Dent. 2007 Dec;20(6):353–360.

14. Martinez-Insua A, et al. Comparison of the fracture resistances of pulpless teeth restored with a cast post and core or fiber post with a composite core. J Prosthet Dent 80(5), 1998.

15. Al-Ansari A.: Which type of post and core system should you use? Evid Based Dent. 2007;8(2):42.

16. Plotino G, Grande NM, Bedini R, Pameijer CH, Somma F.: Flexural properties of endodontic posts and human root dentin. Dent Mater. 2007 Sep;23(9):1129–35. Epub 2006 Nov 20.

17. Stewardson DA1, Shortall AC, Marquis PM, Lumley PJ.: The flexural properties of endodontic post materials. Dent Mater. 2010 Aug;26(8):730-6. doi: 10.1016/j.dental.2010.03.017. Epub 2010 Apr 21.

18. Pierrisnard L, Bohin F, Renault P, Barquins M.: Corono-radicular reconstruction of pulpless teeth: a mechanical study using finite element analysis. J Prosthet Dent. 2002 Oct; 88(4):442–448.

19. King PA, Setchell DJ. An in vitro evaluation of a prototype Carbon fiber reinforced prefabricated post developed for the restoration of pulpless teeth. J Oral Rehabil 1990;17: 599–609.

20. Purton DG, Chandler NP. Rigidity and retention of root canal posts. Br Dent J 1998;184:294–296.

21. Cormier CJ, Burns DR, Moon P. In vitro comparison of the fracture resistance and failure mode of fiber, ceramic and conventional post system at various stages of restoration.

J Prosthodont 2001;10:26–36.

22. Martínez-Insua A, da Silva L, Rilo B, Santana U. Comparison of the fracture strength of pulpless teeth restored with a cast post and core or carbon fiber post with a composite core.

J Prosthet Dent 1998;80:527–532.

23. Chieruzzi M, Pagano S, Pennacchi M, Lombardo G, D'Errico P, Kenny JM.: Compressive and flexural behaviour of fibre reinforced endodontic posts. J Dent. 2012 Nov;40(11):968–78. doi: 10.1016/j.jdent.2012.08.003. Epub 2012 Aug 21.

24. Padmanabhan P. A comparative evaluation of the fracture resistance of three different pre-fabricated posts in endodontically treated teeth: An in vitro study. J conserve Dent 2010;13:124–128.

25. Maccari PC, Conceição EN, Nunes MF. Fracture resistance of endodontically treated teeth restored with three different prefabricated esthetic posts. J Esthet Restor Dent 2003; 15;25–31.

Reprinted with permission by Roots, 3/2014.

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Making sense of mouth ulceration: part eight Crispian Scully1

This article focuses on the other main vesiculobullous disorders: • Epidermolysis bullosa • Angina bullosa haemorrhagica • Erythema multiforme.

Epidermolysis bullosa Epidermolysis bullosa (EB) can be a genetic or acquired disease: • Hereditary (the most common type): simplex, junctional and dystrophic • Acquired – epidermolysis bullosa acquisita (EBA).

Hereditary EB causes desquamation with lesions mainly over sites of friction or trauma, affecting feet, hands, neck and occasionally knees and elbows.

Oral lesions include: • Microstomia • Ankyloglossia • Trismus • Enamel hypoplasia.

Diagnosis is from family history and biopsy. Management is attention to oral hygiene.

Phenytoin may reduce blistering.

Angina bullosa haemorrhagica Angina bullosa haemorrhagica (ABH) is an uncommon condition where usually solitary bloodfilled blisters – up to 2-3cm diameter – occur in the mouth (Figure 1) and burst to produce an erosion. It is rather like senile purpura but with no extraoral lesions. Seen most commonly on soft palate, in middle-aged or older patients, histology shows sub-epithelial bulla. The cause is unclear but trauma often precipitates and steroid inhalers are implicated in some patients.

The most important aspect is to exclude other causes of blood blisters, such as amyloidosis, bleeding tendencies and pemphigoid. There is no effective treatment: the patient should be reassured and advised simply to break the blisters if they are of concern.

Erythema multiforme

1

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.

Erythema multiforme (EM) is an acute vesiculo-erosive condition usually related to a hypersensitivity reaction, seen mainly in young adults aged between 20 and 40. It is more common in women than men and has a recurrence rate of 37%.

There is a genetic predisposition to EM, which is seen especially in East Asian ethnic groups and association with HLA-DQB1*0301. Precipitating factors may include: • Infections: herpes simplex virus in 70% of recurrent EM (herpes-associated EM). Many other organisms, such as mycoplasmas • Drugs: NSAIDs, allopurinol, anticonvulsants, antimicrobials, antiretrovirals, anti-TNFs. There are strong HLA associations with drugs causing EM, including: – Abacavir and HLA-B*5701 – Allopurinol and HLA-B*5801 – Carbamazepine and HLA-B*1502 in Han Chinese, Thai, Indian and some other Asians, HLA-A*3101 in Caucasians and HLA-B*1511 in Japanese • Immune conditions: immunisations – eg, BCG or hepatitis B • Food additives or chemicals: benzoates, nitrobenzene, perfumes, terpenes.

Infectious agents are the main cause.

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Figure 1: Angina bullosa haemorrhagica

Herpes simplex virus triggers: • EM minor in nearly 100% • EM major in 55%.

Mycoplasma triggers: • EM minor or major.

Drugs are a common cause of erythema multiforme, especially major forms, such as Stevens-Johnson syndrome or toxic epidermal necrolysis.

Erythema multiforme manifests with a variable picture of: • Swollen, blood-stained lips (Figure 2) • Mouth erosions and ulceration, mimicking the other vesiculobullous disorders • Target skin lesions – virtually pathognomonic.

EM can be separated into minor or major forms.

Minor erythema multiforme affects one site only: mouth alone, or skin or other mucosae. Rashes various, but typically ‘iris’ or ‘target’ lesions, or bullae on extremities.

Major erythema multiforme mostly begins one to three weeks after starting a new drug, such as an: • NSAID (oxicam-type), allopurinol, anticonvulsants • Antibiotic; aminopenicillins, antiretrovirals, cephalosporins, quinolones, sulfonamides • Biologics.

It almost invariably involves oral mucosa. Widespread lesions affect skin, eyes, genitals, pharynx, larynx or oesophagus: • Bullous/other rashes • Ocular changes like mucous membrane pemphigoid (dry eyes and symblepharon) • Balanitis, urethritis, vulval ulcers • Pneumonia, arthritis, nephritis or myocarditis.

Extreme forms are Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). SJS and TEN differ by percentage of skin detachment: • SJS: less than 10% of skin – mortality 1-5% • SJS/TEN overlap: 10%-30% of skin • TEN: more than 30% of skin – mortality 25%-30%.

There is no specific diagnostic test. Erythema multiforme is diagnosed from a positive Nikolsky sign and history as well as biopsy to exclude pemphigus.

Management includes removing the precipitant (stop offending drugs; treat infections), and also supportive care of affected mucosae using: • Anaesthetics topically • Antiseptics

Figure 2: Erythema multiforme

• Topical corticosteroids.

Management of erythema multiforme major may also include: • Wound care • Sepsis treatment • Enteral or parenteral nutrition • Fluid – electrolyte balance • Monitoring for urinary retention • Corticosteroids (controversial) • Ciclosporin • Intravenous immunoglobulins • Other modalities: plasmapheresis, anti-TNF biologics, nacetylcysteine

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 life-threatening 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 Elsevier-Churchill Livingstone, Wiley-Blackwell, or Informa/Taylor & Francis – all of whose cooperation is acknowledged and appreciated.

References Gandolfo S, Scully C, Carrozzo M (2006) Oral medicine. 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 9781-4051-9985-8 Scully C, Flint S, Bagan JV, Porter SR, Moos K (2010) Oral and maxillofacial diseases. Informa Healthcare (London and New York). ISBN13: 9780415414944 Scully C, Bagan JV, Carrozzo M, Flaitz C, Gandolfo S (2012) Pocketbook of oral disease. Elsevier, London. ISBN 978-0-702-04649-0 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

Published with permission by Private Dentistry August 2014

60 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 10, NO. 3

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The South African Society of Endodontics & Aesthetic Dentistry

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

Abstract & Poster Submissions now open

Endodontic Excellence at the Apex of Africa SPONSORS

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PRODUCTS

KAVO

KAVO ESTETICA E50 LIFE

COLTENE

AFFINIS HEAVY BODY BLACK EDITION SYSTEM 360

After enjoying world-wide success with the ESTETICA E50 Classic treatment unit for many years, the latest version LIFE upgrade unit is now available from KaVo. Its particular focus is on enhancing treatment unit features which benefit both the patient and dentist. Innovations see a more streamlined patient chair, with optimised soft upholstery in new colours which work well with modern dental white paintwork. Most impressive of all is the latest in chair side imaging, with an upgraded intra oral camera and optional high definition screen for extra high quality patient viewing.

UNIQUE COLOUR CONTRAST, OUTSTANDING READABILITY Following on the success of the recently launched AFFINIS BLACK EDITION 75ml, Coltene announces Affinis BLACK EDITION System 360. The 5:1 cartridge in 380 ml extends the BLACK product line for those who prefer working with dynamic mixing machines.

The combination of AFFINIS heavy body BLACK EDITION and AFFINIS PRECIOUS provides an exceptional colour contrast and excellent readability with the unique silver and gold pigmentation drastically reducing the light scattering effect, improving visual perception of details.

PLANMECA

MORITA

©

ROMEXIS SMILE DESIGN ©

Planmeca’s Romexis Smile Design allows dentists to design new smiles using a simple 2D facial smile photo and intelligent teeth silhouettes. Synonymous with Planmeca the workflow is characterized by its ease-of-use.

Designing a winning smile is a straightforward process taking only minutes and can be done within a few clicks.

Planmeca’s Romexis© Smile Design is a powerful patient education and communication tool allowing your patient to see the proposed treatment outcome in a photo realistic simulation their new smile. Smile Design also provides the dentist a communication path with their laboratory both visually and numerically of the expected treatment outcomes reducing miscommunication errors.

Planmeca Romexis Smile Design is available for Windows and Mac OS. It is sold as a stand alone version, as well as a module for the Planmeca Romexis® all-in-one software. Contact Henry Schein Halas for direct sales for the dealer code to reduce your cost when purchasing online.

SIGNO G10 V2 Morita treatment units are synonymous with high quality, durability and ergonomic design.

Today the changing dental market calls for a cost effective treatment unit option, even from the very best manufacturer.

The Signo G10 boasts an array of features, enhanced by its highly functional design. With LED lighting options for the operating light and instrument lines, plus ergonomic positioning, procedures can be performed with optimal vision and precision. Signo G10’s oversized operator’s tray can accommodate up to 5 customized instruments, including The Dental Advisor’s top rated, Morita TwinPower highspeed handpieces.

The Signo G 10 is now available with normal dentist element or the over the patient element. Offering the highest standards in quality and build, Signo G10 ticks all the boxes right down to the price.

MOCOM

KAVO

H 10 TETHYS DISINFECTOR

ESTETICA E70/E80 VISION

Disinfector with Ultrasonic bath from Mocom Decontamination, washing, disinfection and drying all in one single step, ensuring simpler, faster, more effective workflows. Tethys H10 is the new Hybrid Disinfection Device (H2D) that makes the instrument reconditioning process simple and practical. This innovative device carries out many of the numerous manual tasks typically encountered prior to sterilization, thus reducing personnel workloads. With the Tethys H10 decontamination, washing, disinfection and drying are compacted into one fast automated process.

The KaVo ESTETICA E70/E80 VISION is KaVo's latest innovation for those who want the best available in a dental treatment unit. With the completely new operating concept and the sensitive touch display, the dental unit can be controlled more intuitively than ever before. The self-explanatory control logic, developed specifically to improve dental work flow, allows direct and rapid access to all the important functions for time-saving and smooth treatment processes.

All products available from: HENRY SCHEIN HALAS • Tel: 1300 65 88 22 • www.henryschein.com.au 62 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 10, NO. 3

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PRODUCTS

PLANMECA

SCICAN LTD

SOVEREIGN CLASSIC

OPTIM BLUE

Planmeca has released the Sovereign Classic into Australia. The Classic is a premium unit that offers a unique synergy of clever design and productivity features that facilitates your work throughout the day.

With the launch of OPTIM BLUE, a surface cleaner and disinfectant, SciCan Ltd., – a full spectrum infection control solution provider – brings new optimal level of performance to dental offices.

The Sovereign Classic’s ambidextrous delivery provides an ergonomic solution; comfort and usability are notable features.

Compact and slim, the unit integrates with your imaging technology and offers an ideal adjunct for the advanced imaging or CAD CAM practice.

•Superior cleaning efficacy provides confidence that disinfection will occur

Built with the most advanced infection control systems, periodic cleaning or continuous disinfection – the choice is yours with the systems logically integrated within the Sovereign Classic unit body.

OPTIM BLUE is a balanced, one step cleaner AND disinfectant that surpasses performance of most competitor’s wipes in:

•Strong disinfection capabilities against difficult to kill nonenveloped viruses: Norovirus, Parvovirus, Poliovirus – not all disinfectants kill them!

•Environmentally sustainable and responsible – the active ingredient breaks down into water and oxygen!

•Unique, durable wipe material that stays wet longer and distributes the disinfectant effectively!

GARRISON

PLANMECA

REELMATRIX™ MARGIN ELEVATION BAND

PLANMECA ROMEXIS© 4

Garrison’s ReelMatrix™ Margin Elevation Band allows for proper adaptation and seal of deep margins so that a composite margin elevation can be performed. The deep margin elevation technique is a useful, non-surgical approach to treating deep localized margins. With the ReelMatrix™ Margin Elevation system, the technique has been significantly improved for an easier, faster, and more predictable application. The clinical scenario benefiting from a deep margin elevation: A deep localized margin which makes isolation during delivery difficult and unpredictable. The margin elevation technique allows proper isolation and elevation of the deep margin areas prior to restoring with an indirect partial coverage restoration (inlay or onlay). The Margin Elevation Band comes in a ReelMatrix kit as well as a refill for the ReelMatrix and Tofflemire.

Planmeca’s all-in-one software is now completely renewed. Romexis© was the first dental software to combine 2D and 3D imaging with the complete CAD/CAM workflow and also providing extended connectivity with Planmeca dental equipment.

The new version 4 of the software introduces an improved user interface that will ease the daily workflow of dental professionals around the world.

Available for Apple Mac OS, Microsoft Windows and mobile platforms Planmeca Romexis© 4.0 and mRomexis allows Planmeca products at a dental clinic to work together seamlessly.

PLANMECA

MOCOM

PLANMECA PROSENSOR HD

B FUTURA 28L AND B CLASSIC 28L

New to Planmeca’s premium imaging is the ProSensor© HD intraoral sensor. Supplied with Romexis 2D Software the sensor is fully compatible with Windows and Mac computers.

The Planmeca ProSensor© HD provides outstanding images within a matter of seconds with resolutions of over 20lp/mm. The sensor’s low noise, high contrast images provide superior diagnostic images, whilst the wide dynamic range of the sensor guarantees consistent results.

The versatile ProSensor© HD can be installed into the ProX Intra Oral X-ray or connected to your PC or network via USB or Ethernet.

The B Futura 28L steriliser is specially designed for the most technologically demanding users. It combines outstanding innovation with unprecedented user- friendliness. Its avant-garde systems have been conceived to offer intuitive immediacy, with the modern touch-screen perfectly embodying what we call “evolved simplicity”.

B Classic 28L speeds up workflow: intensive lab testing, top-quality materials and highly practical program features make of this product the new sterilisation industry benchmark.

All 28L Mocom units (Classic & Futura) are suitable for a normal work bench (H X D X W) 500 x 600 x 480 mm weighing 60 Kg. Available in late September.

All products available from: HENRY SCHEIN HALAS • Tel: 1300 65 88 22 • www.henryschein.com.au 64 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 10, NO. 3

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