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Compendium July/Aug 2015, Volume 36, Issue 7

Published by AEGIS Communications

A Complex Implant-Supported Reconstruction with Monolithic-Minimally Veneered Zirconia: A Clinical Report Michael Moscovitch, DDS, C.AG.S

Abstract: The purpose of this case report is to highlight the issues of treating a complex maxillary and mandibular fixed, implantsupported reconstruction. It discusses the use of established evidencebased information along with recently developed supporting digital technologies for diagnostics and laboratory procedures, combined with highstrength zirconia ceramic and acrylic materials (polymethyl methacrylate) for provisionals and prototypes. These developments have created an accurate and precise workflow to provide reliable longterm performance and esthetic outcomes without the associated prevalence of damage and wear with previously used restorative materials.

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Implant dentistry has evolved to enable high levels of clinical performance outcomes.1 The development of reliable implants with advanced designs to enhance soft and hardtissue response as well as supporting stable prosthetic applications has created a myriad of choices in implant restorative applications.2 In conjunction with these developments, many new approaches in the management and enhancement of bone and soft tissue have added a dynamic adjunct to implant therapy. The plethora of options available to clinicians for implant selection and placement, abutment connections, soft and hardtissue enhancements, restorative materials, and designs of implant prostheses has become somewhat enigmatic for assembling all of the appropriate components for longterm success.

This report will address many of the current concerns in managing a complex maxillary and mandibular implantsupported reconstruction. The article will explore the rationale for implant selection and timing of placement, loading protocols, and workflows for provisional restorations, prototypes, and definitive prosthesis design with the use of an advanced highstrength zirconia ceramic.

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Clinical Conditions In 2011, a 66yearold male patient presented in good general health with an ailing maxillary porcelainfusedtometal (PFM) segmented reconstruction supported by teeth and implants and a failing mandibular PFM splinted reconstruction supported by teeth. These were completed in 1994 in Paris. The original maxillary reconstruction consisted of six external hex implants in positions Nos. 4 (5 mm), 5 (3.75 mm), 7 (3.75 mm), 10 (3.75 mm), 12 (3.75 mm), and 13 (3.75 mm). Teeth Nos. 6, 8, 9, and 11 were maintained via endodontic treatment. This PFM reconstruction was designed as follows: Two threeunit implantsupported splinted sections: the first, Nos. 5 and 4 (screwedretained abutments), No. 3 pontic; the second, Nos. 12 and 13 (screwedretained abutments), No. 14 pontic.

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http://www.dentalaegis.com/cced/2015/07/AComplexImplantSupportedReconstructionwithMonolithicMinimallyVeneeredZirconiaAClinicalReport

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A Complex ImplantSupported Reconstruction with MonolithicMinimally Veneered Zirconia: A Clinical Report dentalAEGIS.com Two single implantsupported restorations in positions No. 7 (cementretained abutment) and No. 10 (screwretained abutment). Nos. 6 and 11 toothsupported single crowns, Nos. 8 and 9 toothsupported splinted crowns. The original mandibular PFM reconstruction was a 10unit splinted periodontal prosthesis supported by six teeth (endodontically treated): Nos. 20 through 22 and 27 through 29. Nos. 23 through 26 were pontics. In 1999, implant No. 13 failed. This resulted in retreatment of the implant section Nos. 12 through 14 as follows: implant No. 12 retained, implant No. 13 replaced (3.75 mm), and an additional implant placed in No. 14 (5 mm), both external hex implants. The new prosthesis was a threeunit PFM splinted segment with three screwretained abutments. In 2011, the clinical conditions of the above reconstructions were as follows: In the maxilla, the implants were still clinically stable, however the bone levels on implants Nos. 10, 12, 13, and 14 exhibited typical diminished bone levels generally associated with older external hex implants. No. 11 was fractured below the gingival level and the crown was not present. Teeth Nos. 8 and 9 exhibited redecay at the crown margins. In the mandible, the remaining six abutment teeth exhibited 50%plus bone loss. No. 27 exhibited extensive redecay below the crown margin. Parafunctional wear patterns were noted on the occlusal surfaces of the maxillary and mandibular restorations. In past decades, the practice of keeping clinically sound teeth in the same arch as implants was a common treatment approach. Although this made good clinical sense in the early days of implant therapy, it was proven that over time

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this approach created complications in longterm maintenance.3 The patient’s desire was to undertake retreatment to achieve a predictable fixed prosthetic solution for both maxillary and mandibular arches and to avoid having to wear any removable interim or definitive prostheses. The rationale for this approach was important to the patient due to frequent public speaking commitments. This demand created the need to carefully treatment plan the reconstruction to allow for the use of fixed provisionals during the entire treatment period. Fortunately, the remaining natural teeth in both the maxillary and mandibular arches could be strategically retained during treatment so that additional implants could be sequentially placed and loaded allowing for the transition from the existing implant toothsupported situation in the maxilla to a totally implantsupported definitive restoration. As well, the mandibular teeth were able to support a fixed provisional, while implants were placed in strategic positions to allow for the transition from toothsupported to a fully implant supported definitive restoration. The prosthetic workflow was managed with the aid of digital laboratory technologies in the production of the provisional restorations, prototypes, and subsequent definitive monolithicminimally veneered zirconia maxillary and mandibular reconstruction. Zirconia has recently been shown to be an extremely reliable material for implant reconstructions due its favorable properties.4,5 Dental zirconia restorations are produced by milling. This procedure is amenable to computeraided design/computeraided manufacturing (CAD/CAM) technology and its associated precision and accuracy. This allows for continuity of the design incorporated in the provisionals to be easily transferred through to a prototype, which after minor adjustments of function and esthetics, becomes the definitive blueprint for the milling of the monolithic minimally veneered (facial porcelain Nos. 6 through 11 not in function) zirconia

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restorations.6,7

Clinical Workflow After initial consultation, the preoperative fullmouth radiographs were obtained from the referring periodontist (Figure 1). To address the immediate concern of the patient, replacement of the original crown on tooth No. 11 was provisionally secured to the supporting root. Diagnostic study casts were made of the existing clinical conditions (Figure 2). A complete dental and medical assessment and identification and explanation of treatment objectives was performed. The patient was referred back to the periodontist for confirmation of the implant and periodontal treatment proposals. This included a conebeam computed tomography (CBCT) scan of the mandible (Figure 3) to aid in optimal implant placement.8 This was then coordinated with the development of the prosthetic sequencing and design. After presentation of the completed treatment plan to the patient, informed consent was obtained.

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A Complex ImplantSupported Reconstruction with MonolithicMinimally Veneered Zirconia: A Clinical Report dentalAEGIS.com The study casts were used to develop a diagnostic wax mockup of the proposed prosthetic design.9 This information was then transferred to a digital environment for refinement of design and milling of the first set of maxillary and mandibular provisional restorations (Figure 4 and Figure 5).10 The maxillary 12unit provisional restoration (Nos. 3 through 14) was placed as follows: Teeth Nos. 6, 8, 9, and 11 were prepared to the gingival level to allow for these units to be pontics, and then the provisional was secured to the screwretained abutments on existing implants Nos. 4, 5, 10, 12, 13, and 14 and the cementretained abutment on No. 7. No. 3 was left as a cantilevered pontic. The mandibular 10unit provisional restoration (Nos. 20 through 29) was placed as follows: Teeth Nos. 20 through 22 and 27 through 29 were modified to eliminate decay, and composite cores were placed. Teeth Nos. 23 through 26 were left as pontics. The periodontist placed additional implants in the maxilla and mandible and selective extractions as follows: Phase 1—Maxilla: extraction of remaining roots Nos. 6, 8, 9, and 11; placement of internal conical implants in positions Nos. 6 (4.5 mm x 15 mm) and 11 (4.5 mm x 15 mm). This completed the surgical phase of the maxillary reconstruction. The existing provisional was adapted to the new conditions and initially supported by the original implants as described above. Implants Nos. 6 and 11 were left unloaded until full integration, at which time screw retained abutments were installed. The definitive maxillary bridge would be supported by the existing and newly placed implants (nine) with positions Nos. 3, 8, and 9 as pontics. Phase 2—Mandible: extraction of teeth Nos. 28, 27, and 21; placement of internal conical implants in positions Nos. 31 (4.5 mm x 9 mm), 30 (4.5 mm x 11 mm), 28 (5 mm x 11 mm), 27 (4.5 mm x 15 mm), 24 (3 mm x 15 mm), 21 (4.5 mm x 13 mm), 19 mm (4.5 mm x 9 mm), and 18 (4.5 mm x 9 mm). The existing provisional was adapted to the new conditions and supported by remaining teeth Nos. 29, 22, and 20 and immediately loaded implants Nos. 28, 27, 21, and 19 (screwretained abutments) (Figure 6). Phase 3—Mandible: extraction of teeth Nos. 29, 22, and 20; placement of internal conical implant in position No. 22 (4.5 mm x 17 mm). This completed the surgical phase of the mandibular reconstruction. The existing provisional was adapted to the new conditions and supported by the previously placed implants and Nos. 30 (screwretained abutment) and 24 (cementretained). At this time, abutments were installed on implants Nos. 31 and 18 (screwretained) but not loaded. After appropriate healing time, an abutment was installed on implant No. 22 (screwretained). The definitive mandibular bridge would be supported by all of the above implants (nine) with Nos. 29, 26, 25, 23, and 20 as pontics. Upon completion of the above procedures, alginate impressions were made of the provisionals. Polyvinylsiloxane closedtray transfer impressions were made of the maxillary and mandibular arches. The bite registration was obtained by transferring the provisionals to the master casts and mounted on an appropriate articulator. The provisionals and master casts were scanned into the digital environment for production of the maxillary and mandibular prototypes. The prototypes offer the advantage of being able to digitally correct minor design issues and then verifying and adjusting intraorally (Figure 7 through Figure 10). The maxillary prototype was adjusted, polished, and left to function with the mandibular provisional. The definitive maxillary zirconia restoration was then completed from the information provided by the prototype, and the cutbacks for the facial porcelain (Nos. 6 through 11) were done after milling but before sintering. Subsequently, the mandibular prototype was adjusted to the sintered and colored maxillary zirconia framework before the application of porcelain to Nos. 6 through 11 and final glazing (Figure 11). Following this step, the mandibular definitive monolithic zirconia restoration was milled, colored, and sintered. The facial porcelain (Nos. 6 through 11) was applied, and then both maxillary and mandibular restorations were stained and glazed (Figure 12). Both bridges were inserted at the same time (Figure 13 through Figure 15). Minor occlusal adjustments and oral hygiene access was verified and the zirconia surfaces polished. The bridge screws were torqued to 20 Ncm according to the manufacturer’s recommendation, and No. 24 was luted with a provisional cement. Postoperative radiographs were taken (Figure 16). After a period of 1 month, all conditions were reverified and adjusted as needed. The screw access channels were then sealed with polytetrafluoroethylene tape (white) and composite.11 The patient has been followed for continuing care since completion of the reconstruction and no complications have been reported to date (Figure 17 through Figure 20).

Discussion Treating complex implant reconstructions, especially with zirconia, is challenging even when all conditions are favorable.12,13 The task of retreatment of older external hex implants can be associated with unpredictable performance issues with regards to their ability to maintain bone support and prosthetic stability to levels that are expected with newer implant systems.14,15 Therefore, assessment of these older implants with regards to tissue and bone stability must be carefully evaluated before proceeding. Informed consent should include the possibility of future problems that may occur with maintaining osseointegration and subsequent intervention. This condition is becoming more prevalent in older implant cases due to the large volume of patients who were treated over the past decades. These patients are generally in good health, living longer, and many require upgrading of their damaged and worn restorations and ailing and failing implants and/or teeth. This places restorative dentists in a possible tenuous situation to accept full responsibility of performance outcomes of previous treatment without an understanding by the patient. In this case, the aforementioned conditions were possibly present in the remaining maxillary implants as described above and this was carefully explained to the patient. The additional implants (two) that were placed in the maxilla and the new implants (nine) placed in the mandible were a more current system that has documentation supporting more


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A Complex ImplantSupported Reconstruction with MonolithicMinimally Veneered Zirconia: A Clinical Report dentalAEGIS.com stable bone and softtissue levels over time.16 Immediately loading selected implants and remaining teeth in the mandible as described above with a fullarch splinted fixed provisional is an extensively documented technique.17 This approach avoids the use of a removable mandibular transitional denture and the associated sequelae. The digital restorative workflow combining polymethyl methacrylate (PMMA) blocks for the provisionals, prototypes, and zirconia has been shown to reduce clinical treatment time and result in greater accuracy and precision as well as enable the ability to store the associated digital files for future use.4 Zirconia has been shown to exhibit superior biologic characteristics with respect to soft and hard tissue,18 superior strength,19 stability,20, 21 and the avoidance of damage,4 wear,22 and allergic response.23 All patients exhibit varying degrees of parafunctional occlusal activity 24 but are not required to wear an acrylic (PMMA) protective appliance to protect the performance of zirconia restorations with respect to chipping, cracking, and breakage.4

Conclusion Complex implant reconstructions have traditionally been challenging due to variable conditions with respect to soft and hard tissues and recreating functional and esthetic demands. The advent of diagnostic and laboratory digital technologies and materials, especially zirconia, has prompted a new era in predictable, reliable, and stable prosthodontic outcomes for dental patients.

Acknowledgments The author would like to thank Hiam Keren, MDT, for the laboratory support in the production of the restorations in this report; Marvin Werbitt, DDS, periodontist; and Danae Sandoval for the technical assistance in the preparation of this manuscript.

About the Author Michael Moscovitch DDS, C.AG.S (Prosthodontist) Assistant Clinical Professor Department of Restorative Sciences/Biomaterials Goldman School of Dental Medicine Boston University Boston, Massachusetts Lecturer Faculty of Dentistry, McGill University Montreal, Quebec, Canada Dental Residency Program Jewish General Hospital Montreal, Quebec, Canada

References 1. Dhima M, Paulusova V, Lohse C, et al. Practicebased evidence from 29year outcome analysis of management of the edentulous jaw using osseointegrated dental implants. J Prosthodont. 2014;23(3):173181. 2. Taylor TD, Agar JR. Twenty years of progress in implant prosthodontics. J Prosthet Dent. 2002;88(1):8995. 3. Lang NP, Berglundh T, HeitzMayfield LJ, et al. Consensus statements and recommended clinical procedures regarding implant survival and complications. Int J Oral Maxillofac Implants. 2004;19(suppl):150154. 4. Moscovitch M. Consecutive case series of monolithic and minimally veneered zirconia restorations on teeth and implants: up to 68 months. Int J Periodontics Restorative Dent. 2015;35(3):315323. 5. Ilie N, Stawarczyk B. Quantification of the amount of blue light passing through monolithic zirconia with respect to thickness and polymerization conditions. J Prosthet Dent. 2015;113(2):114121. 6. Moscovitch MS. Monolithic zirconia fixed prostheses. In: Beumer J, Faulkner RF, Shah KC, Moy PK, eds. Fundamentals of Implant Dentistry, Volume 1: Prosthodontic Principles. Hanover Park, IL: Quintessence Publishing. 2015:94101. 7. Moscovitch MS, Saba S. The use of a provisional restoration in implant dentistry: a clinical report. Int J Oral Maxillofac Implants. 1996;11(3):395399. 8. Harris D, Horner K, Gröndahl K, et al. E.A.O. guidelines for the use of diagnostic imaging in implant dentistry 2011. A consensus workshop organized by the European Association for Osseointegration at the Medical University of Warsaw. Clin Oral Implants Res. 2012;23(11):12431253. 9. Cho SH, Schaefer O, Thompson GA, Guentsch A. Comparison of accuracy and reproducibility of casts made by digital and conventional methods. J Prosthet Dent. 2015;113(4):310315. 10. Güth JF, Almeida E Silva JS, Beuer FF, Edelhoff D. Enhancing the predictability of complex rehabilitation with a removable CAD/CAMfabricated longterm provisional prosthesis: a clinical report. J Prosthet Dent. 2012;107(1):16.


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A Complex ImplantSupported Reconstruction with MonolithicMinimally Veneered Zirconia: A Clinical Report dentalAEGIS.com 11. Moráguez OD, Belser UC. The use of polytetrafluoroethylene tape for the management of screw access channels in implantsupported prostheses. J Prosthet Dent. 2010;103(3):189191. 12. RojasVizcaya F. Full zirconia fixed detachable implantretained restorations manufactured from monolithic zirconia: clinical report after two years in service. J Prosthodont. 2011;20(7):570576. 13. Walton TR. Making sense of complication reporting associated with fixed dental prostheses. Int J Prosthodont. 2014;27(2):114118. 14. Goodacre CJ, Bernal G, Rungcharassaeng K, Kan JY. Clinical complications with implants and implant prostheses. J Prosthet Dent. 2003;90(2):121132. 15. Ravald N, Dahlgren S, Teiwik A, Gröndahl K. Longterm evaluation of Astra Tech and Brånemark implants in patients treated with fullarch bridges. Results after 1215 years. Clin Oral Implants Res. 2013;24(10):11441151. 16. Eckert SE. Platform switching and clinical science. Int J Oral Maxillofac Implants. 2011;26(2):229232. 17. PeñarrochaOltra D, Covani U, Peñarrocha M, PeñarrochaDiago M. Immediate versus conventional loading with fixed fullarch prostheses in mandibles with failing dentition: a prospective controlled study. Int J Oral Maxillofac Implants. 2015;30(2):427434. 18. Hisbergues M, Vendeville S, Vendeville P. Zirconia: Established facts and perspectives for a biomaterial in dental implantology. J Biomed Mater Res B Appl Biomater. 2009;88(2):519529. 19. White SN, Miklus VG, McLaren EA, et al. Flexural strength of a layered zirconia and porcelain dental allceramic system. J Prosthet Dent. 2005;94(2):125131. 20. Alghazzawi TF, Lemons J, Liu PR, et al. Influence of lowtemperature environmental exposure on the mechanical properties and structural stability of dental zirconia. J Prosthodont. 2012;21(5):363369. 21. Flinn BD, deGroot DA, Mancl LA, Raigrodski AJ. Accelerated aging characteristics of three yttriastabilized tetragonal zirconia polycrystalline dental materials. J Prosthet Dent. 2012;108(4):223230. 22. Park JH, Park S, Lee K, et al. Antagonist wear of three CAD/CAM anatomic contour zirconia ceramics. J Prosthet Dent. 2014;111(1):2029. 23. GökçenRöhlig B, Saruhanoglu A, Cifter ED, Evlioglu G. Applicability of zirconia dental prostheses for metal allergy patients. Int J Prosthodont. 2010;23(6):562565. 24. Klasser GD, Greene CS, Lavigne GJ. Oral appliances and the management of sleep bruxism in adults: a century of clinical applications and search for mechanisms. Int J Prosthodont. 2010;23(5):453462

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