clinical | EXCELLENCE
Full arch implant-supported 12-unit zirconia bridge a first By Sarkis Nalbandian, BDS (Hons), Grad.Dip.Clin.Dent (Oral Implants), M.Clin.Dent. (Prosthodontics) with Brian Lawrence
he dental community is moving towards nonmetal based restorations at an increasing rate with implant dentistry at the forefront of these technological changes. Initially, all-ceramic systems were limited to single anterior teeth, then posterior teeth and then 3-unit bridges closely followed by 6-unit bridges. Now with the advent of customised yttrium stabilised zirconia, we are able to incorporate full arch bridges that, in selected cases, will provide an optimal clinical outcome. This article describes a technique for fabricating a full arch customised yttrium stabilised zirconia bridge that is sintered at 1500oC using the Zirkon Zahn milling system. The long-term proven success of osseointegrated implants is known to depend on bone type, implant position and the design of the superstructures for distributing masticatory and functional loads to the implants. The failure of implant superstructures is typically attributed to fracture of abutments or retaining screws, fracture of occlusal porcelain and fracture of the cantilevered area. Optimal 3-dimensional positioning of the implants allows for a long-term aesthetic and functional outcome of the implant supported prosthesis. The possibilities for the proshetic superstructure are literally endless, however we felt that this case suited the construction of a zirconia framework direct to fixture. The prosthetic design chosen was suited due to optimal implant positioning, alignment and angulation. Problems with this type of restoration are usually a fracture of the veneering porcelain. Therefore, superstructure retrievability and the possibility of future porcelain repair/modification was important.Using zirconia as a framework is a major advantage, as changes in the framework during porcelain firing is non-existent and the bridge can be modified and issued with the same passive fit. This is probably the greatest advantage to both clinician and the technician.
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Figure 1. Preoperative intraoral view of the terminal dentition.
Figure 2. Preoperative Occlusal view. Consequently a direct screw retained full arch zirconia bridgework was constructed to produce an aesthetic and functional fixed prosthesis. Zirconia is a bio-inert material and exhibits some translucency and a high flexural strength due to high crystal density.
Case study The method described in this report was used to treat a 52-year-old patient referred for surgical implant placement and final prosthetic reconstruction. The patient presented with a terminal dentition (Figures 1 and 2), was a smoker and had bone loss affected by advanced chronic periodontitis; apart from this, healthy with no known allergies.
May/June 2007
clinical | EXCELLENCE
Figure 3. Post operative occlusal view of osseointegrated implants. Optimal implant positioning for direct screw access.
Figure 4. Impression copings in place before splinting and impressions.
Figure 5. Occlusal view of mounted maxillary model.
Figure 6. Milled zirconia framework with direct screw access to the fixture before initial try-in and fit at fixture surface.
Figure 7. The Milled framework is fitted and verified with X-rays. A new MMR is taken.
Figure 8. Fitted framework in place labial view.
Figures 9-12. In position in the milling machine; Pre-Sintering; Post-Sintering; and the Zirkon Zahn milling system.
Figure 14. The direct composite (Vitalescence-Ultradent, Gunz Dental) built up is transferred to the laboratory and the Technician has live view of the smile dynamics.
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Figure 13. The direct composite build-up developed in my practice on the framework helps the clinician to establish ideal aesthetics, speech etc. Patient is able to see the future result and comment. Although this does take time, it saves considerable guesswork for both clinician and technician. No diagnostic wax up or any other diagnostics comes close to this!
Figure 15. Full smile initial mock up as assessed and approved by the patient. Although patient had a moderate smile line, consideration was given to artificial gingival architecture using pink porcelain for an overall aesthetic outcome.
May/June 2007
clinical | EXCELLENCE
Figures 16 and 17. Final 12 - unit zirconia bridgework direct to fixture head.
Figures 18 and 19. Fitting surfaces of the six zirconia abutments.
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clinical | EXCELLENCE
Figures 20 and 21. Final Bridgework in Situ. The pink porcelain adaptation to the abutments and edentulous areas has been created for optimal oral hygiene. The abutment screws are torqued at 35 Ncm.
Figure 22. Panoramic X-ray of final maxillary restoration in situ.
Figure 23. Initial issue of final zirconia framework based bridgework as per direct composite mock up during try in stage of the zirconia framework, removing the guessing by the technician who has produced an exceptional quality of craftsmanship.
Figures 24 and 25. One month in function post-op. The lower arch full implant supported bridgework is to follow in the near future. The treatment plan comprised proceeding with maxillary clearance and immediate implant placement with provisional abutments and bridgework to provide temporary support, comfort, function and aesthetics. The treatment of the maxillary arch is presented here with lower arch reconstruction to be completed in the near future. The surgical procedure was as follows: immediate placement of six fixtures (Nobel Direct, Nobel Biocare) in the maxilla at sites 15, 14, 13, 22, 24, 25 with excellent primary stability being obtained. Provisional abutments were used to house provisional bridgework. Three months later final impressions were taken at cor-
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rect MMR for construction of zirconia framework and final bridgework. Figures 2 to 26 on the following pages document each stage of the case.
Figure 26. Final issue one month postop. One picture says it all!
About the authors
and has lectured on areas of prosthodontics and implant surgery. He has placed and restored over 1000 implants to date. He is in a private referral-based practice in Sydney, limited to Aesthetics, Prosthodontics and Implant Surgery.
Sarkis Nalbandian completed his Bachelor of Dental surgery with honours at Sydney University in 1983 and completed a Graduate Diploma in Clinical Dentistry (Oral Implants) in year 2000. He completed his Masters in Prosthodontics in 2005 with Distinction at King’s College, University of London. Dr Nalbandian is a member of numerous professional organizations both locally and internationally
Brian Lawrence has been a dental technician for 30 years. After travelling and working around the world with a number of master technicians such as Willi Gellar and Thomas Schmidt, he settled in Sydney where he has worked with all forms of ceramic restorations. He is one of the pioneers of milling Zirconia in Australia. Milled abutments and frameworks are his specialty.
May/June 2007