DTIN0210

DeNtaltribuNe|april-June, 2010 technology 23 Fig. 1: Pre-treatment intra-oral frontal view: A large space was noted between the intaglio surface of the prosthesis and the maxillary tissue, and there was significant tissue resorption on the labial surface of the implant over the maxillary right canine area. The patient was asymptomatic. Fig. 2: Full-thickness flap revealed the advanced bone loss on the labial surface of the implant. In spite of the tissue damage, this implant was clinically firm. Fig. 3: Maxillary prosthesis before the application of tooth-colored porcelain; excessive crown length was noted at this stage. Fig. 4: Completed maxillary prosthesis with gingi- val-colored porcelain applied to provide adequate lip support; excessive crown height was reduced. Fig. 5: Anterior view showing the CAD/CAM-- fabricated full-ceramic implant abutments at the approximated vertical dimension of occlusion. Fig.6:Occlusalviewofthemaxillaryarch beforein- sertion of the maxillary prosthesis; favorable ante- rior-posterior spread allowed the replacement of posterior teeth with distal cantilevering. Fig. 7: Completed maxillary implant-supported prosthesis;notetheplacementofthesupra-gingival margins. were reported. Sub-optimal maxillary lip support was noted. A significant amount of dead space was identified between the intaglio surface of the pros- thesis & the maxillary soft tissue. Upon removal of the maxil- lary prosthesis, all the maxillary implants were found to be osseo- in-tegrated. The patient desired to correct the failing implant, restore lip support, masticatory function and facial esthetics. The overall treatment plan- included removal of the implant at the maxillary right canine area, replacement of a new implant at the maxillary right canine region and fabrication of a full-arch, zirconium oxide- based ceramic restoration in the maxilla. Under local anaesthesia, the implant at the maxillary right canine area was removed surgi- cally (Fig. 2) and a new 13 mm long regular platform implant was placed (NobelReplace, Ta- pered Groovy). The new implant was submerged and primary wound closure achieved. The existing prosthesis was reinser- ted during the healing period to serve as a provisional prosthesis. Once osseointegration was achieved a few months later, the new implant was exposed and the maxilla was ready for pros- thodontic rehabilitation after a few weeks of soft-tissue healing. Six implant-level impression copings (NobelReplace) were placed onto the maxillary impla- nts. High-viscosity vinyl polysi- loxane material (Aquasil Ultra Heavy, DENTSPLY DeTrey) was carefully injected around all the impression copings. A stock tray loaded with putty material (Aquasil Putty, DENTSPLY De Trey) was seated over the entire maxillary arch to make the definitive impression. A jaw-relation record at the treatment vertical dimension was made with a vinyl poly- siloxane material (Regisil PB, DENTSPLY DeTrey). The maxillary and mandi- bular definitive casts were mounted arbitrarily in the center of a semi-adjustable articulator (Hanau Wide-vue, Teledyne Waterpik) using aver- age settings.17,18 The custom zirconium oxide abutments with gold-alloy fitting surface (Procera, Nobel Bio- care) were CAD/CAM fabricated according to the prosthesis design. The development of the planned definitive maxillary restoration was carried out using a CAD/CAM process. The maxillary definitive cast with the custom full-ceramic abutments were scanned (Zeno Scan, Wie- land Dental+Technik), and the prosthesis framework was desi- gned using a software program (D700, 3Shape). The framework was milled in zirconium-base-material (Zeno Zr Bridge, Wieland Dental + Technik) with a milling machine (Zeno 4030 M1, Wieland Dental+ Technik). The prosthesis frame- work was sintered according to the manufacturer’s recom- mendations. Subsequently, overlaying low -fusing, tooth-colored porcelain material (IPS e.max, Ivoclar Vivadent) was manually applied onto the exterior to create pro- per anatomic form (Fig. 3). Low-fusing, gingival-colored porcelain material (IPS e.max) was applied to create proper lip support (Fig. 4). During the delivery clinical session, the old prosthesis was removed and the new custom abutments were torqued to 32 Ncm (Fig. 5). The new prosthesis was tried in to verify color, occlusion, lip support, teeth form and comfort. Upon confirmation of the patient’sacceptance,theimplant abutments were sealed in gutta- percha (Fig. 6) and the pros- thesis was cemented in resin- modified glass-ionomer luting agent (RelyX Unicem, 3M ESPE). The patient was evaluated 2 weeks postoperatively. Anterior guided occlusal schemes were verified intra-orally before and- after prosthesis cementation (Fig. 7). The patient reported no discomfort and she had been functioning well with the new resto-rations. No abnormal clinical signs were noted. Discussion Osseointegration is a well- documented and predictable clinical treatment option. On the other hand, management of implant-failure is also a clinical reality. In this clinical report, the failure of one implant at a crucial location indicated the need for re-fabrication of the entire implant prosthesis. As the patient desired a high level of esthetics, full-ceramic restorations were selected. By prescribing tooth-colored ce- ramic abutments & full-ceramic restorations, prosthesis margins were made at the gingival level and gingival retraction proce- dures were eliminated during impression and prosthesis insertion. Full-arch prosthodontic re- habilitation using fixed pros- theses usually requires longer- term provisional restoration in order to facilitate a predictable treatment outcome. In this patient, the existing maxillary prosthesis served as a long-term provisional resto- ration for verifying her adapt- ability, & multiple professional clinical adjustments of provi- sional restorations were not required. This treatment sequence increased the margin of safety in the execution of the definitive full-ceramic restoration. Intra-oral verification of the new treatment occlusal scheme and detailed in situ clinical adjustment of the restorations on the day of prostheses inser- tion still formed the essential foundation for proper treatment execution. In any major prosthodontic treatment, the patient should be informed of the potential financial and time implications should the need for refabrication of the restorations arise. Conclusion The functional management of an edentulous maxilla using a full-ceramic implant-supported maxillary prosthesis has been- reported. New CAD/CAM-based restorative materials were used in treating this case. The use of high-strength full-ceramic restorations enha- nces overall esthetic predicta- bility and long-term functional outcome. A complete list of references isavailablefromthepublisher. DT About the author Dr. Ansgar C. Cheng is a pros- thodontist with Specialist Dental Group™, Mount Elizabeth Hos- pital, Singapore, and an adjunct associate professor at the Na- tional University of Singapore. Dr. Ansgar C. Cheng 3 Mount Elizabeth #08-10 Singapore 228510 Republic of Singapore E-mail: drcheng@specialist dentalgroup.com