An in vitro investigation comparing methods of minimizing excess luting agent for cement-retained implant-supported fixed partial dentures.

STATEMENT OF PROBLEM: The use of cement-retained implant-supported prostheses is a well-established treatment option. Techniques have been proposed to reduce the amount of residual excess cement (REC) around cement-retained single-implant restorations. However, studies evaluating the effectiveness of such techniques related to cement-retained implant-supported fixed partial dentures (CRISFPDs) are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effectiveness of various cement application techniques for CRISFPDs. MATERIAL AND METHODS: Two implant analogs were placed in the lateral incisor sites in a maxillary, 3D printed cast with 4 missing incisors. Twenty standardized, removable, printed soft-tissue replicas, 40 milled titanium custom abutments, and 20 milled zirconia CRISFPDs were fabricated. Two cement application techniques, the brush on technique (BOT), and the polyvinyl siloxane index (PI) technique were compared. Two cementation techniques, without bib (control) (n=10) and with a polytetrafluoroethylene (PTFE) bib (test) (n=10), were used. A premeasured amount of interim cement was used to cement the CRISFPDs. The CRISFPDs were retrieved after cementation, and standardized photographs of 4 quadrants of each abutment-CRISFPD assembly were made by using a software program that is used to calculate the ratio between the area covered with REC and the total specimen area. The extension of the REC on both the abutment and soft-tissue replica was measured at sites before and after cleaning the REC. A generalized linear mixed-model procedure was used for statistical analysis (α=.05). RESULTS: For cement application, the polyvinyl siloxane (PVS) index technique had significantly less REC than the brush on technique (P<.05). The use of a PTFE bib led to significantly less REC than when no bib was used (P<.05). CONCLUSIONS: The use of the PVS index technique along with a PTFE bib was effective in reducing REC for CRISFPDs.

Use of Implant-Supported Custom Milled Impression Copings to Capture Soft-Tissue Contours and Incisal Guidance.

A technique is presented where a custom milled impression coping is used to replicate the clinically established anterior incisal guidance to the definitive prosthesis when multiple implants are restored in the esthetic zone. A conventional impression is initially made, then the stone cast is scanned, and a digitally designed custom screw-retained, implant-supported interim prosthesis is milled from a polymethylmethacrylate (PMMA) billet. This is aimed to digitally design the pontic areas, contour the gingival soft tissue, and establish an anterior incisal guidance. A custom milled impression coping (CMIC) is then fabricated. The CMIC has contours similar to the contours of the interim prosthesis and is fabricated from a PMMA billet. Titanium inserts are placed in the interim prosthesis and the CMIC. The CMIC is inserted intraorally and used for the final impression by using a custom tray and by following the open tray impression protocol. With the proposed technique, the exact contours of the digitally designed and clinically verified interim prosthesis are used to fabricate the definitive restoration.

Use of Patient's Own Natural Teeth as Part of the Interim Prosthesis on Immediately Placed Single Implants in a Staged Surgical Approach: A Clinical Report.

A technique is described where the tooth's natural crown is used as part of the interim implant supported prosthesis in clinical situations where a tooth with poor prognosis is extracted and an implant is placed immediately after tooth extraction. A preliminary impression is made before tooth extraction, and the exact tooth positioning is assessed in the laboratory as part of the treatment plan. An acrylic resin repositioning jig is fabricated that will guide the clinician in seating and orienting the crown intraorally after implant placement is completed. After the natural tooth is extracted and an implant is immediately placed via guided approach, the extracted natural crown is hollowed and placed on top of an interim abutment. The natural crown is positioned intraorally by using the acrylic resin repositioning jig. The crown is then internally relined and placed as part of the interim implant supported prosthesis. After osseointegration has been confirmed, a definitive prosthesis is placed.