Maintenance of Implant-Supported Maxillary Prostheses: A 2-year Controlled Clinical Trial

Purpose: To analyze maintenance service of fixed maxillary prostheses and overdentures based on conventional gold bars or titanium bars and frameworks fabricated with computer-aided design/computer-assisted manufacture (CAD/CAM) technology. Materials and Methods: Forty-one patients participated; 16 received an implant overdenture with a gold bar (gold OD), 12 received a CAD/CAM-fabricated implant OD with a titanium bar (Ti OD), and 13 received a CAD/CAM implant-supported fixed prosthesis (IFP). The bars and frameworks were screw-retained at the implant level. Maintenance service performed during the first 2 years was recorded and compared between the three groups. After this 2-year period, the Oral Health Impact Profile (OHIP) was administered. Results: For ODs (gold, Ti) most service consisted of activation of the matrices. Fractures of matrices and bar extensions occurred only in the gold OD group, and 65% of these patients exhibited hyperplasia of the peri-implant mucosa. The maintenance rates were 1.24 (gold OD), 1.36 (Ti OD), and 0.98 (IFP). These differences were not statistically significant. Retightening of occlusal screws was not necessary in any group. The probability that a complication occurred in the first year was high (60% to 70%) and statistically not different between the three groups. The probability that a second complication occurred was significantly lower for the IFP group versus the gold OD group. The mean OHIP values were 1.7 (IFP), 6.7 (gold OD), and 7.3 (Ti OD); ratings in the IFP group were significantly better. Conclusions: Maintenance service was typical for implant prostheses in the edentulous maxilla. Direct screw retention at the implant level without abutments had a favorable effect in all groups. A trend toward a reduction in problems was observed with the CAD/CAM superstructures. The OHIP confirmed high satisfaction, but quality of life appeared to be slightly higher with fixed prostheses. Keywords: computer-aided design/computer-assisted manufacture, edentulous maxilla, fixed prosthesis, overdenture, prosthetic maintenance