Effects of implant supported fixed prostheses and removable partial dentures on prognosis of teeth adjacent to partial edentulous spaces

Purpose: The aim of this retrospective study was to compare the five-year survival and complication-free rates of the teeth adjacent to partial edentulous spaces of implant-supported fixed prostheses (ISFP) and removable partial dentures (RPD). Methods: The subjects were patients with ISFP or RPD inserted from 2003 to 2011 at the Clinic of Removable Prosthodontics, Hokkaido University Hospital. Patients who had complete dentures or an observation period of less than one year were excluded. The variables of the subjects were gender, age, prostheses, and number of remaining teeth. Variables of the adjacent teeth were the types of teeth, endodontic therapy, state of tooth restoration, and the presence of opposing teeth. The outcomes of this study were tooth extraction and tooth complications. Tooth complications were defined as tooth fracture, loss of retention, caries, periapical disease and periodontal disease. The five-year survival and complication-free rates of the adjacent teeth were estimated by Kaplan-Meier analysis. Differences of these rates for the prostheses were evaluated using the log-rank test (α=0.05). Results: In total, 501 patients (ISFP: n=41, RPD: n=460) were selected. The five-year survival rates of the teeth adjacent to the partial edentulous spaces in the ISFP group and the RPD group were 97.5% and 90.9%, respectively. There was no significant difference between the two groups. However, the five-year complication-free rate was significantly higher in the ISFP group (89.3%) than in the RPD group (70.5%). Conclusions: The results of this retrospective study suggested that the prognoses of the teeth adjacent to partial edentulous spaces were influenced by the prostheses.