Statement of problem: There is no known data on the functional efficacy of different removable partial denture designs.
Purpose: This randomized clinical trial compared the masticatory performance of two commonly used designs in 118 patients who needed a unilateral or bilateral mandibular partial denture.
Material and methods: One half of the patients received a partial denture with distal occlusal rests and cast circumferential clasps and the other half a partial denture with mesial rests and I-bar cast clasps. The left side, right side, and swallowing threshold masticatory tests were made with peanuts and carrots before treatment and 16 weeks after the prosthesis insertion (baseline) and thereafter at 6, 18, 36, and 60 months.
Results: Masticatory scores at entry were higher in the circumferential design group, but the only significant (p < 0.05) difference was found in the right side carrot performance. Both groups realized significant improvements (p < 0.001) in all performance scores with partial dentures. Mean improvements of 24.7 with peanuts and 35.8 with carrots in the right side performance scores and 19.0 in the swallowing threshold score with peanuts in the bar design group were significantly higher (p = 0.017) than the respective mean improvements of 15.9, 21.4, and 5.6 in the circumferential design group. However, no significant differences were found between the two groups for any of the 10 performance scores at baseline.
Conclusions: Despite some performance differences at entry, the mean performance scores for the two groups became similar at baseline and at subsequent intervals.