Silica-Nylon Reinforcement Effect on the Fracture Load and Stress Distribution of a Resin-Bonded Partial Dental Prosthesis

Abstract

This study investigated the influence of silica-nylon reinforcement on the stress distribution and fracture load of a resin-bonded fixed partial dental prosthesis (RBFDP). Three-unit RBFDPs (N = 60) were inserted between the first premolar and the first molar of a maxillary model. The groups were divided according to the nylon reinforcement (n = 20/group): conventional fixed prosthesis (without reinforcement), prosthesis with silica-nylon reinforcement positioned vertically, and prosthesis with silica-nylon reinforcement positioned horizontally. Half of the specimens were tested after 24 hours in a universal testing machine until fracture (1,000 kgf; 1 mm/minute) to determine the single load to fracture. The other half was submitted to mechanical aging during 10(6) cycles (100 N, 2 Hz), totaling 6 groups (n = 10/group). The results were analyzed by two-way analysis of variance (ANOVA; alpha = 5%). The stress distribution for non-aged groups was simulated using finite element analysis. The numeric prostheses were modeled similarly to the in vitro assay. ANOVA showed no statistical difference between groups (P<.05) for load to fracture. However, the use of the reinforcement provided stability even after the failure, as the parts did not separate. The computational analysis showed similar biomechanical behavior among the groups. The use of the nylon reinforcement does not influence the fracture load or the stress distribution, but it does enable the prosthesis to remain in position after failure.