Effects of Different Cavity Designs on Fracture Load of Fiber-reinforced Adhesive Fixed Dental Prostheses in the Anterior Region

Purpose: To evaluate the fracture strength of inlay-retained, surface-retained, and cantilevered fiber-reinforced adhesively fixed dental prostheses (FRA-FDPs) in the anterior region. Materials and Methods: Thirty-two sound human right central incisors and canines were divided into four groups. Test groups were as follows: group 1, both teeth had deep cavity preparation; group 2, both teeth had shallow cavity preparation; group 3, only the canine teeth had deep cavity preparation; group 4, no preparation was made on the abutment teeth. Lateral pontics were restored with FRA-FDPs. All restorations were subjected to fracture loading from the lateral pontic. The restorations were tested in a universal testing machine (LRX Material Testing Machine) with a crosshead speed of 1 mm/min. One-way ANOVA was used for statistical analyses. Fracture modes were examined visually. Results: The highest (667.3 ± 90.4 N) and the lowest (409.3 ± 158.1 N) debonding values were found for groups 4 and 3, respectively. Conclusions: Different preparation designs (inlay-retained, surface-retained) had no significant effect on fracture strength of FRA-FDPs in the anterior region. However, a cantilever design exhibited significantly lower fracture strength. Delamination of the veneering composite was observed as the primary failure type after fracture tests. Keywords: fracture strength, adhesive FDPs, fiber-reinforced composites