Fiber-reinforced composite fixed dental prostheses with various pontics

To evaluate the load-bearing capacities of fiber-reinforced composite (FRC) fixed dental prostheses (FDP) with pontics of various materials and thicknesses.

Inlay preparations for retaining FDPs were made in a polymer phantom model. Seventy-two FDPs with frameworks made of continuous unidirectional glass fibers (everStick C&B) were fabricated. Three different pontic materials were used: glass ceramics, polymer denture teeth, and composite resin. The FDPs were divided into 3 categories based on the occlusal thicknesses of the pontics (2.5 mm, 3.2 mm, and 4.0 mm). The framework's vertical positioning varied respectively. Each pontic material category contained 3 groups (n = 8/group). In group 1, pontics were fabricated conventionally with composite resin (G-ӕnial, GC) with one additional transversal fiber reinforcement. In group 2, the pontics were polymer denture teeth (Heraeus- Kulzer). Group 3 had an IPS-Empress CAD pontic (Ivoclar Vivadent) milled using a Cerec CAD/CAM unit. Groups 1 and 2 served as controls. Each FDP was statically loaded from the pontic until initial fracture (IF) and final fracture (FF). Initial-fracture data were collected from the load-deflection graph.

ANOVA indicated statistically significant differences between the materials and occlusal thicknesses (p < 0.001). Quadratic analysis demonstrated the highest correlation between the thickness of the pontic and IF and FF values with ceramic pontics (IF: p < 0.001; R2 = 0.880; FF: p < 0.001; R2 = 0.953).

By increasing the occlusal thickness of the pontic, the load-bearing capacity of the FRC FDPs may be increased. The highest load-bearing capacity was obtained with 4.0 mm thickness in the ceramic pontic. However, with thinner pontics, polymer denture teeth and composite pontics resulted in higher load-bearing values.