In-Vitro Load-Bearing Capacity of Polymethylmethacrylate(PMMA) Resin Long-Term Provisional Fixed-Partial-Dentures(FPDs)

Objectives: The aim of the current study was to investigate the load-bearing capacity of four-unit long-term provisional fixed partial dentures (FPDs) fabricated from polymethylmethacrylate (PMMA) resin for conventional fabrication and for CAD/CAM milling.
Methods: 3 groups (each group, n=10) of four-unit FPDs with identical anatomy were fabricated. The groups were allocated as follows: group TL FPDs were fabricated from Telio Lab, a conventional unfilled PMMA resin, group TC from Telio CAD, a CAD/CAM unfilled PMMA resin, and group VT from Vita CAD-Temp, a CAD/CAM microfiller-reinforced-polyacrylic PMMA resin. All FPDs were subjected to an artificial aging by thermocycling with 10,000 cycles (5°C and 55°C), and then cemented on polyurethane models. All FPDs underwent load testing in a universal testing machine until fracture, which was defined by a reduction in force of 10 N. The fracture lines were visually inspected. The mean loads at fracture for the groups were compared using one-way ANOVA and Dunnett T3 post-hoc test.
Results: The highest mean load at fracture was found in group TC (521.3±161.8 N), followed by group VT (379.8±54.7 N), and then group TL (211.2±18.4 N). The mean loads at fracture in group TC and group VT were statistically significantly higher than group TL (p<0.05). The mean loads at fracture of group TC and group VT were not statistically significantly different from each other (p>0.05). Fracture lines in all groups were detected in the connector between 25 and 26.
Conclusions: CAD/CAM fabricated PMMA provisional FPDs presented a higher load-bearing capacity compared to their conventionally fabricated counterparts and thus may be the preferred fabrication method for long-term provisional FPDs. In the current study, micro-filler reinforcement of the PMMA resin for CAD/CAM fabrication FPDs did not seem to enhance the load bearing capacity of the milled FPDs.