Flexural strength of repaired denture base materials manufactured for the CAD-CAM technique

Abstract

Purpose: To evaluate the flexural properties of repaired poly(methylmethacrylate) (PMMA) denture base materials for computeraided design/computer-aided manufacturing (CAD-CAM) and to compare them with heat-activated polymerized PMMA. Methods: A total of 288 specimens (65 × 10 × 2.5 mm) were prepared using both CAD-CAM and conventional blocks and repaired using autopolymerizing and visible-light polymerizing (VLC) materials. Microwave energy, water storage and hydroflask polymerization were applied as additional post-polymerization cycles after the repair process. The flexural strength (FS) of the specimens was evaluated using the three-point bending test. Data were evaluated statistically using 2-way ANOVA followed by Bonferroni’s correction to determine the significance of differences between the groups (P ≤ 0.05). Results: The FS of the denture base materials for CAD-CAM was significantly higher than that for the heat-activated group (P ≤ 0.05). The FS was significantly highest when microwave energy was used for the postpolymerization cycle. The FS values for all groups repaired with VLC resin were significantly lower than for the autopolymerization group (P ≤ 0.05). Conclusion: The flexural properties of denture base materials for CAD-CAM repaired using autopolymerizing acrylic resins can recover by 50-70%. Additional post-polymerization cycles for autopolymerizing repair resin can be suggested to improve the clinical service properties of repaired dentures.