Transverse strength of acrylic denture base resin repaired with different mechanical surface treatment methods

Objective: The aim of this study was to investigate the effects of different mechanical surface treatment methods on the transverse strength of a repaired conventional heat-polymerized acrylic resin. Materials and Method: One hundred and sixty rectangular-shaped acrylic resin specimens were prepared using a custom mold, and divided into 4 groups according to different surface treatment methods; Group 1 (control): no treatment, Group 2: air-borne particle abrasion, Group 3: plasma application, and Group 4: Er:YAG laser application. Following the surface treatments, the repaired surfaces were examined using Scanning Electron Microscopy (SEM) and Energy Dispersion Spectroscopy (EDS). Then, the specimens were repaired with autopolymerizing acrylic resin to form a total of 80 (n=20/group) rectangular-shaped (65×10×3.3 mm) test specimens. The repaired specimens were subjected to thermal cycling. Then, the transverse strength was measured by a three-point bending test using a universal testing machine. The data were analyzed by using one-way ANOVA and Tukey HSD tests. The results were considered significant for α=0.05. Results: Group 2 (27.06 ± 5.02 MPa) and Group 4 (26.06 ± 3.44 MPa) revealed significantly greater transverse strength values compared to the control (Group 1; 18.26 ± 5.27 MPa), and Group 3 (11.19 ± 2.73 MPa) (p<0.05), Group 3 revealed significantly lower transverse strength values compared to all other groups (p<0.05). Conclusion: Air-borne particle abrasion or Er:YAG laser application increased the transverse strength of heat-cure acrylic resin repaired with autopolymerizing acrylic resin; however, the plasma treatment decreased the transverse strength.