Reparability of two different CAD/CAM polymer materials using a light-cured composite and universal adhesives

Abstract

ObjectiveTo evaluate the reparability of CAD/CAM polymer materials with universal adhesive systems. MethodsEighty blocks of polymethyl methacrylate (PMMA) and eighty blocks of polyoxymethylene (POM) were milled by the manufacturer (7mm of diameter and 4mm height). The top surface of all specimens was abraded with 50μm Al2O3. The 80 specimens of each material were randomly allocated to four experimental groups (n=20) according to the adhesive system used: OptiBond XTR, Futurabond M+, Scotchbond Universal or OptiBond Solo Plus. Each adhesive and the repairing composite resin (GrandioSO) were applied according the manufacturer's instructions. Specimens were stored in distilled water at 37°C for 48h and submitted to shear bond strength (SBS) tests. Fracture surfaces were observed and classified as: adhesive, cohesive or mixed type. SBS data were analysed with 2-way ANOVA and Kruskal–Wallis and Mann–Whitney tests were used to failure mode data (α=0.05). ResultsThe mean SBS yielded with PMMA specimens was significantly (p<0.001) higher than with POM. There were no statistical (p=0.062) differences between adhesive systems. Statistically significant (p<0.001) differences were found between failure mode observed in the two polymeric materials. No cohesive failure was obtained, with the POM specimens having mostly adhesive failures, in contrast with the PMMA with mostly mixed failures. No significant (p=0.925) differences in failure mode were identified between adhesives. ConclusionIt is possible to achieve an adequate adhesion bond to POM and PMMA. SBS values were higher in PMMA specimens than to POM but no differences were found between adhesive systems.