Abstract
This study aimed to evaluate the microtensile bond strengths of composite and compomer materials repaired in accordance with the manufacturers' recommended protocols. Three methacrylate-based composites [Filtek Z350 XT, Tetric-N-Ceram (TNC), and Spectrum], one compomer-based composite (Compoglass F), and one silorane-based composite (Filtek P90) were used to fabricate 42 composite blocks. Blocks were light-cured in layers of 2.0-mm thickness, and were distributed among three groups: In group 1, cohesive blocks were layered with the same material; in group 2, blocks were subjected to accelerated aging, then wet-ground and repaired with the same material; and, in group 3, blocks were repaired with P90. Each block was sectioned into 10 beams, and each beam was tested for microtensile bond strength. A stereomicroscope was used to evaluate the mode of fracture. For the same-material repair group, Spectrum showed a higher mean value (37.4 MPa), followed by TNC (35.5 MPa), P90 (35.3 MPa), Compoglass (30.9 MPa), and Z350 (26.7 MPa). However, no statistically significant differences were found between the two repair groups except for TNC, which showed lower, but clinically acceptable, bond strength when repaired with P90 (p < 0.0001). All repaired materials showed predominantly adhesive and mixed failures. However, Compoglass showed higher frequency of cohesive failures.