Objectives: The repair of resin composites may hold clinical advantage. The purpose of this study was to compare the repaired microtensile bond strength of aged silorane resin composite using different surface treatments and either silorane or methacrylate resins. Methods: Silorane blocks (Filtek LS) were fabricated and aged by thermocycling between 8oC and 48oC (5000 cycles). A control (solid composite) and four surface treatment groups (no treatment, acid treatment, aluminium oxide sandblasting and diamond bur abrasion) were tested. Each treatment group was randomly divided in half and repaired with either silorane composite (LS adhesive) or methacrylate composite (Filtek Z250/Single Bond Plus). N was 12 blocks and 108 beams per group. After 24 hours in 37oC water, microtensile bond strength testing was performed using a non-trimming technique. Fracture surfaces were examined using an optical microscope (20X) to determine failure mode. Data was analyzed using Weibull-distribution survival analysis. Results: Results are provided in the table.
Group | Min | Max | Mean (SE) MPa | Weibull Characteristic Strength | Weibull Modulus |
No treatment-Methacrylate | 0.5 | 73.9 | 40.8 (1.9) | 45.3 | 3.0 |
No treatment-Silorane | 13.1 | 66.8 | 37.2 (1.6) | 41.0 | 4.2 |
H2PO4-Methacrylate | 10.6 | 77.5 | 44.1 (1.8) | 48.6 | 4.0 |
Acidic primer-Silorane | 3.8 | 73.1 | 37.3 (2.0) | 41.5 | 2.6 |
Sandblast-Methacrylate | 17.6 | 64.9 | 47.8 (1.5) | 51.3 | 6.6 |
Sandblast-Silorane | 18.0 | 90.0 | 50.2 (1.6) | 54.0 | 6.3 |
Diamond-Methacrylate | 14.4 | 59.3 | 37.7 (1.6) | 41.6 | 4.4 |
Diamond-Silorane | 11.9 | 64.3 | 39.0 (1.7) | 43.2 | 4.0 |
Control | 38.7 | 90.6 | 62.6 (1.6) | 66.7 | 8.0 |
Sandblasting followed by silorane or methacrylate composites and acid treatment with methacrylate composite provided insignificant differences from the control (p>0.05). All other groups were significantly lower than the control. Failure was primarily adhesive in all groups. Conclusion: Sandblasting produced the most acceptable repair bond strengths of aged silorane resin composite using either a silorane or a methacrylate composite. Partial funding and materials support provided by Delta Dental Foundation and 3M ESPE.