In-vitro evaluation of the effect of two surface treatment techniques and three adhesive systems on the shear bond strength of aged composite resin repair

Purpose of study: this study assessed the influence of two surface treatment techniques with three different adhesive system on the shear bond strength of repaired aged composite resins. Materials and methods: Ninety composite cylindrical shaped specimens (8mm × 4.5mm) were fabricated from Estilete Sigma Quick shade A2 composite in transparent Teflon mold, polished with 2500 grit carbide paper and kept in distilled water for 24 hours. Subsequently, the samples were aged with thermocycling for 10,000 cycle. Then, the specimens were separated into two main group in relation to surface treatment (each group of 45 samples); diamond bur treatment and air abrasion with 50µ aluminum oxide then each group divided according to the adhesive system with different application protocol into five subgroups (N = 9); total-etch two-step adper single bond 2, self-etch two-step SE clearfill bond and universal G-perimo bond. Following the application of bonding agents, the sample repaired with the same composite type and shade. The initial shear bond strength was measured, and finally values were statistically analyzed. Results: The mean shear bond strength values of the Bur treatment group (14,38±2,34) was found to be significantly higher than that of the air abrasion group (12,29±1,84) and There was a statistically significant difference in shear bond strength MPa between the subgroups (p: 0.000, p <0.05). The shear bond strength values of diamond bur treatment plus universal adhesive sub-group (16.5±0.79) was found to be statistically higher than the other sub-groups and shear bond strength of the total etch adhesive sub-group (11,63±1,52) was found to be statistically significantly lower in Mpa values than the other sub-groups regardless the surface treatment. Conclusion: During aged composite repair procedures, both the surface treatment and adhesive agent application had an effect on the shear bond strength, with the high value of shear bond strength obtained from a combination of bur treatment with G-primo bond or Clearfil SE bond. Keywords: surface treatment, repair of aged composite resins, adhesive systems.