The Efficacy of Different Surface Treatments in Composite-Composite Bond Strength

Objectives: This study aimed to investigate the most effective method in increasing composite-composite bond strength in the clinical repair procedures.
Methods: A total of 224 composite (Clearfil Majesty ES-2) disks (5 mm x 3.5 mm) were prepared and stored in 37^°C distilled water for 24h. The samples were randomly divided into two groups as aged and non-aged. Aged group samples were subjected to 20,000 thermal cycles. All aged and non-aged groups were divided into five different subgroups including different kinds of surface treatments (control without any surface treatment, 38% orthophosphoric acid (OA), Al₂O₃ sand-blasting (SB) with and without adhesive resin (AR) application). After these surface treatments, additional composite disks, 2 mm in diameter, were bonded to the previously prepared composite samples. Failure forces (N) were recorded with a shear bond tester (BISCO, Schaumburg, IL, USA) to then calculate the shear bond strength values (failure force divided to the bonded area). Data collected (in megapascals) were subjected to two-way ANOVA and Tukey’s test (P=0.05).
Results: Adhesive resin application increased the bond strength of the study groups. OA alone decreased bond strengths in aged and non-aged groups. In both non-aged and aged groups, the highest bond strength values were received with the SB groups (P<0.05).
Conclusions: The results of this study showed that the most effective surface treatment for composite-composite bond repair was sandblasting and adhesive resin application together.