Effect of Er: YAG laser on repair bond strength of a nano-hybrid composite

Introduction: advancements adhesion technology, invasive approaches popularity in today’s dentistry. their aesthetic and mechanical properties, composite materials are widely used in clinical practice. Objectives: This study aimed to evaluate whether surface pre-treatment with Er: YAG laser and bur, and application of various universal adhesives is effective on the repair bond strength of thermally aged nano-hybrid composite restorations. Material and methods: A total of 96 disc-shaped specimens were made from a nano-hybrid resin composite material (Clearfil Majesty Esthetic, Kuraray), using standard size (14 mm diameter × 2 mm thickness) silicon molds. Thermally aged composite disc specimens were assigned randomly into 2 equal groups according to pre-treatment methods (bur or Er: YAG laser). Then, specimens were divided into 3 sub-groups according to used universal adhesive: GPB (G-Premio BOND, GC), CUB (CLEARFIL™ Universal Bond, Kuraray), and ABU (All-Bond Universal, Bisco, Inc.). They were aged 5,000 thermocycles and subjected to a shear bond strength test. Data were analyzed statistically, with p = 0.05. Results: The groups that received pre-treated with Er: YAG laser showed statistically higher values of bond strength than the groups pre-treated with burs ( p < 0.05). There was no statistically significant difference between the groups pre-treated with Er: YAG laser. For the groups pre-treated with bur, there were no statistically significant differences between B-CUB (Bur/Clearfil Universal Bond) and B-ABU (Bur/All-Bond Universal) groups ( p > 0.05). B-GPB (Bur/G-Premio Bond) group exhibited the lowest bond strength ( p < 0.05). Conclusions: Er: YAG lasers may be used as alternative method used for pre-treatment for repairing nanohybrid composite restorations. Silane-containing universal adhesives do not have better repair bond strength than other universal adhesives.