Effect of diode laser and various chemical pretreatments on immediate shear bond strength to bleached enamel: An in vitro study

Abstract Aim: A comparative analysis was undertaken to determine the impact of grape seed extract (GSE), glutaraldehyde, chlorhexidine digluconate, and diode laser irradiation on the immediate bonding performance of composite resin after bleaching. Materials and Methods: A bleaching protocol using 35% hydrogen peroxide gel (Pola Office Bleach, SDI, Australia) was applied to 60 extracted human maxillary central incisors. Following bleaching, the samples were randomly allocated into four groups ( n = 15) based on the pretreatment protocol employed. Group 1 received 5% GSE; Group 2 received 5% GSE followed by 5% glutaraldehyde; Group 3 received 5% GSE followed by 2% chlorhexidine digluconate; and Group 4 was treated with diode laser irradiation. Pretreatment was carried out before etching in Groups 1 and 4 and after etching in Groups 2 and 3. All samples were bonded using a universal adhesive system and restored with standardized cylindrical composite resin build-ups. Shear bond strength testing was carried out using a universal testing machine at a crosshead speed of 0.5 mm/min. Data analysis involved one-way analysis of variance and Tukey’s post hoc test, with the significance level set at P < 0.05. Results: Groups 2 and 4 demonstrated the highest and statistically comparable bond strength values, followed by Group 3. Group 1 exhibited the lowest values. Conclusion: Pretreatment protocols significantly influenced bonding to bleached enamel. The use of GSE combined with glutaraldehyde and diode laser irradiation enhanced immediate bond strength, whereas GSE alone was least effective.