An In-vitro evaluation of effectiveness of diode laser on the shear bond strengthof nanohybrid composite resin to dentin

Introduction: To assess the effect of diode laser on the shear bond strength (SBS) of nanohybrid composite to dentin. Material and Methods: Forty-two extracted mandibular molars (n=42) were selected and sectioned to expose flat dentin surfaces using a diamond bur under constant water irrigation. Specimens were randomly assigned into three groups (n = 14 each). Group 1 (control) self-etch adhesive application. Group 2 self-etch adhesive followed by diode laser irradiation. Group 3 was treated with diode laser irradiation prior to self-etch adhesive application. All samples were restored with nanohybrid composite resin, light-cured, and then subjected to Shear Bond Strength (SBS) testing using a Universal Testing Machine (UTM). The resulting data were statistically analyzed using One-way Analysis of Variance (ANOVA) and Post hoc Tukey’s test, with the significance level set at p < 0.05. Results: Group 2 exhibited highest mean SBS (28.01 MPa), indicating enhanced bond strength. Group 1 showed a moderate mean SBS of 22.29 MPa, while Group 3 recorded the lowest SBS (20.36 MPa). Conclusion: Diode laser application following the self-etch adhesive significantly improved bond strength to dentin. This suggests that timing of laser irradiation plays a crucial role in optimizing adhesive performance. The results support the compatibility of diode laser treatment with self-etch adhesives without compromising bonding efficacy. Key Words: Diode laser; Nanohybrid composite resin; Self-etch adhesive; Shear bond strength; Universal testing machine