Evaluation of Shear Bond Strength of Resin‑bleached Dentine Treated with Azadirachta indica and Diode Laser: An In-vitro Study

Abstract

Aim: This in vitro study evaluated and compared the effects of Azadirachta indica extract and 980-nm diode laser irradiation on the shear bond strength of resin composite to dentine bleached with 37.5% hydrogen peroxide. Materials and Methods: Thirty extracted non-carious human premolars were decoronated and embedded in acrylic resin blocks with the buccal dentinal surfaces exposed. All specimens were bleached with 37.5% hydrogen peroxide and randomly allocated to three groups of 10 specimens each: bleached control without further treatment, Azadirachta indica extract treatment, and diode laser irradiation at 980 nm. Single Bond Universal adhesive and a nano-hybrid composite resin were then applied. Composite build-ups were standardised to 3 mm in height and 2 mm in diameter. Shear bond strength was measured using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analysed using one-way ANOVA followed by Tukey’s post hoc test, with statistical significance set at p < 0.05. Results: Mean shear bond strength was highest in the Azadirachta indica group (43.981 MPa), followed by the diode laser group (38.273 MPa) and the bleached control group (36.159 MPa). The overall difference among groups was statistically significant, and Tukey’s analysis showed significantly greater bond strength for the Azadirachta indica group than for both comparison groups. Conclusion: Under the tested in vitro conditions, Azadirachta indica treatment improved immediate resin–dentine shear bond strength more effectively than diode laser irradiation.