Effects of 810 nm diode laser irradiation on the micro tensile bond strength of uncured multi-mode dentin bonding agents.

This study aimed to evaluate the effect of 810 nm diode laser irradiation on the microtensile bond strength (µTBS) of multi-mode dentin bonding agents to dentin. 48 premolars were assigned to six groups to determine the µTBS (n = 16). In the control groups, universal adhesives namely Scotchbond Universal, G-Premio, and Ambar Universal were used on dentin. In the experimental groups diode laser (810 nm,1W power) was irradiated for 10 s on unpolymerized adhesive. The adhesive was light-cured and the tooth was restored with composite. After 500 thermal cycles (5-55 °C), the µTBS test was performed at 0.5 mm/min. Data were analyzed by two-way ANOVA and post-hoc Tukey's tests (α = 0.05). One extra tooth per group was used to assess the thermal changes during the light-curing on dentin, laser irradiation, adhesive and composite light curing. Six additional teeth were used to assess the micro-morphology of the resin-dentin interface by scanning electron microscopy (SEM). Specimens were evaluated under a stereomicroscope (× 40) to determine the failure mode. The µTBS was significantly higher in the laser groups (P < 0.05). The maximum and minimum µTBS were recorded in G-Premio + laser (GBL) (19.91 ± 3.0 Mpa) and Ambar Universal + laser (ABL)(11.71 ± 3.0 Mpa) groups, respectively. The dominant failure mode was adhesive in the control groups and mixed in the laser groups. The temperature rise during laser irradiation (2.2 °C) was lower than the temperature rise during adhesive and composite light curing (4.1 °C and 7.5 °C, respectively). Irradiation of unpolymerized universal adhesive systems with 810 nm diode laser with 1 W power for 10 s increased the µTBS of composite to dentin.