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 (microTBS) of multi-mode dentin bonding agents to dentin. 48 premolars were assigned to six groups to determine the microTBS (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 degrees C), the microTBS test was performed at 0.5 mm/min. Data were analyzed by two-way ANOVA and post-hoc Tukey's tests (alpha = 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 (x 40) to determine the failure mode. The microTBS was significantly higher in the laser groups (P < 0.05). The maximum and minimum microTBS 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 degrees C) was lower than the temperature rise during adhesive and composite light curing (4.1 degrees C and 7.5 degrees C, respectively). Irradiation of unpolymerized universal adhesive systems with 810 nm diode laser with 1 W power for 10 s increased the microTBS of composite to dentin.