Effect of laser applications with different agents on dentin surface roughness, bacterial adhesion and tubule occlusion.

Objective: This study aimed to evaluate the effects of laser application with different agents on dentin surface roughness, tubule occlusion, and bacterial adhesion in vitro.

Materials and methods: A total of 216 dentin blocks from bovine incisors were divided into nine groups. Treatments included 5% sodium fluoride (NaF) varnish, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), Er, Cr: YSGG laser, and diode laser in various combinations. Surface roughness (SR) was measured using a profilometer. S. mutans and S. mitis suspensions were incubated for 24 h, and bacterial adhesion was quantified (×10⁸ Cfu/ml) and visualized using confocal laser scanning microscopy. Tubule occlusion was assessed via SEM imaging and analyzed with ImageJ software. Statistical analysis was performed using one-way ANOVA and Tukey HSD (p = 0.05).

Results: Except for the CPP-ACP groups treated with laser, all groups exhibited significantly higher surface roughness (p < 0.05); however, this did not influence bacterial adhesion (p > 0.05). All treatments significantly reduced the number and diameter of open dentinal tubules (p < 0.05). The combination of NaF with Er, Cr: YSGG and diode laser enhanced tubule occlusion, while CPP-ACP with laser had no additional effect.

Conclusions: Increased surface roughness, except in CPP-ACP with laser groups, did not affect bacterial adhesion. All desensitization methods effectively promoted tubule occlusion, with the diode laser demonstrating greater efficacy than the Er, Cr: YSGG laser.

Clinical significance: Lasers should be used with caution as they may increase the roughness of the dentin surface. The combined application of NaF with lasers may improve its clinical efficacy.