Impact of a high-power 810 nm diode laser on intra-dentinal decontamination, dual-species biofilm reduction, and smear layer removal: an ex vivo study.

The purpose of this research was to evaluate the impact of an 810 nm high-power diode laser on decontaminating both surface and intradentinal biofilm, as well as removing the smear layer. Forty human mandibular premolars were contaminated with a biofilm composed of Enterococcus faecalis and Streptococcus mutans. The teeth were divided into groups and treated with NaOCl 2.5% + PUI, saline solution + 810 nm laser, NaOCl 2.5% + PUI + 810 nm laser, and a control group. The samples were then evaluated using a confocal laser scanning microscope (CLSM). Another 40 teeth, prepared as dentin discs, were contaminated with the same biofilm to assess surface decontamination. Additionally, 80 bovine dentin discs with an induced smear layer, placed in the apical third of mesial root canals of 3D-printed teeth, underwent similar treatments. Pre- and post-treatment images were obtained using an environmental scanning electron microscope. Data were statistically analyzed with ANOVA test and Tukey's test, respectively. Intradentinal disinfection rates were 67,33% for PUI, 51,50% for the 810 nm laser, and 55,32% for the PUI + 810 nm laser, with no statistically significant differences (p > 0.05). Surface decontamination rates were 39,52%, 51,27%, and 45,20% for the respective groups, also without significant differences (p > 0.05). No significant differences were found regarding smear layer removal (p > 0.05). The 810 nm diode laser with saline achieved disinfection similar to 2.5% sodium hypochlorite with ultrasound. Combining laser and PUI didn't improve disinfection. None of the studied protocol removed the smear layer.