Use of Er:YAG Laser for Disinfection of Infected Carious Dentin: Microbiological Evaluation and Scanning Electron Microscopy Analysis

Abstract

Objective:

To evaluate the antimicrobial efficacy of Er:YAG laser for disinfection of softened carious dentin using subablative parameters.

Background:

Current literature lacks robust scientific evidence supporting the use of Er:YAG laser for disinfection of the entire carious dentin without mechanical removal.

Methods:

Ninety permanent third molars were used; 75 were allocated to microbiological evaluation and 15 to scanning electron microscopy. Artificial dentin carious lesions were produced using a microcosm biofilm model, and specimens were randomly assigned to five groups according to the cavity disinfection protocol (n = 15): Group C (positive control)—carious lesions with no disinfection procedure; Group antimicrobial photodynamic therapy (aPDT, negative control)—application of 0.005% methylene blue followed by low-level laser irradiation delivering 9 J of energy; Group Er:YAG, parameter A—irradiation with Er:YAG laser at 50 mJ of energy; Group Er:YAG, parameter B—irradiation at 40 mJ; and Group Er:YAG, parameter C—irradiation at 20 mJ. A repetition rate of 15 Hz was used for all Er:YAG-irradiated groups. Microbiological outcomes (CFU/mL) were analyzed using the nonparametric Kruskal–Wallis test followed by Dunn’s post hoc test, with a significance level set at 5%.

Results:

A significant microbial reduction in dentin carious lesions was observed after irradiation with Er:YAG laser at 50 mJ (parameter A) and aPDT (p < 0.0001). In contrast, irradiation at 40 mJ (parameter B) and 20 mJ (parameter C) did not result in a significant reduction of the cariogenic microbiota (p > 0.05). No significant difference was detected between the microbial reduction achieved with Er:YAG laser at 50 mJ (parameter A) and aPDT (p > 0.05).

Conclusions:

Er:YAG laser irradiation at 50 mJ demonstrated antimicrobial efficacy comparable with aPDT for disinfection of softened carious dentin, with a shorter operative time, supporting its potential use as an alternative treatment in minimally invasive dentistry.