In vitro evaluation of the effect of Er:YAG laser with a fractional PS04 handpiece on microbial biofilm survival.

Abstract

Background: The oral microbiota consists of a diverse range of microorganisms, with Streptococcus spp. and Candida spp. frequently coexisting in oral infections.

Objectives: The aim of the study was to investigate the impact of Er:YAG (erbium-doped yttrium aluminum garnet) laser therapy, utilizing the PS04 fractional beam, on the in vitro growth and biofilm formation of clinical strains of Candida albicans, Candida glabrata and Streptococcus mutans.

Material and methods: Singleand dual-species planktonic cultures and biofilms were exposed to an Er:YAG laser using a fractional PS04 handpiece. The effects of the laser were evaluated immediately after irradiation and 24 h post-irradiation by measuring colony-forming units per milliliter (CFU/mL). Biofilm biomass (singleand dual-species) was quantified using the crystal violet staining method. The study tested 2 sets of laser parameters: group 1 (T1): 1.5 W, 10 Hz, 30 s, 0.4 J/cm2, irradiance: 3.9 W/cm2; and group 2 (T2): 6.15 W, 10 Hz, 30 s, 1.6 J/cm2, irradiance: 16 W/cm2. Non-irradiated samples served as controls. The parameters were selected based on their frequent clinical use for snoring treatment and facial rejuvenation.

Results: Candida albicans exhibited a significantly greater reduction under T2 settings in comparison to T1 (85.3 ±1.2% vs. 43.9 ±4.5%, respectively; p = 0.006) within single-species biofilms. For C. glabrata, a significant reduction was observed under T1 parameters (69.8 ±14.9%). Furthermore, S. mutans demonstrated a significantly higher reduction at T2 settings (97.1 ±0.6%) compared to T1 settings (81.1 ±19.6%), with statistically significant differences noted between S. mutans and both C. albicans and C. glabrata under T1, as well as between S. mutans and C. glabrata under T2. In dual-species biofilms, T2 fluence led to greater reductions in C. glabrata, S. mutans and C. albicans in mixed cultures (p < 0.05).

Conclusions: The Er:YAG laser, when used in conjunction with the PS04 handpiece, demonstrated a substantial reduction in the biofilms of C. albicans and C. glabrata. Higher fluence maintained reductions over a 24-h period, particularly in the case of C. glabrata and S. mutans. This study highlights the antifungal potential of low-fluence laser settings that are commonly used in facial aesthetic procedures and snoring treatment.