Antimicrobial photodynamic therapy protocol for dental implant surfaces decontamination in vitro: A comparison between methylene blue and toluidine blue O

Peri-implantitis is one of the most important complications related to dental implants, and there is still no consensus about a protocol for treatment. This study aimed to compare an antimicrobial photodynamic therapy protocol using methylene blue or toluidine blue O, and the efficacy of these two dyes without light activation against human oral biofilm associated with peri-implantitis. Twenty-four dental implants (Classic-CI^®, Systhex Dental Implants) were divided into six groups (n = 4): NC – sterile implants (negative control); PC – contaminated implants (positive control); MB – contaminated implants, decontaminated with methylene blue (0.01%, 1 min); aPDT MB – contaminated implants, decontaminated with antimicrobial photodynamic therapy (MB + red laser); TBO – contaminated implants, decontaminated with toluidine blue O (0.01%, 1 min); aPDT TBO – contaminated implants, decontaminated with antimicrobial photodynamic therapy (TBO + red laser). Microbiologic analysis was performed by counting the colony-forming units (CFUs). Statistical analysis used One-way ANOVA test and Tukey post-test to compare the experimental groups, with a significant level of 5%. Both groups treated with antimicrobial photodynamic therapy were similarly effective against the biofilm, compared to group C (p < 0.001). Dyes alone were similar (p = 0.518) and had no antimicrobial effect. The antimicrobial photodynamic therapy protocol was effective in implant decontamination in vitro regardless of the photosensitizer used, and the dyes without light activation do not seem to be an indicated method for this purpose.