Antimicrobial photodynamic therapy with erythrosine and blue light on dental biofilm bacteria: study protocol for randomised clinical trial

INTRODUCTION: The objective is to investigate the effect of antimicrobial photodynamic therapy (aPDT) mediated by erythrosine and a blue light-emitting diode (LED) in the reduction of bacteria in dental biofilm. METHODS AND ANALYSIS: This clinical trial will be conducted with 30 patients who have biofilm, but without the presence of periodontal pockets, and who are being treated at the Dental Clinic of Universidade Metropolitana de Santos. A split-mouth model will be used (n=30), with group 1 control (conventional treatment) and group 2 (conventional treatment and aPDT). The bicarbonate jet will be used to remove dental biofilm in both groups. The treatment will be carried out in one session. aPDT will be performed before cleaning/prophylaxis, only in group 2. Participants will rinse with the photosensitiser erythrosine (diluted to 1 mM) for 1 min of pre-irradiation time, so that the drug can stain all the bacterial biofilm. Then, the D-2000 LED (DMC) will be applied, emitting at a wavelength of ʎ=470 nm, radiant power of 1000 mW, irradiance of 0.532 W/cm(2) and radiant exposure of 63.8 J/cm(2). Irradiation will be performed until the biofilm of the cervical region is illuminated for 2 min/point (4 cm(2)). The microbiological examination will be performed from samples of supragingival biofilm collected from the gingival sulcus. Collection will be performed in each experimental site before irradiation, immediately after the irradiation procedure and after the prophylaxis. Colony-forming units will be counted and the data will be submitted for statistical analysis for comparison of pretreatment and post-treatment results and between groups (conventional X aPDT). ETHICS AND DISSEMINATION: This study has been approved by the Ethics Committee of Universidade Metropolitana de Santos under process number 66984123.0.0000.5509. Results will be published in peer-reviewed journals and will be presented at conferences. TRIAL REGISTRATION NUMBER: NCT05805761.