Antimicrobial efficacy of indocyanine green laser ablation compared to methylene blue photodynamic therapy in root canals contaminated with Escherichia coli

• Grant number: 23/02279-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2023
• End date: June 30, 2024
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Principal Investigator: Rogerio de Castilho Jacinto
• Grantee: Caroline Alponti Sacoman
• Host Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

Antimicrobial photodynamic therapy (aPDT) is used as an adjunct to endodontic treatment to enhance microbial reduction. This in vitro study aims to evaluate the efficiency of laser ablation with indocyanine green compared to aPDT using methylene blue (MB) photosensitizer in reducing E. coli biofilms in root canals. The sample will consist of 80 bovine teeth, divided into four groups, according to the decontamination protocol: MB+RL (n=20) (Methylene Blue + Red Laser); ICG+DL (n=20) 2.5/300/100 (Indocyanine Green + infrared diode laser 2.5 W power, 300 ms interval and 100 ms duration); negative control (n=20) and positive control group (n=20). The collection of root canal content will be performed in two moments, 21 days after bacterial contamination (S1) and immediately after the different treatment protocols (S2). Each canal will be filled with sterile saline solution (1 ml), and three tips of #80 sterile absorbent paper (Dentsply Maillefer, Switzerland) will be inserted into the canal for 1 minute. Then, the paper tips will be transferred to Eppendorf tubes containing 1 ml of sterile Ringer's solution (Sigma-Aldrich, St. Louis, MI, USA). Each sample will be homogenized and diluted 104 before and 101 after the different treatment protocols. The dilutions will be cultivated in BHI agar plates and incubated for 24h at 37ºC. Microbial growth will be determined by counting the number of colony forming units (CFU/ml) of E. coli.