Photodynamic antimicrobial chemotherapy using indocyanine green in experimentally induced intraoral ulcers in rats

Photodynamic antimicrobial chemotherapy (PACT) is a promising modality for eradication of microorganisms from the wound. This study aimed to investigate the effectiveness of PACT using indocyanine green (ICG) for reduction of bacterial load of oral ulcers in rats and its impact on the healing process.

In this experimental study, 50 adult male Sprague Dawley rats were recruited. Oral ulcers were surgically made on the left cheek mucosa, and animals were randomly assigned into five groups (n = 10). Wound site in groups 1, 2, and 3 was irrigated with the sterile saline (0.9%), chlorhexidine (CHX; 0.2%), and ICG solutions (1 mg/mL), respectively. Group 4 was exposed to laser irradiation using 810 nm diode laser on continuous-wave mode for 30 seconds (fluence: 55 J/cm² , power: 300 mW, spot size: 4.5 mm). In group 5, PACT was performed using topical application of ICG followed by laser irradiation in the same way as the previous group. Bacterial load of oral ulcers was assessed before and after each treatment modality. Besides, rats were sacrificed on the 5th day post ulceration and histological features of healing were evaluated.

Bacterial load was significantly reduced merely in the PACT-ICG-treated group by one log (P < .0001). Animals in the PACT-ICG-treated group also showed an accelerated healing in comparison with others on the 5th day of an experiment.

Photodynamic antimicrobial chemotherapy using topical application of ICG has a potential to reduce the bacterial load of oral ulcers and accelerate wound repair. Therefore, it can be considered as an alternative to currently available modalities for wound management.