Clinical, Radiographic and Microbiological Evaluation of Antimicrobial Photodynamic Therapy, LASER Versus Chlorhexidine, for Root Canal Disinfection in Primary Molars

Background: Primary teeth preserve arch length and guide permanent teeth, making pulpectomy a key treatment to maintain space and function. It also enhances esthetics, mastication, speech, and overall health while preventing psychological effects of tooth loss. Aim: To evaluate the antimicrobial efficacy of Photodynamic Therapy (PDT) and 980 nm Diode Laser versus 2% Chlorhexidine (CHX) irrigation for root canal disinfection in infected primary molars against Enterococcus faecalis. Materials and methods: The study included 30 Egyptian children (4-6 years) at the Pedodontics Department, Faculty of Dental Medicine for Girls, Al-Azhar University. Patients were divided into three equal groups (10 in each group): Group A (2% chlorhexidine), Group B (diode laser 980 nm), and Group C (photodynamic therapy with 650 nm laser and methylene blue). Parental consent was obtained before participation. Results: Intergroup comparison showed no significant difference before treatment (P = 0.967) but a significant difference after treatment (P < 0.005), with PDT having the lowest bacterial count, followed by the diode laser, while chlorhexidine had the highest. Intragroup comparison (n = 10) showed a significant bacterial reduction (P < 0.05) in all groups: chlorhexidine (1160.0 ± 811.3), diode laser (1080.0 ± 614.2), and PDT (1100.0 ± 611.0). Conclusion: PDT, diode laser (980 nm), and 2% CHX effectively reduce bacteria in primary tooth root canals, with PDT showing the highest efficacy. The diode laser offers a viable alternative to CHX, and combining these methods may improve treatment outcomes.