Synergistic Antimicrobial Effect of Photodynamic Inactivation and SWEEPS in Combined Treatment against Enterococcus faecalis in a Root Canal Biofilm Model: An In Vitro Study

Background: Persistent bacterial infections caused by biofilm-associated Enterococcus faecalis are a global public health concern. This study aims to compare the biofilm removal effects of methylene blue (MB) or hydrogen peroxide (HP) mediated photodynamic inactivation (PDI) with a shock wave enhanced emission photoacoustic streaming (SWEEPS) method laser irradiation enhanced bactericidal activity. Methods: A total of fifty extracted single-rooted human teeth were used. Each canal was then inoculated with a bacterial suspension of E. faecalis and left for ten days to induce biofilm formation. The antibacterial effects within treated root canals using MB or HP + diode laser or SWEEPS alone or in combination were assessed and compared with 5.25% sodium hypochlorite (NaOCl) as the positive control group. Data were analyzed using one-way ANOVA and Tukey's post hoc test. Results: The MB + diode laser + SWEEPS and HP + diode laser + SWEEPS groups displayed significantly lower amounts of bacteria than either the MB + diode laser or SWEEPS and HP + diode laser or SWEEPS groups (p < 0.001). There was no statistically significant difference detected between the diode laser and SWEEPS groups (p = 0.982). Conclusions: SWEEPS can enhance the photosensitizer distribution in the root canal, leading to effective biofilm removal. This technique could thus help promote the future development of endodontic treatments.