Laser plus sodium hypochlorite improves E. faecalis elimination in apical periodontitis

BackgroundPersistent Enterococcus faecalis infection remains a primary cause of endodontic treatment failure, necessitating the development of more effective disinfection protocols. This retrospective case-control study compared the antimicrobial efficacy of semiconductor laser irradiation combined with sodium hypochlorite irrigation vs. sodium hypochlorite irrigation alone for the elimination of E. faecalis from infected root canals.MethodsA total of 102 patients with chronic apical periodontitis and confirmed E. faecalis infection who underwent root canal treatment between May 2024 and June 2025 were retrospectively enrolled. Treatment outcomes were evaluated at short-term 6-month follow-up using clinical and radiographic criteria. Patients were divided into two groups: the laser group (n = 51), which received 810 nm semiconductor laser irradiation combined with 3% sodium hypochlorite irrigation, and the control group (n = 51), which received 3% sodium hypochlorite irrigation alone. Microbiological samples were collected before treatment (S1), immediately after chemomechanical preparation (S2), and after final disinfection (S3). Bacterial counts were determined using colony-forming unit (CFU) analysis, and E. faecalis was identified through polymerase chain reaction (PCR). While quantitative real-time PCR (qPCR) offers advantages in specificity and sensitivity, CFU analysis was employed in this retrospective study as it represents the clinically accessible standard method during the study period. Treatment outcomes were evaluated at 6-month follow-up using clinical and radiographic criteria.ResultsBoth groups demonstrated significant reductions in bacterial load from S1 to S3 (p < 0.001). However, the laser group exhibited significantly greater bacterial reduction rates compared to the control group (98.7 vs. 89.4%, p < 0.001). The complete elimination rate of E. faecalis at S3 was significantly higher in the laser group (92.2%) compared to the control group (74.5%; p = 0.018). At the short-term 6-month follow-up, the laser group showed superior healing rates (90.2 vs. 76.5%, p = 0.043). Multivariate logistic regression identified laser treatment (OR = 3.42, 95% CI: 1.28–9.15, p = 0.014), initial bacterial load (OR = 0.67, 95% CI: 0.49–0.91, p = 0.011), and tooth type (OR = 2.18, 95% CI: 1.05–4.52, p = 0.036) as significant predictors of E. faecalis elimination.ConclusionSemiconductor laser irradiation combined with sodium hypochlorite irrigation demonstrates significantly superior antimicrobial efficacy against E. faecalis compared to conventional irrigation alone, resulting in improved short-term clinical outcomes in the treatment of infected root canals. However, as E. faecalis represents only one component of the complex endodontic microbiota, future studies employing comprehensive microbiological analysis including qPCR and anaerobic culture are warranted to validate these findings across the polymicrobial infection spectrum. Long-term follow-up studies are warranted to confirm the stability of these results.