Antibacterial efficacy of semiconductor laser-activated 2.5% sodium hypochlorite compared with conventional sodium hypochlorite irrigation in root canal disinfection: a systematic review and meta-analysis

Background The success of root canal treatment depends on the thorough removal of microorganisms from the root canal system. Sodium hypochlorite (NaOCl) is currently the most commonly used root canal irrigation, but its cleaning efficacy is limited. Semiconductor lasers are easy to use and have good tissue penetration; they can enhance the antibacterial effect of NaOCl through thermal effects, the cavitation effect, and chemical activation. Objectives This meta-analysis aimed to compare the bacterial removal efficacy of root canal disinfection using 2.5% NaOCl irrigation assisted by a semiconductor laser versus 2.5% NaOCl irrigation alone. Methods We searched PubMed, Embase, The Cochrane Library, Web of Science, Wanfang Data, VIP and CNKI, to collect randomized controlled trials (RCTs) or in vitro studies comparing the use of semiconductor lasers combined with 2.5% NaOCl versus 2.5% NaOCl alone for root canal disinfection. All databases were searched through January 2026, and a meta-analysis of studies meeting the inclusion criteria was conducted using RevMan 5.4 software. Three researchers independently screened, extracted data from, and assessed the literature according to the inclusion criteria, and the results were pooled for meta-analysis. Subgroup analyses were performed according to study type ( in vivo vs. in vitro ), laser wavelength, and laser power to explore potential sources of heterogeneity. This study was registered in the PROSPERO International Prospective Register of Systematic Reviews (registration number: CRD420261419571). The Cochrane ROB 2 tool was used to assess the risk of bias of included studies and the QUIN tool was used to assess the risk of bias of included in vitro studies. Results A total of 951 articles were identified, and 5 studies (144 samples) were ultimately included. Subgroup analyses stratified by study type showed that bacterial reduction was significant in both in vivo RCTs (SMD = 0.72, 95% CI: 0.19–1.24) and in vitro studies (SMD = 1.32, 95% CI: 0.40–2.24), while bacterial clearance rate reached significance only in the in vivo RCTs (SMD = 2.97, 95% CI: 0.29–5.66) but not in in vitro studies (SMD = 0.32, 95% CI: −0.11–0.75). Only one study (Ahmed 2022) reported visual analog scale (VAS) scores, showing a statistically significant difference between the laser group and the control group ( p = 0.007); however, this finding derives from a single study and should be interpreted with caution; subgroup analysis indicated that the bacterial clearance effect in the 1.5 W laser power group was significantly superior to that in the 0.8–1 W group ( p = 0.002); There were no statistically significant differences between subgroups based on study type ( in vivo / in vitro ) or laser wavelength (445 nm, 810 nm, 960 ± 20 nm). But these findings are based on a limited number of studies (four included studies contributing five datasets) with moderate to high heterogeneity ( I 2 = 63%–85%). Conclusion This study suggests that semiconductor laser-assisted irrigation with 2.5% NaOCl may offer improved bacterial clearance during root canal disinfection, with potential benefits in reducing postoperative pain based on a single study. In subgroup analyses, higher power settings (1.5 W) appeared to be associated with greater effects, but this finding is derived from only two in vitro datasets and should be considered exploratory. However, given the limited and heterogeneous evidence, this technique should currently be regarded as a promising adjunct rather than an established standard protocol. The current evidence is primarily based on in vitro studies and is limited by high heterogeneity and small sample sizes. Therefore, well-designed, large-scale RCTs are needed to validate these findings and establish standardized clinical protocols for laser-assisted irrigation. Systematic Review Registration https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=420261419571 , identifier CRD420261419571.