Evaluating thymol vapor for biofilm removal and biocompatibility in curved root canal models

Background/purpose: Conventional irrigants such as chlorhexidine and sodium hypochlorite have strong antimicrobial properties but high cytotoxicity, limiting their use in regenerative endodontics. We hypothesized that thymol vapor could provide effective antibacterial activity with lower cytotoxicity. Materials and methods: The antimicrobial activity of thymol in both liquid and vapor phases was tested against Results: Thymol exhibited minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) values of 0.8-1.0 mg/mL in planktonic cultures. In early-stage biofilms models, 10-100 mg/mL liquid thymol and 5.0 mg/mL thymol vapor significantly reduced bacterial viability. Combining 1.0 mg/mL thymol vapor with mechanical instrumentation enhanced early-stage biofilms removal, particularly against Conclusion: This study is the first to propose thymol vapor for biofilm removal in curved root canal models and to demonstrate its antibacterial activity with lower cytotoxicity than conventional irrigants. Its potential as an adjunct in regenerative endodontics merits further investigation, particularly in relation to immunomodulatory effects.