Antibacterial and Antibiofilm Effect of Lavandula dentata L. Essential Oil as Endodontic Irrigant Against Standard and Clinical Strains of Enterococcus spp.

Enterococcus faecalis and Enterococcus faecium are frequently associated with persistent endodontic infections due to their ability to form biofilms and resist conventional treatments. The aim of this study was to evaluate the antibacterial and antibiofilm effects of Lavandula dentata L. essential oil at 100% against the standard and clinical strains of Enterococcus spp. The minimum bactericidal concentration (MBC) of L. dentata essential oil for each bacterial strain was determined. The antibiofilm effect was evaluated by an MTT assay. Data were statistically analyzed by the ANOVA and Tukey test, with a significance level of 5%. The MBC value was 32% (292.8 mg/mL) against all the tested strains. L. dentata significantly reduced E. faecalis and E. faecium biofilms at 16–64% (146.4–585.6 mg/mL) concentrations, with effects comparable to 2% chlorhexidine (CHX) (p ≥ 0.05). Biofilm reduction was strain-dependent at 30 min but showed broader efficacy after 24 h, particularly against E. faecium clinical strains (p ≤ 0.001). L. dentata demonstrated effective antimicrobial activity against planktonic and biofilm forms of E. faecalis and E. faecium as it reduced biofilm formation at a concentration of 16% and 64% (146.4 and 585.6 mg/mL), with results comparable to 2% CHX after 30 min and 24 h. L. dentata EO may serve as a potential alternative or adjunctive antimicrobial agent in endodontic treatment. However, the study’s limitations included the in vitro design and lack of cytotoxicity assessment.