## 4 Discussion
dentata_ essential oil with Tween 20, followed by mixing it with the Mueller-Hinton medium, resulted in the development of turbidity. This turbidity rendered it impossible to visually assess bacterial inhibition through standard optical methods, thus preventing the reliable determination of the MIC. The present study demonstrated that _L. dentata_ essential oil at concentrations of 16% (146.4 mg/mL) and 64% (585.6 mg/mL) led to a reduction in the bacterial load of monotypic biofilms of the standard and clinical strains of _E. faecalis_ and _E. ficeium_, being as effective as the 2% CHX group after 30 min. According to another study, _L. dentata_ essential oil at concentrations of 1.5-6% can inhibit or prevent the formation of _E. faecalis_ biofilms [25]. To the best of our knowledge, there were no studies in the literature that evaluated the antibacterial or antib biofilm effect of _L. dentata_ essential oil against _E. ficeium_. Nevertheless, _L. dentata_ essential oil was effective in reducing the biofilm formation of _Escherichia coli_, _Candida albicans_, and _Streptococcus pyogenes_[22]. Additionally, in the present study, after 24 h of treatment, _L. dentata_ essential oil at the concentrations of 16% (146.4 mg/mL) and 32% (292.8 mg/mL) was effective in reducing the biofilm formation of the standard and clinical strains of _E. faecalis_ and _E. ficeium_ with a statistically significant difference in the control group. The observed higher biofilm eradication at 30 min compared to 24 h for some _Enterococcus_ strains could be attributed to the immediate antimicrobial action of _L. dentata_ essential oil upon contact. Essential oils contain volatile and highly active compounds that can exert rapid bactericidal effects. However, over extended periods, factors such as compound evaporation, degradation, or interaction with biofilm matrix components may reduce their sustained efficacy. Additionally, biofilm dynamics and bacterial stress responses could influence the long-term effects of the treatment. Future studies with time-kill kinetics and extended exposure durations will help further clarify the temporal efficacy of _L. dentata_ essential oil against biofilms. According to [PERSON] et al. (2020) [37], the antimicrobial action of eucalypt occurs by preventing bacterial adhesion, thereby interfering with the initial biofilm formation. This mechanism justifies the observed bacterial load reduction when exposed to _L. dentata_ essential oil, which is crucial for successful endodontic treatment. As stated by [PERSON] and R\(\o\)cas (2008) [38], an ideal endodontic procedure aims to reduce bacterial load to subcritical levels compatible with the healing of persistent lesions. Further studies are needed to precisely quantify these subcritical levels in relation to wound healing. Finally, this is the first study to evaluate the antimicrobial activity of _Lavandula dentata_ essential oil against both clinical and standard strains of _E. faecalis_ and _E. ficeium_ isolated from persistent root canal infections. Our findings demonstrate that _L. dentata_ EO exhibited antibacterial activity against antibiotic-resistant microorganisms within 30 min and maintained its effect over 24 h. The 16% (146.4 mg/mL) concentration appears to be the most suitable, suggesting its potential use as an adjunctive chemical agent in endodontic treatment. Given the frequent renewal of irrigants during root canal procedures, the volatile components of _L. dentata_ essential oil would have increased interaction with bacterial biofilms. Additionally, its use as a vehicle for intracanal medication could be considered, as it effectively reduced bacterial load within 24 h. However, as a limitation, this is an in vitro study, and further in vivo research is necessary to validate these findings before clinical application can be recommended. In addition, this study used commercially obtained essential oils, and no chemical standardization was performed to verify the components reported by the manufacturer.