## 4 Discussion  
The microorganisms involved in intracanal infections exhibit high virulence, as they can colonize the root canal system, infiltrate dentin walls, and form bacterial biofilms [29]. These biofilms serve as a crucial adaptive mechanism, enabling microbial survival despite environmental changes induced by endodontic treatment [13,30]. Hence, this study aimed to evaluate the antibacterial and antibiofilm effect of _L. dentata_ essential oil against standard and clinical strains of _E. faecalis_ and _E. facecium_. The selection of both bacteria was based on the literature associating _Enterococcus_ spp. with the persistence of periradicular lesions following endodontic treatment. [PERSON] et al. (2021) [31] reported a higher prevalence of _E. faecalis_ in canals with persistent infections, using both culture growth and PCR techniques for detection. Additionally, [PERSON] et al. (2014) [32] identified _E. facecium_ and _Staphylococcus epidermidis_ as more prevalent in persistent endodontic lesions, employing the DNA hybridization technique. Nevertheless, recently there has been a scarcity of studies linking _E. facecium_ to endodontic infections, likely due to the limited number of investigations utilizing DNA hybridization to differentiate _Enterococcus_ species [33]. The phytochemical profiles of _L. dentata_ essential oils reported in the literature exhibit variability due to differences in major compounds, likely influenced by biological and environmental factors, as well as the time of harvest [34]. However, in another study [35], it was found that _L. dentata_ harvested from different regions of Brazil contained similar compounds, including analogs reported in previous studies, ensuring consistency with the essential oil used in this study. According to the literature, _L. dentata_ essential oil is predominantly composed of oxygenated monoterenes, particularly eucalypt (1,8-cineole) [21,36]. According to [36], it was reported that oxygenated monoterenes constituted 90.38% of _L. dentata_ EO, followed by 7.38% monoterene hydrocarbons. Similarly, according to [21], it was identified that 1,8-cineole (eucalypt) and \(\beta\)-pinene were the most abundant compounds. The _L. dentata_ essential oil tested in this study demonstrated a comparable composition, with 62.02% 1,8-cineole and 17.71% \(\beta\)-pinene, as reported by the manufacturer. It is worth noting that Eucalypt (1,8-cineole) is an oxygenated monoterene with documented antimicrobial activity [37]. In the present study, bacterial inhibition was observed, suggesting that the high concentration of 1,8-cineole (62.02%) contributed to the antimicrobial effect against both clinical and standard strains of _E. faecalis_ and _E. facecium_. It is important to emphasize that the phytochemical variability in essential oils can indeed influence the outcomes of the study, as the composition of essential oils may vary depending on factors such as plant origin, harvesting conditions, and extraction methods. This variability could lead to differences in the antimicrobial efficacy of _L. dentata_ essential oil across different batches. For this reason, the essential oil of _Lavandula dentata_ was used with a concentration of 100%, obtained from the company (Lavanda Brasil, WNF Oleos Essenciais, Sao Paulo, SP, Brazil). In our antibacterial evaluation, _L. dentata_ essential oil at a concentration of 32% (292.8 mg/mL) demonstrated significant efficacy in inhibiting the growth of both _E. faecalis_ and _E. facecium_. However, when lower concentrations of the essential oil were tested, bacterial growth was observed across all the strains, indicating that these concentrations were insufficient to inhibit microorganisms. The minimum inhibitory concentration (MIC) test, which would typically allow for the determination of the lowest concentration of the essential oil capable of preventing bacterial growth, could not be performed. This was attributed to the fact that the process of homogenizing _L.