## 1 Introduction  
_Enterococcus_ spp. has undergone several taxonomic revisions before ultimately being designated by this name [1]; belongs to a group of microorganisms known as lactic acid bacteria (LAB); and is characterized as Gram-positive, facultative anaerobic cocci that occur singly, in pairs, or in chains [2]. One of its most notable characteristics is its remarkable ability to survive and adapt to a wide range of environmental conditions that are typically unfavorable to other bacterial species. This adaptability provides _Enterococcus_ spp. with a significant ecological advantage, allowing it to persist in hostile environments and facilitating its dissemination in various habitats, including the human oral cavity [3; 4; 5]. Among the species within this genus, _Enterococcus faecalis_ and _Enterococcus fiecium_ are of clinical relevance due to their frequent association with endodontic and periodontal infections. These microorganisms have been widely detected in the root canal system of teeth diagnosed with periapical periodontitis, where they are known to contribute to persistent infections and endodontic treatment failure. Additionally, they have been isolated from subgingival biofilms in patients with periodontitis and gingivitis, suggesting a role in the pathogenesis and progression of periodontal disease. Their ability to survive harsh conditions, including high pH levels, low oxygen availability, and antimicrobial challenges, further underscores their clinical significance in dentistry [6; 7]. Over the past two decades, numerous studies have investigated the role of _Enterococcus faecalis_ in persistent endodontic infections. Its ability to form resilient biofilms, penetrate dental tubules, and survive in nutrient-deprived environments has been well-documented [6; 7]. In contrast, _Enterococcusecium_, although less frequently studied in the context of endodontics, is emerging as a significant pathogen due to its increasing antimicrobial resistance and adaptability ([PERSON] et al., 2014 [8]; [PERSON] et al., 2021 [9]). Most of the existing research has focused on _E. faecalis_, with limited attention paid to _E. fecium_, despite its growing clinical relevance. During the root canal treatment of infected teeth, the main goal is to eliminate the microbial load, including _E. faecalis_ and _E. fecium_, by cleaning and shaping the root canal system [10] using mechanical instruments, chemical agents like sodium hypochlorite [11], and intracanal medications [12]. However, biofilm formation by _Enterococcus_ spp. in the root canal system exhibits high resistance to biomechanical preparation and intracanal medication, while also modulating the host's immune response. The persistent presence of biofilm within the root canal contributes to the failure of complete microbial elimination, serving as a key factor in the persistence of periapical lesions [13]. Given the persistent challenge of microbial resistance in endodontics, the search for new and more effective antimicrobial agents remains an ongoing priority. In this context, the use of herbal medicines is gaining increasing attention [14], and in particular the application of essential oils [15; 16]. To overcome the limitations of conventional disinfectants, such as cytotoxicity and incomplete biofilm elimination, several studies have explored plant-derived essential oils for their antimicrobial potential in endodontics. Essential oils from _Melaleuca alterifolia_ (tea tree), _Origanum vulgare_ (oregano), _Thymus vulgaris_ (thyme), and _Cymbopogon citratus_ (lemongrass) have demonstrated varying degrees of success in inhibiting _E. faecalis_ and other endodontic-related microorganisms in both planktonic and biofilm forms [16; 17; 18; 19]. _Lavandula dentata_ L., commonly known as French lavernder or toothed lavernder, is a flowering plant of the Lamiaceae family, native to the Mediterranean basin, Eritrea, Ethiopia, Yemen, and the Arabian Peninsula as documented by the Board of Trustees of the Royal Botanic Gardens, Kew [20]. _L.