## 4 Discussion  
The search for new endodontic irrigants is constant. Recent studies have increasingly focused on alternative irrigants and bio-inspired solutions for the disinfection of _E. faecalis_ in root canals [14; 15; 16]. For instance, [PERSON] et al. (2024) investigated the use of 2\({}^{\prime}\)-Fucosyllactose and Lacto-N-Neotetrarose as alternative irrigants. Although their study found no bactericidal effect against _E. faecalis_, it highlights the growing scientific interest in exploring novel, bio-based agents for endodontic disinfection [25]. The aim of this study was to evaluate the anti-planktonic, antibofilm, and synergistic effects of _N. officiale_ and _P. guajava_ hydroethanolic extracts against planktonic and biofilms of the standard (ATCC 29212) and clinical strains of _E. faecalis_, in which it was found that the extracts had effective anti-planktonic and antib Biofilm activities at determined concentrations. Moreover, the combination of both extracts exhibited synergistic and additive effects; thus, the null hypothesis was rejected. In this study, it was not possible to visually read the MIC values of the tested extracts due to the intense coloration of the extracts. Instead, the MBC value of the _N. officiale_ hy  
Figure 2: The microbial viability of the standard and clinical strains of _E. faecalis_ after treatment with the combined extracts. Different letters (a, b, and c) indicate a statistically significant difference among the tested groups. -droethanolic extract, represented by the last well found without turbidity, corresponds to a concentration of 12.5 mg/mL. These results are very similar to the findings of another study that reported the MBC of the _N. officinal_ essential oil at a concentration of 1.25 mg/mL [26]. In addition, in the present study, the MBC value of the _P. guajava_ hydroethanolic extract corresponds to a concentration of 0.52 mg/mL for all the tested strains of _E. faecalis_. In the literature, the aqueous and ethanolic extracts of _P. guajava_ exhibited MIC values ranging from 4 to 24% at different concentrations [27]. Furthermore, the _N. officinal_ hydroethanolic extract at 25 mg/mL effectively reduced the biofilm formation of _E. faecalis_ ATCC, clinical strain 2, and clinical strain 4 by 63.41, 86.24, and 91.25%, respectively, exhibiting a statistically significant difference in the control group (_p_ < 0.0001). Its effectiveness was comparable to that of NaOCl without a statistically significant difference (_p_ > 0.05). In the present study, the MTT assay was used like in different previous studies [12; 13; 28]. Still, to the best of our knowledge, no studies in the literature have evaluated the antibofilm activity of _N. officinal_ against _E. faecalis_. In contrast, the _P. guajava_ hydroethanolic extract was not effective against _E. faecalis_ ATCC; however, it was effective in reducing the biofilm formation of the clinical strains of _E. faecalis_ at different concentrations in percentages ranging from 41.68 to 55.05% against the clinical strain 2, with the concentration of 1.04 mg/mL as effective as NaOCl, and in percentages ranging from 40.46 to 45.08% against the clinical strain 4, with the concentrations of 2.09 and 1.04 mg/mL as effective as NaOCl, all with a statistically significant difference in the control group (_p_ < 0.0001). In the literature, _P. guajava_ was effective against different fungi like _Candida albicans_, _Candida tropicalis_, and _Candida Krusei_ based on the tested microdilution method [21]. This study was pioneered by the idea of testing the combined effect of _N. officinal_ and _P. guajava_ hydroethanolic extracts, making a comparison with other studies in the literature inviable, in which it was found that the extracts at different concentrations were effective in reducing the biofilm formation of the standard and clinical strains 2 and 4 of _E. faecalis_, with a statistically significant difference with the control group (_p_ < 0.0001).