Antimicrobial Efficacy of Triple Antibiotic Paste and Amoxicillin–Clavulanate against Enterococcus faecalis: A Comparative In Vitro Study

Background: Persistent endodontic infections caused by Enterococcus faecalis remain a leading cause of root canal treatment failure due to the organism's resistance and ability to survive in harsh intracanal environments.Triple antibiotic paste (TAP) is widely used for intracanal disinfection but has drawbacks such as tooth discoloration, cytotoxicity, and reduced dentin strength.Amoxicillin-clavulanate paste (ACP) has been proposed as a potential alternative owing to its broad-spectrum activity and favorable handling characteristics.This study aimed to compare the antimicrobial efficacy of TAP and ACP against E. faecalis using an in vitro model. Materials and methods:An in vitro study was conducted on 80 extracted single-rooted human teeth inoculated with E. faecalis (ATCC 29212).Samples were divided into four groups (n = 20 each): Group I: TAP, Group II: ACP, Group III: Calcium hydroxide (positive control), and Group IV: Normal saline (negative control).The antibacterial efficacy was evaluated by counting colony-forming units (CFUs/mL) on days 1, 7, and 10.Data were analyzed using two-way analysis of variance (ANOVA), one-way ANOVA, and Tukey's post hoc test with a significance level of p < 0.05.Results: Both TAP and ACP showed a significant and progressive reduction in E. faecalis counts over time (p < 0.0001), demonstrating comparable antimicrobial efficacy.Calcium hydroxide exhibited moderate antibacterial activity, while normal saline showed the least effect.Conclusion: Amoxicillin-clavulanate paste showed antimicrobial efficacy comparable to TAP against E. faecalis, suggesting it as a promising alternative intracanal medicament.