Time-dependent effect of nanoparticle-based intracanal medicament on root dentin microhardness and their antibacterial efficacy against Enterococcus faecalis.

INTRODUCTION: Persistent endodontic infections are frequently associated with Enterococcus faecalis, which can penetrate dentinal tubules and resist conventional intracanal medicaments. Calcium hydroxide (CH) is widely used but has limitations in antimicrobial efficacy and may adversely affect dentin mechanical properties. Nanoparticle-based medicaments have been proposed to enhance antimicrobial activity and dentinal penetration. METHODS: A total of 140 extracted human single-rooted premolars were instrumented using rotary files and divided into four groups based on the intracanal medicament used: CH, nano-CH (NCH), nanochitosan (NCS), and nanocurcumin (NCU). Antibacterial activity against E. faecalis biofilm was evaluated using colony-forming unit analysis following serial dilution plating. Dentin microhardness was measured using a Vickers microhardness tester at the coronal, middle, and apical thirds after 7 and 14 days. Data were analyzed using One-way analysis of variance and post hoc tests with significance set at P < 0.05. RESULTS: NCU demonstrated the greatest antibacterial activity with the highest reduction in bacterial counts. NCH and NCS also showed significant antibacterial effects compared with conventional CH (P < 0.05). Conventional CH caused the greatest reduction in dentin microhardness, whereas NCS and NCU preserved dentin hardness more effectively. CONCLUSIONS: Nanoparticle-based intracanal medicaments demonstrated superior antimicrobial activity against E. faecalis while maintaining dentin microhardness compared with conventional CH. NCU showed the most favorable overall performance.