Innovative Nanosilica-Based Triple Antibiotic Paste for Effective Disruption of Enterococcus faecalis Biofilm: A Confocal Analysis

Abstract

Background: Management of pulp necrosis in immature teeth is challenging due to thin dentinal walls and an
open apex, making effective root canal disinfection essential. Enterococcus faecalis, a persistent endodontic
pathogen, forms resistant biofilms that are difficult to eradicate using conventional intracanal medicaments
such as calcium hydroxide (CH) and triple antibiotic paste (TAP). Incorporation of nano-silica into TAP
has been proposed to enhance antimicrobial efficacy and drug delivery. Aim: To evaluate and compare
the antibacterial efficacy of calcium hydroxide, triple antibiotic paste, and nano-silica–incorporated triple
antibiotic paste against E. faecalis biofilms using confocal laser scanning microscopy (CLSM). Materials
and Methods: Dentin specimens prepared from extracted human teeth were sterilized and inoculated with
E. faecalis to allow 7-day biofilm formation. The specimens were then treated with CH, TAP, or nano-silica
TAP for one week. Bacterial viability was assessed using SYTO 9 and propidium iodide fluorescent staining
and analyzed under CLSM. Statistical analysis was performed using the Kruskal–Wallis test followed by
Dunn’s post hoc test. Results: Nano-silica TAP demonstrated the highest antibacterial efficacy, with a
significant reduction in E. faecalis biofilm viability compared with TAP and CH (p < 0.05). TAP alone
showed moderate antibacterial activity, while calcium hydroxide exhibited the least effectiveness, with
the highest percentage of viable bacterial cells. Conclusion: Nano-silica–incorporated triple antibiotic
paste showed superior antimicrobial activity against E. faecalis biofilms compared to conventional TAP
and calcium hydroxide. These findings indicate that nano-silica TAP is a promising intracanal medicament
for enhanced endodontic disinfection; however, further in-vivo studies are required to validate its clinical
applicability.