Preliminary in-vitro antibacterial evaluation of a novel formula of calcium phosphate nanoparticle–chlorhexidine intracanal medicament using confocal laser scanning microscopy

Document Type

Article

Publication Date

5-7-2026

Abstract

Background Bacterial infection in root canals often persist despite thorough chemomechanical preparation. Conventional irrigants and medicaments reduce biofilms but have been accused of weakening dentin. Amorphous calcium phosphate nanoparticles showed promising results in enhancing dentin hardness, but the formula’s anticmicrobial effect is yet to be evaluated in endodontic contexts. The aim of this study was to evaluate the feasibility of using 20% amorphous calcium phosphate nanoparticles loaded in chlorhexidine as an antibacterial intracanal medicament in endodontics. Methods Forty four root dentin discs were prepared from human extracted teeth, sterilized and inoculated with E. faecalis to establish a 3-week-old standard monospecies bacterial biofilm model. After confirming biofilm establishment, forty specimens were randomly divided into four groups (n = 10) according to the medicament used: 20% amorphous calcium phosphate nanoparticles loaded in 2% chlorhexidine (NACP + CHX), 2% chlorhexidine (CHX), calcium hydroxide (Ca(OH)2), and a positive control group. After incubation, the specimens were stained and evaluated under the confocal laser scanning microscope (CLSM). Images were analyzed with Zen imaging software to quantify the percentage of live/dead bacterial cells. For multiple group comparisons, a one-way ANOVA was employed, and for pairwise comparisons, the Tukey post hoc test was used. Statistical significance was determined by a p-value < 0.05. Results All test groups showed a statistically significant bacterial reduction, ranging from 36.81% to 59.19% (p ≤ 0.001). CLSM analysis showed that NACP + CHX and CHX had the highest antibacterial effect without a significant difference between them (p ≈ 0.9). Ca(OH)2 demonstrated the least antibacterial effect amongst the test groups (p ≈ 0.01 × 10-6).

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