Antibacterial activity and retrievability of calcium hydroxide incorporated with different nanoparticles: An in vitro study
Abstract
Background: Calcium hydroxide [Ca(OH)₂] is frequently used as an intracanal medicament because of its antimicrobial activity. However, its complete elimination before obturation can be difficult, particularly when nanoparticles are incorporated into the formulation. Persistent medicament remnants may adversely affect sealer adaptation and the quality of the root canal filling. Aim: To evaluate the antibacterial activity of Ca(OH)₂ incorporated with graphene nanoparticles (GNPs), chitosan nanoparticles (CNPs), or titanium dioxide nanoparticles (TiO₂NPs) against Enterococcus faecalis and compare their retrievability using 17% ethylenediaminetetraacetic acid (EDTA) and 18% pamidronate. Materials and Methods: One hundred and eighty extracted single-rooted human teeth were standardized and prepared. Sixty specimens were assigned to four antibacterial groups (n = 15): Ca(OH)₂, Ca(OH)₂ + GNPs, Ca(OH)₂ + CNPs, and Ca(OH)₂ + TiO₂NPs. The other 120 specimens were distributed among eight retrievability groups (n = 15) according to the medicament and chelating solution used, namely 17% EDTA or 18% pamidronate. Antibacterial efficacy was determined from colony-forming unit (CFU) counts. Residual medicament was examined by scanning electron microscopy (SEM) at the coronal, middle, and apical thirds using a fourgrade ordinal scale. CFU values were compared using one-way analysis of variance (ANOVA) with Tukey’s HSD post hoc test. SEM scores were analyzed using the Kruskal–Wallis and Mann–Whitney U tests. Statistical significance was established at p < 0.05. Results: The results demonstrated a significant difference in antibacterial activity among the four formulations (p< 0.001). Ca(OH)₂ + TiO₂NPs demonstrated the lowest mean CFU count (13.67 ± 9.67), followed by Ca(OH)₂ (20.60 ± 21.11), Ca(OH)₂ + GNPs (42.00 ± 35.31), and Ca(OH)₂ + CNPs (68.13 ± 45.69). No significant differences were observed among the eight medicament–chelating agent groups at the coronal (p = 0.277), middle (p = 0.329), or apical (p = 0.144) thirds. Pamidronate-treated groups demonstrated numerically lower residual medicament scores than corresponding EDTA-treated groups, although differences were not statistically significant. Conclusion: Considering the limitations of the present in vitro study, Ca(OH)₂ + TiO₂NPs demonstrated the greatest antibacterial activity against E. faecalis, whereas Ca(OH)₂ + CNPs showed the highest bacterial counts. Pamidronate demonstrated a favorable but non-significant trend toward greater medicament removal than EDTA. Residual medicament increased toward the apical third, indicating the persistent difficulty of complete medicament removal in this region.