Evaluation of Antimicrobial Activity of a Novel Pulp Capping Material: an In Vitro Study

Abstract

Introduction: Direct pulp capping is a vital pulp therapy procedure intended to preserve the vitality of exposed dental pulp using biocompatible materials. The success of direct pulp capping depends on the ability of the material to maintain pulpal health, promote dentin bridge formation, and prevent bacterial contamination. Antimicrobial activity of pulp-capping agents is considered an important factor in preventing bacterial invasion and pulpal inflammation

Calcium-silicate–based materials are widely used for vital pulp therapy due to their biocompatibility and bioactivity. Recent advances have focused on modifying these materials with bioactive additives such as chitosan nanoparticles to improve their biological and antibacterial properties. Therefore, evaluation of the antimicrobial efficacy of newly developed pulp-capping materials is essential before clinical application.

Objectives: To evaluate the antimicrobial activity of a novel calcium-silicate–based pulp-capping material modified with chitosan nanoparticles against Streptococcus mutans, Enterococcus faecalis, and Lactobacillus acidophilus using agar disc diffusion and minimum inhibitory concentration (MIC) assays.

Methods: This in vitro study evaluated the antimicrobial activity of an experimental pulp-capping material composed of calcium silicate, calcium phosphate, and a chitosan-reinforced hydrogel binder. The antimicrobial activity was tested using Agar disc diffusion method and Minimum inhibitory concentration (MIC) assay Test microorganisms included Streptococcus mutans (ATCC 25175), Enterococcus faecalis (ATCC 29212) & Lactobacillus acidophilus (MTCC 10307) S. mutans and E. faecalis were cultured on Mueller–Hinton agar, whereas L. acidophilus was cultured on Mueller–Hinton agar supplemented with 2.5% lysed horse blood in accordance with CLSI guidelines. All experiments were performed in triplicate to ensure reproducibility.

Results-The tested pulp-capping material did not produce any measurable zone of inhibition against Streptococcus mutans, Enterococcus faecalis, or Lactobacillus acidophilus at any of the tested concentrations in the agar disc diffusion assay. Minimum inhibitory concentration (MIC) evaluation also showed no significant inhibition of bacterial growth within the tested concentration range. The results were consistent across all three experimental repetitions.

Conclusions: Within the limitations of this in vitro study, the novel calcium-silicate–based pulp-capping material modified with chitosan nanoparticles did not demonstrate antimicrobial activity against Streptococcus mutans, Enterococcus faecalis and Lactobacillus acidophilus.Further modification of the material formulation may be necessary to improve antibacterial properties while maintaining biocompatibility for its use as a direct pulp-capping agent.