Physicochemical and Antibacterial Evaluation of Novel Nano α-TCP–AgNPs Biocomposites for Direct Pulp Capping Applications

Selviana Wulansari^1,2Hendra Dian Adhita Dharsono¹Nasrul Wathoni³Rosalina Tjandrawinata²Arief Cahyanto^4*Moehamad Orliando Roeslan²

• ¹Universitas Padjadjaran Fakultas Kedokteran Gigi, Sumedang Regency, Indonesia
• ²Universitas Trisakti Fakultas Kedokteran Gigi, West Jakarta, Indonesia
• ³Universitas Padjadjaran Fakultas Farmasi, Sumedang Regency, Indonesia
• ⁴Ajman University of Science and Technology College of Dentistry, Ajman, United Arab Emirates

Background: Nano α-tricalcium phosphate (nano α-TCP) and silver nanoparticles (AgNPs) both possess bioactive qualities needed for pulp capping materials. AgNPs effectively combat microbial infections without sacrificing cell viability, while nano α-TCP can release calcium and phosphate ions, which are necessary for dentin regeneration. To assess the connection between the composite's structure and function, a thorough characterization utilizing FTIR, XRD, SEM, ion release analysis, and pH is necessary. Purpose: This study aims to develop and evaluate a novel biocomposite composed of nano α-TCP and AgNPs for application in direct pulp capping. The investigation will examine the material's chemistry and physical properties, as well as its antibacterial activity against Streptococcus mutans and Lactobacillus acidophilus. Methods: We prepared combinations of nano α-TCP and AgNPs with varying AgNPs concentrations. Subsequently, we analyzed them using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). The investigation focused on pH stability and the release of ions (Ca²⁺ and PO₄³⁺) at 1, 3, 72, and 504 hours. Antibacterial assays performed against Streptococcus mutans and Lactobacillus acidophilus. Results: FTIR and XRD showed that the functional groups and crystallinity in the nano α-TCP matrix remained unchanged following AgNPs incorporation. SEM showed that the particles were evenly spread out with very little agglomeration. The 1% AgNPs concentration showed the best results, with a steady release of ions, a stable alkaline pH that helped with mineralisation, good mechanical strength (according to ISO 9917-1), and strong antibacterial activity. The 1% AgNPs concentration likewise had the most potent antibacterial effect. Conclusion: The nano α-TCP/AgNPs composites, particularly the 1% AgNPs formulation, exhibited sustained calcium and phosphate ion release, stable alkaline pH, adequate compressive strength, and strong in vitro antibacterial activity against Streptococcus mutans and Lactobacillus acidophilus. These physicochemical and antibacterial properties suggest that this biocomposite is a promising candidate for future direct pulp-capping applications; however, its cellular responses and dentin regenerative potential must be confirmed in dedicated in vitro and in vivo studies.