Investigation of the physical, chemical, and biological properties of the cockle shell-derived calcium silicate-based pulp capping material: a pilot study.

Introduction: Hard-setting calcium hydroxide-based materials, e.g., Dycal and Life, have been widely used for direct pulp capping. However, various studies have shown undesirable effects such as high solubility and unpredictable dentine bridge formation. Bioceramic, mainly composed of tricalcium and dicalcium silicates, e.g., mineral trioxide aggregate and Biodentine, have provided more desirable physical and biological properties. This study aims to measure the physical properties, chemical properties, and biological response of human dental pulp cells (HDPCs) on three dental pulp-capping materials, Dycal, Life, and cockle shell-derived tricalcium silicate pulp capping material (C-Cap).

Methods: C-Cap was prepared from cockle shells and rice husk ash. Its chemical composition was identified using X-ray diffractometry. The setting time, flow, solubility, and radiopacity tests were performed following the International Organization for Standardization 6876:2012. pH and calcium ion release were measured. The materials were subjected to an extraction medium at various concentrations and subsequently measured for cytotoxicity and migration on HDPCs, from three healthy, mature permanent teeth from different donors. Osteogenic differentiation was assessed by examining alkaline phosphatase enzyme activity and alizarin red staining assay. The data were tested for a normal distribution. The differences among groups were statistically analyzed using ANOVA and Tukey's multiple comparison test (p < 0.05).

Results: The setting time of each material was approximately 1-2 min. C-Cap showed the lowest solubility (10.27% ± 1.02%) compared to Dycal (12.67% ± 0.94%) and Life (12.74% ± 1.33%), with a significant difference (p < 0.05). All materials exhibited radiopacity ranging from 2.4 to 2.9 mm of aluminum. C-Cap had the highest flow, alkalinity, and calcium ion release. C-Cap was significantly less cytotoxic than Dycal and Life (p < 0.05). The migration of HDPCs cultured in C-Cap extraction medium (27.74% ± 0.12%) was comparable to that in serum-free medium (27.09% ± 0.08%) with a significant difference (p < 0.05). The mineralization by HDPCs maintained in C-Cap extraction medium was significantly higher than those in Dycal and Life extraction mediums with a significant difference (p < 0.05).

Conclusions: C-Cap, a tricalcium silicate-based pulp capping material has potential for further development. C-Cap exhibited comparable physical properties and superior biological properties when compared to Dycal and Life.