Biomaterials for pulp-capping: calcium-ions pulpflux through dentin in indirect pulp-capping.

Indirect pulp-cap is a procedure following caries removal in which a material is placed on remaining (infected/carious) dentin thickness (RDT). Ca(OH)2-&-CaO-based materials and calcium-silicate MTA (Mineral Trioxide Aggregate) cements are conventionally used for indirect pulp-capping. Ca ions induce the proliferation/differentiation of human dental pulp cells into odontoblasts, the formation of a tertiary/reparative dentin bridge, the mineralization of dentin. OH ions (alkaline pH) create an antibacterial/bacteriostatic environment, cause an inflammatory reaction with the formation of reparative dentin and promote the formation of hydroxyapatite. Objective: To verify the ability of four commercial Ca-containing materials for pulp-capping to generate a Ca ions outflux through dentin in indirect pulp-capping in vitro. Method: Pulpdent Paste Kit (Pulpdent Corp.-USA; lot.n.110411), Dycal (Dentsply-USA; lot.n.110630), Tech Biosealer capping (Isasan-Italy; lot.n.E10046) and ProRoot MTA (Dentsply-USA; lot.n.09001920) were tested. Standardized cavities were prepared (by a high-speed inverted-cone flat-end diamond bur, diam. 0.2mm) in erupted sound human molars. Pulp was removed. EDTA17% was used to remove the smear layer. The outer-surface of samples was covered by nail varnish to hamper Ca-releasing from the dental tissues. Indirect pulp-capping was performed on RDT (1±0.2mm thick) by layering one test material, a glass ionomer cement, a composite, and nail varnish. Samples were maintained deionized water (10ml, 37°C). After 3,24-hours and 3,7,14-days the leached Ca-&-OH ions were measured using ion-selective electrodes. Result: Ca-releasing was Tech Biosealer capping > ProRoot MTA > Pulpdent > Dycal. Only Tech Biosealer capping released significant amount of calcium. Alkaline pH of soaking water was observed after 24-hours. Conclusion: Only Tech Biosealer capping was able to create a calcium ions outflux through dentin. In clinical situation, the wet surgical site owing to the presence of biological fluids (blood, exudates, dentinal fluid) may supply calcium ions, with beneficial effects on pulp cells, tissue regeneration (reparative dentin formation) and clinical healing.