Calcium-ion Release From Pulp-Capping Materials Through Various Dentin Thicknesses

Objectives: Pulp capping materials provide significant Ca²⁺-release, which may help induce deposition of reparative dentin. This study measured Ca²⁺ ion diffusion through dentin tubules with varying remaining dentin thickness (RDT).
Methods: Caries-free, extracted human molars were selected and ground to remove the roots at the CEJ. Standardized class 1 occlusal cavities were prepared. Pulp tissue was excised and the outermost pulp-side dentin was reduced to obtain samples with four groups based on their eventual RDT values: 0mm; 0.5mm; 1mm; 1.5mm; and 2mm (±0.2 mm). RDT was measured using calipers.

Samples were immersed in 17% EDTA (3-minutes@RT) to remove the smear layer, rinsed with deionized water, and divided into three sub-groups for pulp capping treatment using: 1)Dycal (Dentsply/Caulk, Milford, DE); 2) TheraCal (Bisco Dental, Schaumburg, IL) or 3) an experimental bioactive glass synthesized in our laboratory.

Treatment material was applied as a thin layer in the occlusal preparation. Coronal obturations were completed with composite (Empress Direct, IvoclarVivadent, NY) and the external surface of the samples were covered by nail varnish, except the pulpal cavity, to hamper ion release from the mineral tissues.

Samples were stored at a constant 37°C temperature in 10 mL of deionized water. To simulate 0mm RDT, standardized discs of TheraCal, Dycal, and Bioactive Glass were placed directly into 10 mL of deionized water. As a negative control, both the occlusal and pulpal cavities were filled with composite and the external surface of the samples were covered by nail varnish. Ca²⁺ion-concentration was measured using a Ca²⁺ ion-selective electrode at 2 hours, 24 hours and 48 hours.
Results: As RDT decreased, concentration of Ca²⁺ ions in solution increased. The concentration of Ca²⁺ in all RDT values less than 1.5mm was significantly greater than the negative control (p>0.001.)
Conclusions: Significant Ca²⁺ concentration ions are leached from TheraCal, Dycal, and Bioactive Glass when the RDT is less than 1.5mm. Bioactive glass material provided the highest Ca²⁺ levels.