Changed calcium profiles in demineralised dentine following indirect pulp capping

In previous studies (Vu, 2006), class one cavities with artificially generated dentinal caries were restored in Fuji IX and supplied with Simulated Dentinal Tubule Fluid (SDTF) via the pulp chamber. Increased calcium levels on both control and test side in some samples indicated a need for a model modification to gain further information on calcium baselines in dentine. Objective: To determine calcium profiles in demineralized dentine under different experimental conditions. Materials and methods: Demineralized dentine was generated into occlusal cavities in 12 intact extracted third molar teeth which were sectioned 1mm below CEJ to remove the root, then hemi-sectioned mesio-distally. Each half of the tooth was restored in GIC in one experiment and composite resin in the other, and afterward sealed onto a Perspex base. The restored halves were connected to a system supplied with SDTF or De-ionized Distilled Water (DDW) under specific hydrostatic pressure for 21 days, then detached from the system and prepared for Electron Probe Microscope Analysis (EPMA). Mineral profiles in weight percent were measured in dentine. Calcium and strontium profiles were compared between samples. Results: Calcium levels increased significantly in demineralized dentine under composite and GIC restorations supplied with SDTF while there was no increase in calcium levels in those supplied with DDW (significant at 5%). Diffusion of strontium into demineralized dentine under GIC restorations was observed at a low level. Discussion and conclusion: The model enabled a comparison of calcium profiles between two halves of the tooth. Calcium profiles in samples supplied with DDW could be considered as calcium baseline. Increased calcium in samples supplied with SDTF suggested that SDTF has the potential to increase calcium concentration in demineralized dentine in relation to those initially present. This would explain the effectiveness of the indirect pulp capping technique in achieving better remineralization of remnant demineralised dentine.