Method: Carious teeth were restored using ART, and a thin partially de-mineralized residual dentine layer (PDRD) was deliberately left to avoid pulp exposure. After scanning the samples by the custom designed MuCAT high contrast XMT system at intervals over an 8 week period, the linear attenuation coefficient (LAC) was measured from the XMT images, indicating the amount of mineral present.
Result: XMT images clearly showed an increase in the LAC in the PDRD over time. This increase was seen as an increase in radio-opacity in the subtracted images. In the adjacent GIC regions, there was a corresponding decrease in the LAC. This change indicates an ionic transport from the cement to the PDRD, demonstrating the potential of these materials to re-mineralize the carious dentine. Fuji IX demonstrated a larger change in LAC than Ketac-Molar, due to the incorporation of strontium instead of calcium in the cement, which is more radiopaque. When the LAC values were converted to mineral concentrations, the observed ion transport was similar in both cements.
Conclusion: This study demonstrates the power of XMT to assess the re-mineralization potential of GICs. It also emphasizes the role of GICs (especially Fuji IX) to potentially re-mineralize the PDRD beneath the restoration.