An in vitro model for the study of chemical exchange between glass ionomer restorations and partially demineralized dentin using a minimally invasive restorative technique

Objectives: This study was designed to validate an in vitro model of the Atraumatic Restorative Technique (ART). This model allowed in depth analyses of the migration of apatite forming Sr and F, from a glass-ionomer, Fuji IXGP (GC Corporation, Tokyo, Japan), into partly demineralized dentine. The second objective was to study the effects of the levels of mineral loss on such ionic exchange. Methods: Artificial lesions were created in thirty third molars, which were divided into three groups based on time of exposure to the demineralizing solution (7, 14 and 21 days). These were restored with Fuji IXGP and left for 21 days. The method of analysis was electron probe microanalysis (EPMA) with wavelength dispersive spectrometry (WDS). This combination can yield both qualitative identification of elements as well as quantitative compositional information, with a minimum detection limit of 0.01%. Results: The results indicated that there was no significant difference in the levels of Ca and P from the control and test sides for all three groups of demineralized dentine. The differences in the depth of penetration and the amount of Sr and F between control and test were significant. Conclusions: The validity of the in vitro model was confirmed. There was migration of both strontium and fluorine to the artificially demineralized dentine in a pattern consistent with remineralization and similar to what was observed in a previous in vivo study.