Effect of resin-modified glass ionomer cements on secondary caries

To evaluate the in vitro secondary caries inhibitory effect of two resin-modified glass ionomer cements (R-GICs).

Class V cavities were prepared at the cementoenamel junction on facial and lingual surfaces of 32 extracted upper premolars. The facial cavities were restored with a conventional glass ionomer cement (GIC) (Fuji II), while the lingual cavities were restored with either one of the R-GICs (Fuji II LC, Photac Fil, Vitremer), or a resin composite (Z-100). The margins of the restorations were subjected to a 20-day in vitro cariogenic challenge and the degree of demineralization was analyzed by microradiography. The amounts of fluoride released into distilled water from disc specimens of the materials tested were also measured for immersion time up to 161 days.

The R-GICs and GIC's released similar cumulative amounts of fluoride over 161 days. Photac-Fil showed significantly higher amounts of fluoride release over the same period. The depth of the outer lesion and the thickness of the acid-resistant layer showed no significant difference among the R-GICs and GIC's. Moreover, the residual fluoride and calcium in the dentin adjacent to the R-GICs and GIC's were correlated with the thickness of acid-resistant layers in the dentin adjacent to the R-GICs and GIC's by electron probe microanalysis. However, the inhibitory effect of the R-GICs was not directly related to the fluoride concentrations eluted from them.