Effect of smear layer on root demineralization adjacent to resin-modified glass lonomer

The cariostatic effect of resin-modified glass ionomer (RMGI) on secondary root caries is well-documented. However, this beneficial effect may be dependent upon the mode of cavity surface treatment. To investigate this relationship, we studied 4 cavity surface treatments prior to the placement of RMGI: no treatment (None), polyacrylic acid (PAA), phosphoric acid (H3PO4), and Scotchbond Multi-Purpose adhesive (SMP) as a control. Specimens were aged for two weeks in synthetic saliva, thermocycled, and subjected to an artificial caries challenge (pH 4.4). Polarized light microscopy (PLM) and microradiography (MRG) showed significantly less demineralization with the H3PO4 cavity surface treatment as revealed by ANOVA and Tukey's multiple comparisons (p less than or equal to 0.05). Dentin fluoride profiles determined by electron probe microanalysis (EPMA) supported PLM and MRG findings. It may be concluded that removal of the smear layer with phosphoric acid provides significantly enhanced resistance to secondary root caries formation adjacent to RMGI restorations.