Progression of dental demineralization with and without modified tunnel restorations in vitro

This study evaluated the caries-inhibitory effects of a glass-ionomer cement restoration. As a model to assess these effects, a Ketac-Fil restoration was placed beneath the mesial or distal enamel layer in 14 extracted human molars by means of access from the occlusal fossa. The teeth were insulated in all but two areas on the approximal surfaces. The prepared teeth were mounted on a hollow cylinder and a localized progressing demineralization of the approximal surfaces was induced by storage of the samples in an acidified gel. Immediately before and 14, 21, 28, 35, and 42 days after initiation of demineralization, standardized radiographs were obtained to assess the progression of demineralization. On each radiograph, the demineralized lesions were assessed by measurement of the coronoapical extension (CA) and the central depth (CD). At 28, 35, and 42 days after initiation of the demineralization, the CD of the lesions of the glass-ionomer cement group was revealed to be statistically significantly smaller than the lesions of the control group (no tunnel restoration) (P < 0.1). A multiple linear regression analysis identified CA and time as factors correlated to CD positively and the glass-ionomer restoration as a factor related to CD negatively (P < 0.001). It seems that modified tunnel restorations utilizing glass-ionomer cement inhibit progression of dental demineralization in vitro.