2018 Volume 61 Issue 6 Pages 361-367
Purpose: In this study, we compared anti-demineralization of dentin by a conventional glass ionomer cement with that of a newly developed glass ionomer cement with a glass containing zinc, fluoride and calcium using transverse microradiography (TMR). We also analyzed the elements incorporated in the dentin using an electron probe micro-analyzer (EPMA).
Method: Eighteen samples of bovine root dentin were divided equally into three groups. The F7 group was covered by a 100 μm-thick Teflon sheet with a 2×3 mm cut-out onto which Fuji Ⅶ conventional glass ionomer cement was then pressed. The C10 group was similarly covered but ZincF-C10 cement was applied. The cements had been prepared according to the manufacturer’s instructions. The Teflon sheet and excess cement were removed after five minutes. The third group, the control, was not treated with cement. The entire surfaces of all 18 samples, except for a 2×3 mm area on each sample, were painted with acid-resistant varnish. In the F7 and C10 samples, the 2×3 mm area was adjacent to the cement. Each group of samples was fixed to the bottom of a separate container and demineralized by leaving for four days at 37℃ covered in acidic solution (1.5 mmol/l CaCl2, 0.9 mmol/l KH2PO4, 50 mmol/l acetic acid, 0.1 ppm F, pH 5.0) which was refreshed every 24 hours. Sections 300 μm in thickness were prepared and examined by TMR. The mineral profiles and integrated mineral loss (IML) of lesions in each group were analyzed by dedicated software. Fluoride concentration of each demineralization solution was also measured. Statistical analysis of IML was performed with one-way ANOVA and Tukey’s test at p<0.05. Elements (Ca, P, F, Zn) incorporated into the demineralized dentin of C10 were detected on the cut surface by EPMA.
Results: Compared to the other two groups, the C10 group showed higher mineral volume% in the surface layer and in the lesions, indicating that IML of C10 was significantly lower than for the other groups (p<0.05). EPMA line profiles of the C10 specimens showed Zn in an extremely thin region at the dentin surface, and F was incorporated at a depth of 40 μm from the surface. Ca and P had similar line profiles to the TMR profile. The concentration of fluoride was higher in demineralization solution of C10 than in that of F7.
Conclusion: Glass ionomer cement containing zinc glass is more effective than conventional glass ionomer cement at reducing demineralization of dentin.
