Effect of open-sandwich vs. adhesive restorative techniques on enamel and dentine demineralization: An in situ study

ObjectivesTo assess in situ the effect of different restorative techniques used with fluoride-releasing materials on enamel and dentine demineralization in the presence of a cariogenic challenge.MethodsThirty human molars were prepared for 60 Class V cavities, with enamel and dentine margins. The teeth were divided into four groups (n = 15): L1 – open sandwich technique with a conventional glass ionomer cement (GIC), L2 – open sandwich technique with a resin-modified GIC, A1 – total-etch bonding with a fluoride-containing adhesive, A2 – total-etch bonding with a nonfluoride-containing adhesive. All the cavities were restored with a nanofilled composite. Fifteen volunteers used appliances containing one specimen from each group. The cariogenic challenge was carried out with a 20% sucrose solution 8×/day for 7 days. The specimens were sectioned for microhardness test and EDS analysis at different depths below the enamel and dentine margins (25, 50 and 100 μm) and distances from the tooth-restoration interfaces (25 and 75 μm). The data were analyzed by ANOVA and Games–Howell test (α = 5%).ResultsBoth GICs produced higher hardness in enamel at all depth-and-distance combinations, but only L1 produced higher hardness in dentine (p < 0.05). L2 and A1 exhibited similar dentine hardness at 25 μm distance for all depths (p > 0.05). L1 demonstrated significantly higher amounts of calcium in dentine than the other groups, but had similar amounts in enamel to L2 and A1.ConclusionsThe open sandwich technique using conventional GIC proved more effective in reducing enamel and dentine demineralization at depths of up to 100 μm under a cariogenic challenge.Clinical significanceConventional GICs should be considered the materials of choice for lining of cavities not having all margins in enamel, particularly using the open sandwich technique.