The effect of storage and the type of adhesive resin on microleakage of enamel margins in class V composite restorations in bovin tooth

Abstract

For success of bonded restorations, the durability of bond between the adhesive resins and tooth substrate is important. Aim: The aim of this study was to compare the microleakage of enamel margins in class V composite cavities restored with two types of adhesive resins (enamel and dentin adhesive resins) in bovine teeth at 24 hours, 6 month and 12 month intervals In-Vitro. Materials & methods: 120 sound extracted permanent bovine incisors were used; the teeth were randomly devided into two groups according to the type of adhesive resin (enamel or dentin adhesive resin) which was used in each group. Then each group was randomly devided into three subgroups, each subgroup contains 20 teeth.(Subgroup 1,evaluation of microleakage 24 hours subsequent to restoration , Subgroup 2,evaluation of microleakage 6 months subsequent to restoration , Subgroup 3,evaluation of microleakage12 months subsequent to restoration ) . At the buccal surfaces of teeth, class V cavities were prepared. At the first group, Subgroup1, the enamel bond (Margin Bond) was applied to the walls of cavity according to the manufacturer's instructions. For restoration of the cavities ValuxTM Plus) 3M, ESPE St. Paul, MN, USA) composite resin was used incrementally. Subsequent to finishing and pulishing, the speciemens were thermocycled .Then they were immerged in 2% basic fushin for 24 hours.Then the teeth were sectioned and enamel microleakage was evaluated by stereomicroscope. In the second and third subgroups, all the stages were similar to the first subgroup.The only difference was that microleakage evaluation was at 6 mounths and 12 months respectively Subsequent to restoration. At this period of time, the teeth were stored at distilled water in the incubator at 37 C. at the second group all of the stages were similar to the first group.The only difference was that the dentin adhesive resin "Adper Single Bond" was applied to the walls of the cavity according to the manufacturer's instructions . Data were analysed by descriptive statistic methods and evaluated by SPSS.15/win software. For comparision of microleakage of three subgroups in each group of bovine teeth, the nonparametric Kruskal-wallis test was used and for two by two comparisions, nonparametric Mann-Whitney U test was used for comparision of the microleakage of the enamel and dentin adhesive resins at each interval. Result: The results of this study showed that the restored teeth in both Adper Single Bond and Margin Bond groups, revealed increased microleakage in enamel margins by the passage of the time. In this study , the difference of mean ranks of microleakage in Adper Single Bond and Margin Bond groups, at 24 hours and 6 months was not statistically significant , but the mean ranks of microleakage at 12 months in Adper Single Bond group was less than Margin Bond group,which was statistically significant (p=0.034). Conclusion: In the present study, Adper Single Bond dentin adhesive resin showed a better durability of bonding to enamel compared to Margin Bond enamel adhesive resin at the enamel margins after 12 months of water storage.