Effect of Aging on Mineral Content of Resin-Dentin Interface Treated with Total Etch Adhesives

Abstract

Background/Aim: Slow release of fluoride from adhesives increases the concentration of fluorapatite in the hybrid layer and the underlying dentin and subsequently stabilizes the adhesive joint interface. The present study aimed to evaluate the effect of aging on the mineral content of the bonded resin/dentin interface and to compare between two similar commercial adhesive systems. Materials and Methods:This in vitro study was carried out on 20 caries-free upper and lower human molar teeth. All the procedures of acid etching, application of adhesives and resin composite buildup were restricted to dentin. Each tooth was prepared to receive Adper Single Bond 2 adhesive system on one half (Group I) and Prime & Bond NT on the other half (Group II). Sticks from the same tooth half of each adhesive system were mixed and then randomly divided into 3 subgroups according to storage time regimen: immediate, 3 months and 9 months in distilled water. The mineral content at resin-dentin interfaces was analyzed using an environmental scanning electron microscope and energy dispersive analytical x-ray that was expressed as an atom percentage of the total area evaluated. Oneway ANOVA followed by Tukey's pair-wise comparison test were used to determine the significant effect of aging on the mineral content of resin-dentin interface. Comparison between the two adhesives at different time intervals was done using independent student t test, with p value less than 0.05 considered statistically significant.Results: There was significant difference among different follow up intervals regarding the mineral content of group I (p=0.040), while group II showed non-significant difference at same intervals (p=0.093). When the results of the two adhesives were compared to each other, there was no statistically significant difference between them in all of the storage periods except at 9 months (p=0.050). Conclusions:Both adhesives had an influence on the adhesive dentin interface's durability and resistance to degradation. Prime & Bond NT provided higher mineral content than Adper Single Bond 2 at all storage intervals tested.