The purpose of this study is to investigate the morphological differences of human dentin after two types of acidic conditioning: etching reagent and self-etching primer using an AFM. The 6 upper first premolars were used in this study. The specimens were divided into three groups: group 1, No-pretreatment; group 2, Etching treatment with 10% citric acid-3% ferric chloride solution in Super-bond C&B system; group 3, an etching treatment with a self-etching primer, ED primer II, in Panavia Fluoro cement. These specimens were divided into the crown and root dentin and were observed
in situ using an AFM. In the no-pretreatment specimen, the diameters of dentinal tubules in both the surface and middle layers of the crown dentin were narrower than in the deep layer of crown dentin. The diameters of dentinal tubules in the root dentin were narrower than that of crown dentin. Furthermore, the peritubular dentin was observed more clearly in the root dentin as compared with the crown dentin. After etching with a 10-3 solution of Super-bond C&B, the peritubular dentin was removed in both the crown and root dentin. The diameters of dentinal tubules were wider than that of no-pretreatment dentin. After ED primer II treatment, the peritubular dentin was removed in the crown dentin, but remained in the root dentin. It was concluded that differences in the dentin region after two types of acidic conditioning were influenced the arrangement of collagen fibers, the amount of collagen, and different sets of matrix proteins in the dentin.
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