Direct Bonding Method に関する研究 : 各種酸性処理液によるヒトのエナメル質表面の脱灰効果について

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The efficiency of direct bonding technique in orthodontics depends strongly upon adequacy of pretreatment of the enamel surface. For the purpose of defining the optimal conditions for such treatment, various acids including phosphoric acid and eight different organic acids (pyruvic, maleic, malonic, tartaric, citric, acetic, lactic and formic acid) were examined for their actions on the enamel surface of human tooth. Their effects were monitored by scanning electron microscopic observation of the treated enamel surface as functions of acid concentration as well as treatment time. Phosphoric acid was shown to etch mainly interprismatic matrix, thus leaving horseshoe-shaped depressions of the surface. Enough surface roughness to give adequate bond strength, as judged by scanning electron microscopy, was produced by treating with this acid for 1 or 1.5 min at 5 M or 3 M concentration, respectively. Under these conditions, the extent of enamel dissolution was 10μm. In sharp contrast to phosphoric acid, the organic acids tested preferentially dissolved prismatic cores to leave minor holes on the surface. The conditions of treatment with these acids to give enough surface roughness were : pyruvic acid (2M), 1.5 min ; maleic acid (1M), 1.5 min ; malonic acid (1M), 2.5 min ; tartaric acid (1M), 3 min ; citric acid (1M), 3 min. The extent of enamel dissolution was 2∿3μm under these conditions, irrespective of the kind of acid used. Acetic, lactic and formic acid on the other hand, were found to be far less effective in gaining appropriate surface architecture. Measurement of tensile strength has revealed that the surfaces prepared under conditions described above, when tested with thermosetting acrylic resin, actually provide sufficient grip for usual clinical purposes (4∿6kg/3×3mm^2 or higher). Form these results, it is concluded that such organic acids as pyruvic, maleic, malonic, tartaric and citric acid are superior to phosphoric acid as etching agent in the sense that they require less dissolution of the enamel in obtaining adequate surface roughness for bonding, and the author suggests the following etching scheme to be of clinical choice, considering shortness of the treatment time as well ; 2M pyruvic acid or 1M maleic acid for 1.5 min.
九州歯科学会の論文
1976-01-31

Direct Bonding Method に関する研究 : 各種酸性処理液によるヒトのエナメル質表面の脱灰効果について

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