歯内療法で治療した歯の破折抵抗性に及ぼすポストの適合の影響

Effect of post adaptation on fracture resistance of endodontically treated teeth.

抄録

この研究では、歯内療法で治療した歯の破折抵抗性に及ぼすポストの設計の違いとポストとカナルの適合量の違いによる影響を検討した。40本の抜歯したての上顎中切歯を歯内療法した．10歯のグループを4つの実験デザインに従って準備した．鋳造ポストとコア，クラウンをワックスで鋳造し，静的負荷装置でリン酸亜鉛セメントで合着した．歯はアクリルレジンに埋入され，クラウンは万能試験機で歯の長軸に対して130°の角度で破折するまで負荷された．テーパーポストによる残存歯根構造の最大適合は，歯内療法で治療した歯の耐破折性を著しく向上させるが，破折すると歯は修復不可能となる．テーパーポストでは、破折の方向がより歯端側と舌側に偏った。平行面支柱は、破折の頻度が低く、歯質への影響が少なかった。多量のセメントで囲まれた平行面ポストは、破折荷重に有意な影響を与えなかった。

This study determined the effect of different post designs and varying amounts of post-to-canal adaptation on the fracture resistance of endodontically treated teeth. Forty freshly extracted maxillary central incisors were endodontically treated. Groups of 10 teeth were prepared according to four experimental designs. Cast post and cores and crowns were waxed, cast, and luted with zinc phosphate cement on a static loading device. The teeth were embedded in acrylic resin and the crowns were loaded on a universal testing machine at 130 degrees to the long axis of the tooth until failure. Maximum adaptation of the residual root structure with a tapered post significantly increases the fracture resistance of endodontically treated teeth, but upon failure renders the tooth nonrestorable. Tapered posts resulted in fractures that were directed more apically and lingually. Parallel-sided posts had a lower frequency of fracture upon failure, involving less tooth structure. Parallel-sided posts surrounded by large amounts of cement had no significant effect on failure loads.