歯根破折：治癒の種類と破折部位が歯の生存率に及ぼす影響-492例の解析から

Root fractures: the influence of type of healing and location of fracture on tooth survival rates - an analysis of 492 cases.

抄録

目的:

本研究の目的は、歯根破折後の歯の喪失を分析し、治癒の種類と歯根破折の位置が及ぼす影響を評価することである。さらに、実際に歯が失われた原因を分析した。

AIM: The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed.

材料と方法:

432 名の患者の 492 本の歯根破折のデータを用いて長期生存率を計算した．歯牙喪失の原因は、歯髄壊死（歯内療法の失敗を含む）、新たな外傷、過度の可動性のいずれかの結果であると評価された。統計学は Kaplan-Meier 法と log rank 法を用いた．

MATERIAL AND METHODS: Long-term survival rates were calculated using data from 492 root-fractured teeth in 432 patients. The cause of tooth loss was assessed as being the result of either pulp necrosis (including endodontic failures), new traumas or excessive mobility. The statistics used were Kaplan-Meier and the log rank method.

結果および結論:

歯根破折の位置は，歯の生存率に強い有意な影響を与えた（P = 0.0001）．歯根端部骨折の10年歯生存率は89％［95％信頼区間（CI）、78-99％］、歯根中部骨折は78％（CI、64-92％）、歯頚部-歯根中部骨折は67％（CI、50-85％）、歯頚部骨折は33％（CI、17-49％）であった．破折治癒のタイプはさらに予後を左右する情報であった．硬組織骨折治癒の歯では，骨折の位置に関係なく，歯の喪失は観察されなかった．結合組織を挿入した歯では，骨折の位置が歯の喪失に有意に影響した（P = 0.0001）．結合組織が治癒した歯では，歯根端部，歯根中部，歯頸部-歯根中部骨折の推定8年生存率はいずれも80％以上であったが，歯頸部骨折の推定8年生存率は25％（CI，7-43％）であった．肉芽組織を介在させても治癒しない歯については，骨折の位置が歯の喪失に有意な影響を示した（P = 0.0001）．歯牙喪失の原因は，破折部位に大きく依存することが明らかになった．以上より，歯根破折の長期生存率は，治癒の種類と破折部位に強く影響されることが示唆された．

RESULTS AND CONCLUSIONS: The location of the root fracture had a strong significant effect on tooth survival (P = 0.0001). The 10-year tooth survival of apical root fractures was 89% [95% confidence interval (CI), 78-99%], of mid-root fractures 78% (CI, 64-92%), of cervical-mid-root fractures 67% (CI, 50-85%), and of cervical fractures 33% (CI, 17-49%). The fracture-healing type offered further prognostic information. No tooth loss was observed in teeth with hard tissue fracture healing regardless of the position of the fracture. For teeth with interposition of connective tissue, the location of the fracture had a significant influence on tooth loss (P = 0.0001). For teeth with connective tissue healing, the estimated 8-year survival of apical, mid-root, and cervical-mid-root fractures were all more than 80%, whereas the estimated 8-year survival of cervical fractures was 25% (CI, 7-43%). For teeth with non-healing with interposition of granulation tissue, the location of the fracture showed a significant influence on tooth loss (P = 0.0001). The cause of tooth loss was found to be very dependent upon the location of the fracture. In conclusion, the long-term tooth survival of root fractures was strongly influenced by the type of healing and the location of the fracture.