下顎第3大臼歯根の加齢変化と抜歯後の精神神経麻痺の可能性との関係

Relationship between age-related changes in mandibular third molar roots and the possibility of mental nerve paresthesia after tooth extraction.

抄録

精神神経麻痺は下顎第三大臼歯抜歯の術後合併症のひとつである。下顎第3大臼歯根の表面形態と抜歯後の精神神経知覚麻痺の可能性との関係を検討した研究はないようである。そこで、歯科用コーンビームCT（CBCT）を用いて年齢別に下顎第3大臼歯の歯根形態を調べ、抜歯後の精神神経麻痺の可能性を評価した。本研究では、下顎第3大臼歯抜歯を受けた患者1216人を対象とした。手術前にCBCTを行った791人の1534歯の歯根形態を調査した。評価因子は、年齢、下顎第三大臼歯根の完全形成または不完全形成、下顎第三大臼歯根の歯根膜萎縮、過セメント症、下顎管の変形であった。下顎第3大臼歯の歯根形成は19歳から30歳の間に完了した。下顎第3大臼歯根の完全形成（P=0.002）と下顎管の変形（P<0.001）が精神神経麻痺の危険因子として同定された。これらの所見から、第3大臼歯の抜歯を完全歯根形成前に行えば、精神神経麻痺のリスクを低減できる可能性が示唆された。

Mental nerve paresthesia is a serious postoperative complication of mandibular third molar extraction. It appears that no study has examined the relationship between the surface morphology of the mandibular third molar roots and the possibility of mental nerve paresthesia following tooth extraction. Therefore, the root morphology of the mandibular third molars was examined according to age using dental cone beam computed tomography (CBCT), and the possibility of mental nerve paresthesia following tooth extraction was evaluated. The study included 1216 patients who had undergone mandibular third molar extractions. The root morphology of 1534 teeth in 791 patients who had CBCT performed before surgery was studied. Factors evaluated were age, complete or incomplete formation of the mandibular third molar roots, periodontal ligament atrophy of the mandibular third molar roots, hypercementosis, and mandibular canal deformation. Mandibular third molar root formation was completed between the ages of 19 and 30 years. Complete formation of the mandibular third molar roots (P = 0.002) and deformation of the mandibular canal (P < 0.001) were identified as risk factors for mental nerve paresthesia. These findings suggest that the risk of mental nerve paresthesia could be reduced if the extraction of third molars is performed prior to complete root formation.