Three-dimensional Observation of the Distribution of the Inferior Alveolar Artery Using Micro-CT

Abstract

The purpose of this study was to clarify the distribution of the inferior alveolar artery (IAA) and its dental branches in the mandibular canal and surrounding tissues in both dentulous and edent ulous mandibles using a Micro-CT system. Twenty-six sides of 18 mandibles from Japanese cadavers were examined . Contrast medium was injected into the maxillary artery of the examined specimens to obtain the Micro-CT and 3-D reconstruction images . Maximum vertical length and horizontal breadth of the mandibular canal were measured to determi ne the position of IAA in the canal. The angle of the dental branches against IAA and the inside diameter of IAA were also examined. The vertical position of IAA in the molar area was higher in the edentulous than that in the dent ulous mandible. There was, however, no significant difference in the horizontal position . The retromolar ramus , i n which the dental branches were distributed at the retromolar region , was usually observed to run toward the buccal just after separating from IAA. The inside diameter of IAA was smaller in the edentulous tha n that in the dentulous mandible. These results suggest that positional change of IAA in the mandibular canal and decrease of inside diameter may be caused by absorption of alveolar bone following tooth loss and subsequently morphological change of the mandibular canal. However, the running direction of the retromolar ramus did not change . 抄録:有 歯顎と無歯顎における下歯槽動脈の走行形態および歯枝の分岐形態を把握することを目的として, Micro-CTを 用いた三次元的観察および解析を行った。試料として顎動脈より造影剤の注入を行った日本人成人 遺体18体26側 を用いた。下顎管を基準 とした下歯槽動脈の垂直的位置,水 平的な位置,血 管内径および下歯槽 動脈を基準 とした歯枝の分岐する角度の計測を行ったところ,以 下の結果を得た。下顎管内部における下歯槽動 〒261-8502 千 葉 県千葉 市美浜 区真 砂1-2-2 30 歯 基 礎 誌44: 29-39, 2002. 脈は,無 歯顎になると垂直的には有歯顎と比較して相対的に上方に位置したが,水 平的には差が認められなかっ た。血管内径は無歯顎になると細くなる傾向が認められた。歯枝は歯牙の喪失により分岐する数の減少がみられ たが,臼 後領域に向かう臼後枝は変化が認められなかった。また,そ の臼後枝は頬側方向に分岐していた。これ らは,歯 牙喪失による歯槽骨の吸収,そ れに伴う内部構造,特 に下顎管の構造の変化が大きく関与していた。