咬合変化に伴う顎関節の変化に関する実験的研究

[An experimental study on change in temporomandibular joint following occlusal changes].

抄録

顎関節症の原因を明らかにするために、その原因のひとつと考えられる咬合障害による顎関節の変化に関する実験的研究を行った。本研究では、Macaca fuscatas成体において、咬合金属スプリントによる強制的な下顎遠位位と臼歯欠損の巨視的、X線学的、病理組織学的影響を観察した。実験的処置の前に、側方斜位経頭蓋投影および経咽頭投影を含む標準化された顎関節X線撮影のための個々の投影角度を決定するために、前方投影および軸方向投影を含むセファロX線写真を撮影した。サルの上下の臼歯を抜歯し、残存歯を準備して鋳造金属スプリントを装着した。通常の食事で維持した。術直後、術後10日目、20日目、40日目、83日目に、関節のX線写真観察と咬合の巨視的臨床観察を個別に行った。術後10日目、20日目、40日目、83日目にサルを個別に死亡させ、各顎関節を摘出し、接触マイクロラジオグラフィー、蛍光顕微鏡写真、病理組織学的観察に備えた。得られた結果は以下の通りである：1)マクロ的には、スプリントを固定し大臼歯を抜歯した直後の全閉時の上下の側方歯間の開口は約2mm、前歯部の過蓋咬合は約2mmであった。術後10日目以降、側方歯間の開口は徐々に減少し、スプリント遠位部より咬合接触に近づいた。40日目にはスプリントの咬合面全域が接触し、下顎は後方に位置した。2) セファロX線写真（前方投影および軸位投影）では、実験期間全体を通して下顎骨の変化は認められなかったが、側方ヘッドプレートおよび標準化顎関節X線写真では、術後20日目以降に下顎骨の後方後方への位置が認められ、83日目には顆頭後面に骨吸収が認められた。3) コンタクトマイクロラジオグラフィーおよび蛍光顕微鏡写真による観察では、外側翼突筋挿入部、後関節突起前面および顆部後面の頚部に骨吸収が認められた。

In order to clarify the cause of temporomandibular arthrosis, an experimental study on change in temporomandibular joint resulting from faulty occlusion which is thought to be one of the causes was performed. In this study, macroscopic, radiologic and histopathologic effects of a forced distal positioning of the mandible by occlusal metal splints and loss of posterior teeth in adult Macaca fuscatas were observed. Cephalometric radiograph including posteroanterior and axial projection were taken to determine the individual projection angle for standardized TMJ radiography including lateral oblique transcranial and transpharyngeal projection prior to the experimental procedures. The upper and lower molars of the monkey were extracted and the remaining teeth were prepared and the cast metal splints were adhered in place. They were maintained on their regular diet. Radiographic observation of the joints and macroscopic clinical observation of the occlusion were made individually, immediately after operation, at the 10th, 20th, 40th and 83rd day postoperatively. The monkeys were killed individually at the 10th, 20th, 40th and 83rd day postoperatively, each temporomandibular joints were removed and prepared for contact microradiographic, fluorescent micrographic and histopathologic observations. The results obtained were as follows: 1) Macroscopically, the opening between the upper and lower lateral teeth in full closure was about 2mm, overbite about 2mm in anterior teeth immediately after the splints were adhered in place and molar extraction. The opening between the lateral teeth decreased slowly after the 10th day postoperatively and they were approximating occlusal contact from the distal area of the splints. The whole area of the occlusal surface of the splints came into contact and the mandible positioned posteriorly by the 40th day. 2) Though the cephalometric radiographs in posteroanterior and axial projection did not show the changes of mandible through the whole experimental period, lateral head plates and standardized TMJ radiographs showed posterosuperior positioning of the mandible after 20th day postoperatively, and osseous absorption in the posterior aspect of the condyle at the 83rd day. 3) Contact microradiographic and fluorescent micrographic observations showed osseous remodeling in the neck of condyle at the site of the insertion of the lateral pterygoid muscle, anterior aspect of the retroarticular process and posterior aspect of the condyle.(ABSTRACT TRUNCATED AT 400 WORDS)