顎関節症における下顎側方運動に関する臨床的研究 : 特にMandibular Kinesiographによる水平面記録の解析について

Abstract

Lateral movement of the mandible recorded in patients with temporoman- dibular joint (TMJ) dysfunction and in healthy subjects on the horizontal plane was analyzed by measuring LMA. In accordance with the criteria of the Japan TMJ association standard (1987), 354 patients with TMJ dysfunction were classified into type Ⅰ (50 patients), type Ⅱ (20 patients) and type Ⅲ (284 patients). The patients consisted of 95 males and 259 females, with an average age of 30.4 years (range : 12 to 75 years). Angle from the midine on the horizonal plane during excursion of the mandible to the lateral (Lateral Movement Angle : LMA) was measured in recordings by mandibular kinesiograph (MKG). The patients were also divided into 3 groups according to the occlusal interrelationship of the upper and lower jaw dental arch which guides the mandibular lateral movement as follows ; Mesial (M) type (lateral protrusive), Distal (D) type (lateral retrusive), and Cuspidal (C) type. LMA in the healthy subjects was 60.4° ; in all type Ⅰ, type Ⅱ and type Ⅲ patients LMA on the affected side was larger than that on the healthy side ; 79.8° (type Ⅰ, n=59) ; 75.5° (type Ⅱ, n=21) and 78.1° (type Ⅲ, n=332) on the affected sides, and 66.7° (type Ⅰ, n= 41) ; 63.7° (type Ⅱ, n=19) and 68.8° (type Ⅲ, n=236) on the healthy sides. In the patients with unilateral TMJ dysfunction, LMA difference between affected and healthy sides was 12.5° (type Ⅰ, n=21) : 10.5° (type Ⅱ, n=19) and 10.8° (type Ⅲ, n=238). LMA increase on the affected side may be due to more posterior or less anterior shift of the working-side condyle in the TMJ dysfunction patients. These results indicate that anterior movement of the affected side is restricted and LMA can be a useful marker of TMJ dysfunction. It is concluded that Lateral Movement Angle (LMA) on the horizontal plane in lateral mandibular excursion, as measured by mandibular kinesiograph, may be a useful diagnostic modality.