顔面非対称患者の正貌骨格形態と下顎頭運動路の関連

Abstract

It has been reported that skeletal facial asymmetry is correlated with condyle path asymmetry on protrusive movement. In this article, we investigated the degree and the direction of the condyle path asymmetry on open, protrusive, and lateral movements, and their relationship with skeletal asymmetry in the frontal dimension.The subjects were 35 patients with various facial patterns, (26 females, and 9 males ; mean age, 21.9±4. 8years). Standardized PA cephalograms were used for morphological analysis. The linear and angular measurements were based on the x-y coordinates, the Lo-Lo' plane as the x-axis, and the vertical line through Nc as the y-axis. Reference points, such as Mo, Mo', Go, Go', and Me, were chosen to analyze horizontal and vertical skeletal asymmetries. The measurements were used as skeletal asymmetry variables.Condylar movements were recorded with a computeraided Axiograph (CADIAXR, Gamma). Both horizontal condylar inclination (HCN) on the sagittal plane and the Bennet angle (BEN) on the horizontal plane were measured 5 mm from a reference point (RP), and the shortest distance between RP and the most translated position of the condyle (DIS) on the sagittal plane was measured. The difference between the right and left condyles was calculated and used as a condylar path asymmetry variable. Stepwise linear regression analysis was performed to pick up a valid skeletal asymmetry variable for describing the condylar path asymmetry variable.On open movement, stepwise linear regression analysis selected only deviation of Me as a valid parameter for the HCN difference between both condyles. Deviation of Me was also revealed to be a valid parameter for explaining the differences in HCN, BEN, and DIS on protrusive movement, and the differences in HCN and DIS on lateral movement. Upper dental arch asymmetry and horizontal cant of the occlusal plane were found to be effective parameters for HCN difference on protrusive movement. Upper dental arch asymmetry was also an effective parameter for BEN difference on lateral movement. These results indicated that horizontal and vertical skeletal facial asymmetry had a relationship with condylar path asymmetry in every mandibular movement.