高速度カメラを用いた口唇の発語運動解析  [in Japanese] Measurement of lip movement using high speed cameras  [in Japanese]

本研究の目的は高速度カメラを用いて顔面軟組織の運動解析ができる三次元的評価方法を確立し,前歯部不正咬合をシミュレーションし口唇の運動様相の正常被蓋時との差を検討することである.発語運動計測システムとして3台の高速度カメラで口唇の動きを撮影し,三次元動作解析ソフトで解析した.まず本計測システムの精度検証を行った.被験者に個人正常咬合の成人女性10名を用いた.顔面の不動点を額2点と鼻点で構成される三角形の重心とし,動作計測点すなわち上下口唇点,口角点までの[a],[sa],[ma]の単音発音時の三次元距離計測をした.また上下顎前歯部にアタッチメントを装着し不正咬合モデルとし,正常被蓋時と比較した.1.距離計測は標準誤差が0.20mm以下,撮影空間内のノギス実測値との相関係数が0.99,標準誤差は0.02mm以下であった.自動追尾の精度も追従性に支障がなく,本システムは口唇運動解析を行うのに十分な精度を有していることが確かめられた.2.正常被蓋時,上唇では[ma],口角と下唇では[a]の動きが相対的に大きく,[sa]では階段状の動きをするなど発語によって口唇の運動に特徴がみられた.3.上顎前歯前突モデルでは上唇と下唇,下顎前歯前突モデルでは上唇の動きが正常被蓋時と比べ有意に大きく,不正咬合モデルを用いることで前歯被蓋の変化に伴う口唇の動きに補償運動がみられることが示唆された.以上のことから前歯被蓋は発語動作時の口唇の動きを歪めており,矯正治療でこれらが改善される可能性が示唆された.

We introduced the three-dimensional evaluation system of facial movement with high speed cameras and movement analysis software. We determined the measurement accuracy of it, and analyzed the lip movement of 10 adult females with individual normal occlusions. Marker were placed on subject's forehead and nose as facial reference points, and on the upper, lower lip and corners of the mouth as measurement points. The distance from the center of reference points to each measurement point was recorded during pronouncing [a], [sa], [ma]. Then attachments were set on anterior teeth to simulate two types of malocclusions, i.e. upper and lower incisor protrusion, and the lip movement in malocclusion was compared to that in normal. Results were as follows. 1) This system precision was enough to analyze facial movement. 2) The movement for the upper lip in [ma], for the corners and the lower lip in [a] were significant, and two peaks of movement was found in [sa]. The lip movement was characteristic in each pronunciation. 3) The movements for the upper and lower lip in upper incisor protrusion and for the upper lip in lower incisor protrusion were significantly larger than those for normal occlusion. Compensatory movement of lip was found in malocclusion. These results suggest the anterior teeth malposition influences on the lip movement in pronunciation and orthodontic treatment is considered to be valuable to get normal lip activities.