上顎切歯位置の変化に対する唇の形の反応

Lip form responses to changes in maxillary incisor position.

• S C Jin
• K Kasai
• T Iwasawa
• E Kanazawa

抄録

顔貌測定用レーザー三次元測定装置の測定精度を評価し、実験的な上切歯の突出による下顔面形態の変化を調べるとともに、口唇形態の変化と口唇厚の関係を検討するための研究を行った。被験者は日本大学松戸歯学部に通う日本人男子歯科学生24名で、オーバーバイト、オーバージェット、正常な咬合を有し、良好な顔貌を有していた。平均年齢は23.2歳、範囲は21.5～25.8歳であった。顔面形態の評価には、コンピュータ化された3Dレーザースキャニングシステムで得られた3次元測定値を用いた。このシステムの測定誤差は、いずれの三次元直線測定においても0.5mm以下であった。記録手順の安定性と再現性を評価した。矯正治療および矯正手術による顔面形態の変化は、この３次元グラフィックシステムによって任意の方向に可視化された。唇の厚さは、唇の形態の変化とは関連していなかった。しかし，唇の左右の角と唇の厚さとの関係が認められた．硬組織と唇の変化の割合については、４ｍｍの突出部の場合の元の位置の値は、４〜８ｍｍの突出部の場合の値と同じではなかった。また、両群の変化の相関性は非常に低かった。唇の厚さの変化はストミオン位置の変化と関連しており、上唇の垂直方向の変化と関連していた。

A study was conducted to assess the measurement accuracy of a laser three-dimensional measurement system for measuring facial profile and to investigate the changes in lower facial morphology caused by experimental protrusion of the upper incisors, and also to examine the relationship between the changes in lip form and lip thickness. The study subjects were 24 Japanese male dental students attending Nihon University School of Dentistry at Matsudo, who had normal overbite, overjet, and normal occlusion, and a good facial profile. The mean age was 23.2 years with a range of 21.5 to 25.8 years. Three-dimensional measurements obtained by a computerized 3D laser scanning system were used to evaluate facial morphology. The measurement error of this system was less than 0.5 mm in any three-dimensional linear measurements. The stability and reproducibility of the recording procedure were evaluated. The changes in facial morphology caused by orthodontic treatment and orthognathic surgery were visualized in any direction by this three-dimensional graphic system. Lip thickness was not associated with changes in lip form. However, a relationship between the right and left corners of lip and lip thickness was noted. With regard to the ratio of changes in hard tissue and lips, the value of the original position for a 4 mm protrusion was not the same as that for a 4-8 mm protrusion. Also, the correlation of the changes in both groups was very low. The changes in lip thickness were associated with changes in stomion position, which in turn were related to the vertical change in the upper lip.