成人安格氏一級咬合併有前牙開咬治療之考量

Consideration of Therapy in Angle Class I Malocclusion with Anterior Open Bite

前牙開咬為常見且極具挑戰性的咬合型態，成年患者呈現 Class I molar relationship，合併有 high mandibular plane angle, maxillary canting, anterior open bite, discrepancy of anterior Bolton ratio, bilateral posterior crossbite 等多面向問題，宜妥善考量治療的選擇，不一定非要正顎手術的配合才能改善咬合及外觀。患者為22歲女性，主訴前牙開咬，有吐舌癖（tongue thrust）。使用非手術的矯正治療原則為改變咬合平面，強調垂直向的控制，且在改善前牙開咬的同時，引導患者下顎逆時針旋轉。初期利用TPA、 tongue crib 舌側裝置來加強垂直控制、改正吐舌癖並同時利用齒性代償來更正兩側錯咬的問題，在中期開始Chewies exercise 來持續垂直控制，若積極配合可達到理想的肌肉訓練效果，後期Chewies exercise再搭配 Class III 橡皮筋來達到下顎齒列移動而獲致類似Multiple Edgewise Arch Wire （ MEAW therapy ）的效果。

Anterior open bite is a common and challengeable malocclusion. To manage Angle Class I molar relationship in adult cases with several problems, such as high mandibular plane angle, maxillary canting, anterior open bite, discrepancy of anterior Bolton ratio and bilateral posterior crossbite, we should choose therapeutic method carefully. It is not necessary to improve occlusion and profile with orthognathic surgery. A case of an adult woman with tongue thrust had the chief complaint of anterior open bite. The principle of orthodontic treatment without orthognathic surgery is the occlusal plane change and vertical control to achieve the forward rotation of mandible and the closure of anterior open bite at the same time. The transpalatal arch was used to enforce vertical control, and tongue crib was applied to inhibit tongue thrust and improve bilateral cross bite with dental compensation. Progressively, Chewies (Chewies™, Aligner Tray Seater, DENTSPLY International, USA ) exercise was applied to keep vertical control and train muscular activity with positive cooperation. Chewies exercise combined with Class III intermaxillary elastics achieves the movements of lower dentition and obtains the similar effect of multiple edgewise arch wire therapy.