多發特異性牙根吸收患者前牙開咬暨三級異常咬合之手術矯正治療－－病例報告

Surgical Orthodontic Treatment for a Class III Patient with Anterior Openbite and Multiple Idiopathic Root Resorption–A Case Report

牙根尖吸收是齒列矯正治療過程可能發生的後遺症之一，嚴重牙根吸收不僅影響牙齒穩定度，甚至可能導致牙齒無法負荷咬合力而需予以拔除。文獻回顧發現探討牙根吸收與矯正治療相關因素的研究相當多，然而目前仍未發現足以正確預測矯正治療中牙根吸收風險的決定性因素，主要原因是牙齒受力導致牙根吸收的易受性與表現嚴重度有相當大的個體差異。如果患者在矯正治療前即存在多發特異性牙根吸收，則此患者在接受矯正治療時發生牙根吸收的潛在風險可能較高。假若罹患多發特異性牙根吸收的患者因為骨骼性咬合異常，以致正顎手術介入是無法避免的治療選項，則其治療難度將大幅上升。本報告提出一位具上述問題的病例，此25歲女性患者主訴下巴歪斜及咬合不正，臨床檢查發現患者下顎前突及中臉部輕微後縮導致側面觀呈凹形輪廓，正面觀可見下巴明顯向右歪斜。口內咬合關係呈現上下前牙錯咬及開咬，而左右犬齒與臼齒皆為安格氏第三級咬合。測顱分析顯示其顱顏形態為骨性三級異常，主要問題為下顎骨前突合併輕微上顎骨後縮；環口X光片顯示全口齒列有多處牙齒呈現明顯牙根吸收，診斷為多發特異性牙根吸收。患者經過下顎後退手術合併全口齒列矯正治療後，顏面美觀及咬合功能都有大幅度改善。本報告將討論此多發特異性牙根吸收患者的治療過程及變化，並探討下顎前突合併前牙開咬的治療原則。

Severe root resorption with excessive tooth mobility may compromise the capability of the teeth to sustain occlusal loading, and possibly lead to extraction. Apical external root resorption (AERR) is considered as one of the risks associated with orthodontic treatment. Some clinical factors have been shown to correlate with orthodontic treatment, whereas the determinants for predicting AERR consistently were not found. Therefore, orthodontists must monitor the amount of root resorption during the course of orthodontic treatment. Multiple idiopathic root resorption (MIRR) is a rare condition. If MIRR is present, the severity of tooth mobility may get worsen during orthodontic treatment. The risk of AERR would be higher in these patients compared to regular orthodontic patients. Moreover, the condition of MIRR will increase the treatment difficulty and complexity in patients who require orthognathic correction of malocclusion. In this report, we present a 25 y/o female with facial asymmetry and mandibular protrusion. Her chief complaints were chin deviation, anterior openbite, and crossbite. The skeletal analysis revealed mandible prognathism and mild maxilla retrusion, which leading to concave facial profile. Severe MIRR was noticed in the panoramic radiograph taken for routine orthodontic examination. Full mouth orthodontic treatment combined with orthognathic surgery was indicated to resolve her malocclusion. To minimize the risk of root resorption possibly induced by the torque effect exerted from rectangular archwires, we used light round archwires throughout the course of pre-surgical orthodontic treatment. Though rectangular archwires were used to facilitate the placement of surgical hooks for inter-arch elastic traction after surgery, rectangular archwires were rounded specifically at slot sites. One-jaw surgery was conducted via bilateral sagittal split osteotomy for mandibular setback and slight counterclockwise rotation. Her facial esthetics and occlusal relationship were significantly improved. Occlusal stability was maintained at 1 year and 9 months follow-up.