以骨性錨定裝置治療後天開咬患者之療效評估

Abstract

目的： 前牙開咬在矯正領域中為一種非常具有挑戰性之不正咬合類型，而前牙開咬之病患中有一族群其前牙開咬之成因來自於顳顎關節障礙(temporomandibular joint disorder)，這類病人的咬合面具有過去磨耗的痕跡，顯示曾經有過咬合接觸，因此將這類不正咬合特稱為後天開咬(acquired openbite)。後天開咬之病患不僅有咬合功能及咀嚼效率受損之現象，顏面外觀上也呈現下顏面長度增長，下顎後縮，下顎骨角增大之情形。傳統治療方式主要以前牙挺出之方式關閉前牙開咬，對於病患之顏面外觀沒有改善效果，唯有接受正顎手術方有機會同時改善咬合功能及顏面外觀。近年來由於迷你植體的蓬勃發展，開始將迷你植體應用於治療前牙開咬，可造福程度較輕微或對正顎手術存有疑慮之病患。然而過去的研究鮮少具有顳顎關節障礙的明確診斷，也缺少觀察咬合改正後顳顎關節狀況的文獻。 因此本篇研究致力於探討迷你植體對於前牙開咬非手術性治療的效益及穩定度，並搭配核磁共振造影了解顳顎關節之情形，評估此治療方式對於病患顱顏型態的改變及呼吸道的變化。期盼為後天開咬病患的非手術性治療建立診斷、治療及維持治療後成果的標準程序。 實驗材料與方法： 本研究分為前瞻性及回溯性研究兩部分。 前瞻性研究對象為七位後天開咬之女性患者，於臺大醫院顳顎關節障礙門診治療追蹤至無顳顎關節障礙及疼痛之臨床表徵，並以臨床檢查、咬合板及核磁共振造影確認顳顎關節病程穩定後病患方可接受齒顎矯正治療。治療方式為骨性錨定裝置輔助矯正治療。待病患有前牙接觸後將給予病患問卷分析治療前後之主觀感受並接受核磁共振造影以分析顳顎關節狀況。 測顱分析部分將加入回溯性研究之樣本，對象為於台大齒顎矯正科以骨性錨定裝置輔佐矯正治療以關閉後天開咬之患者以增加統計分析之可信度。測顱分析之樣本共計24位病患。將以相依樣本t檢定比較治療前後之測顱分析數值。 結果： 所有病患在治療後均得到前牙水平及垂直覆咬之顯著改善，核磁共振造影多無顳顎關節發炎之表現。測顱分析於治療後觀察到上顎後牙齒顎高度減少、下顎平面角減少、顏面高度減少並且呼吸道寬度增加之情形。 結論： 骨性錨定裝置輔助矯正治療可藉由上顎後牙壓入造成下顎骨逆時針方向旋轉以關閉前牙開咬並達到改善顏面外觀的效果，為後天開咬之患者提供了非手術性治療的選擇。惟其長期穩定度尚需進一步研究分析。

Objectives： Anterior openbite was probably the most challenging type of malocclusion among the orthodontic field. Certain amount of this malocclusion was attributed to temporomandibular joint disorder. These patients often exhibited attrition facet over the occlusal surface and loss of mamelon over the incisal edges, suggesting they had occlusal contact during the previous years. As a result, we further classified this kind of malocclusion as “acquired openbite”.The patient with acquired openbite not only suffered from compromised occlusal function and chewing efficiency, but also concerned about the worsened facial appearance. They often had increased lower facial height, retrusive chin and increment in the mandibular plane angle. The traditional orthodontic mechanism could only achieve anterior teeth extrusion. By that way, we could not improve the facial esthetics of the patient. Only receiving orthognathic surgery can both the occlusal function and facial esthetics be improved concomitantly. In the recent years, as the rapid development of temporary anchorage devices (TADs), offering the practitioners a different way for treating anterior openbite. Molar intrusion via TADs was a valid alternative for those patient who had less severity or rejected surgical treatment protocol. However, there was no definitive diagnosis of the temporomandibular joint disorder in the previous literatures, nor follow up study after the bite closing. Therefore, the objective of this study is to elucidate the benefit of this new method for treating acquired openbite ,verify its stability and evaluate the alteration in the skeletal facial pattern and the dimension of airway. We also use MRI as a conjunctive tool to justify the condition of the temporomandibular joint area. Materials and methods： Our study comprised both the prospective and retrospective design. The prospective study sample included 7 females with acquired openbite receiving treatment at the TMD department,NTUH. Orthodontic treatment started after the symptoms and signs of TMD subsided and the TMJ condition stabilized. The patients received orthodontic treatment with TADs for bite closure. The questionnaire and MRI examination were performed after positive overbite achieved. The cephalometric analysis included both the prospective and retrospective samples to achieve better statistic power. The retrospective samples were the acquired openbite patients received orthodontic treatment with TADs for posterior intrusion. The differences between pre-treatment and post-treatment cephalometric measurements were analyzed by the pair-t test. Results： All patients achieved improved overjet and positive overbite after the treatment. The MRI showed no inflammatory sign after bite closing. The paired-t test revealed decreased upper posterior dental height, decreased mandibular plane angle, decreased facial height and increased airway dimension after bite closing. Conclusion： Orthodontic treatment in conjunction with TADs could achieve upper posterior teeth intrusion thus eliminating the mandibular plane angle. The counter-clockwise rotation of the mandible not only corrected the anterior openbite but also improved the chin projection. As a consequence, posterior teeth intrusion via TADs could be a valid alternative treatment protocol for patients with acquired openbite.