正顎手術前矯正對於三級異常咬合下顎前牙齒槽骨的影響 – CBCT研究

Effect of presurgical orthodontics on mandibular anterior alveolar bone in Class III malocclusion – a CBCT study

黃瀚民(Hann-Min Hwang)

指導教授 ： 陳羿貞

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201900964

摘要

目的：
嚴重骨性三級異常咬合患者接受正顎手術前去代償矯正過程中，下顎前牙的角度與位置改變，可能伴隨牙齦萎縮和齒槽骨流失。臨床上患者的齒槽骨、先天牙周組織條件可能因顱顏齒顎形態而異，去代償矯正牙齒移動可能對某些患者的下顎前牙齒槽骨形態造成更多威脅。本研究目的為探討下顎前牙齒槽骨形態經正顎手術前去代償矯正後的變化，並分析其中的影響因素。
研究程序及方法：
本研究蒐集接受矯正合併正顎手術治療的骨性三級異常咬合患者共計29位，患者根據下顎平面角大小不同分為三組。分別於治療前和正顎手術前拍攝錐狀射束電腦斷層掃描（CBCT），以CBCT結合數位齒顎模型，在個別齒軸的正中矢狀切面進行量測，完整記錄和分析嚴重骨性三級異常咬合患者下顎六顆前牙之齒槽骨形態特徵，比較不同顏面垂直顏面開展度之間是否有所差異；此外利用三維空間影像疊合，並進一步轉移治療前下顎咬合平面定位，分析去代償矯正治療後的牙齒位移與角度改變量，探討去代償矯正治療後齒槽骨的變化情形，並評估齒槽骨變化與牙齒移動改變量的關係，最後藉由混合模型多變項線性迴歸分析探討與齒槽骨厚度及高度變化有關之因素。
結果：
在不同顏面開展度的初始治療前齒槽骨形態比較中，三種齒位的唇側厚度都沒有顯著組間差異。在舌側厚度與齒槽骨整體厚度方面，三種齒位的低角組都顯著大於高角組。齒槽骨高度則只有舌側在三種齒位都有組間差異，高角組具有顯著最低的舌側齒槽骨高度。本研究試圖探究更細微的海綿骨與皮質骨變化的差異，結果只有舌側厚度有看到此二者明顯的組間差異。
觀察去代償矯正後的齒槽骨形態變化，三種齒位的整體厚度、舌側厚度和唇、舌側高度都呈現減少趨勢。低角組有較多的唇側海綿骨、唇側齒槽骨厚度增加量，及舌側海綿骨厚度減少量；但是在齒槽骨總厚度減少量或唇舌側高度減少量方面，顏面開展度不同的組間比較並未有顯著差異。三種齒位的牙齒移動量與齒槽骨形態改變並沒有顯著高相關性，而齒軸角度改變量則只有門牙的變化與唇、舌側厚度變化呈現顯著相關。
從多變項迴歸分析得知牙齒的齒位差異、治療前齒列凌亂嚴重程度、顏面開展度大小、以及去代償矯正牙齒角度改變量，以上都是與齒槽骨厚度變化有關之因素，而術前去代償矯正治療時間的長短則會影響齒槽骨舌側高度變化。
結論：
本篇研究證實顏面開展度顯著影響下顎前牙齒槽骨形態，高角組患者具有較狹窄的齒槽骨厚度和較低的齒槽骨高度，然而，去代償矯正的齒槽骨總厚度與高度變化量，在顏面開展度不同的患者之間，並無明顯差異。門齒唇舌向齒軸角度改變量與齒槽骨的唇、舌側厚度增減有關。回溯病例特徵與治療計畫的臨床因素，結果發現去代償矯正治療可能影響齒槽骨形態變化的五項顯著因素。對於需合併正顎手術之矯正患者，治療計畫擬定需兼顧齒列咬合及顏面美觀，齒槽骨與牙周健康更是不容輕忽，本研究將為精進臨床治療策略提供更多證據力及思考面向，未來可望輔以新興治療觀念技術，達成手術矯正的最佳治療成效。

關鍵字

骨性三級異常咬合 ； 去代償矯正 ； 齒槽骨形態 ； 垂直顏面開展度

並列摘要

Objective:
Retroclination of mandibular incisors is a frequent manifestation of dental compensation in the subjects with mandibular prognathism. In presurgical orthodontic treatment, labial tipping movement of mandibular anterior teeth for decompensation may induce alveolar bone loss in high-risk patients. The purpose of this study was to investigate alveolar bone change during presurgical orthodontic tooth movement performed in skeletal Class III patients.
Material and methods:
This study included initial and presurgical CBCT scans and dental models of 29 skeletal Class III patients treated with two-jaw orthognathic surgery. The subjects were divided into three groups representing different vertical facial divergency according to mandibular plane angle. By superimposing CBCT 3D images with digital dental models, change of alveolar housing was evaluated by the measurements of alveolar bone width and height on the individual mid-sagittal slice of six mandibular anterior teeth. Initial and presurgical images were superimposed to register the initial mandibular occlusal plane as the reference plane to assess the change of tooth position. In additional to vertical facial divergency, several dentition-related clinical parameters were recorded, and the mixed model multivariate linear regression was conducted to check the factors potentially affecting alveolar bone housing during presurgical orthodontics.
Results:
The lingual width (LW) and total widths (TW) of alveolar bone in the low-angle group were significantly wider than those in the high-angle group at all tooth sites including mandibular central and lateral incisors, and canine. As to buccal width (BW), no significant difference was noted among the 3 groups with different vertical facial patterns. The lingual heights (LH) of alveolar bone at all tooth sites were significantly shorter in the high-angle group compared to those in the low-angle group. In the width measurements differentially indicating spongious bone and cortical bone, only the lingual side showed significant difference.
The comparison of initial and presurgical data showed that the measurements of LW, TW, LH, and buccal height (BH) of mandibular anterior teeth were all reduced after dental decompensation regardless of facial divergency. The change of incisor axis was significantly correlated with the changes of BW and LW. According to the mixed model multivariate regression, different tooth site, initial irregularity index, facial divergency, and change of tooth axis were identified as the significant factors affecting alveolar bone width. Meanwhile, the duration of orthodontic treatment could affect the change of lingual alveolar height.
Conclusion:
This study substantiated that different facial divergency significantly affects alveolar bone morphology of mandibular anterior teeth. The alveolar bone width and height of mandibular anterior teeth were smaller in the high-angle patients in comparison to those in the low-angle patients. This study further revealed five factors affecting the alveolar bone height and width during presurgical orthodontic treatment in skeletal Class III patients.

並列關鍵字

Skeletal Class III malocclusion ； decompensation ； alveolar bone morphology ； facial divergency

參考文獻

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