顏面不對稱第三級異常咬合患者之正顎手術矯正治療效果評估-錐狀射束斷層掃描分析

目的: 對於嚴重的骨性第三級異常咬合患者,治療方式常需要合併矯正治療與正顎手術才能同時改善咬合功能及顏面外觀,過去對於治療效果的評估常使用二維影像放射線測顱分析。由於近年來錐狀射束斷層掃描的發展,使我們便於取得三維立體影像資訊。在本研究中,我們透過收集顏面不對稱之第三級異常咬合患者在接受正顎手術及矯正治療前後的錐狀射束斷層掃描資訊,分析治療前後三維影像的變化,以供日後診斷、擬定治療計畫、及改良相關術式之參考。實驗材料與方法: 本研究收集在台大醫院齒顎矯正科接受矯正合併正顎手術治療,於矯正治療前(T1)與所有治療結束並拆除矯正器後一個月內(T2)拍攝錐狀射束斷層掃描的第三級咬合異常患者共 15 位,使用 Dolphin imaging system 將治療前後之 CBCT 三維影像疊合在顱底後進行分析,包括前後、左右、垂直三個向度的測量。我們將三維形態解構至二維平面上,以評估左右向對稱性及前後向凹凸情形,二維平面包括四個水平面(平行法蘭克福平面,通過 T1 時的前鼻棘點(ANS,X1)、下顎正中門齒牙骨質牙釉質交界(L1 CEJ,X2)、右側頦孔(mental foramen,X3)、T2 時的骨性頦點(bony Pog,X4)之水平面)、九個矢狀面(正中矢狀面(Y0)往左右每距離一公分為下一個矢狀面,由右至左簡稱 YR4、YR3、YR2、YR1、Y0、YL1、 YL2、YL3、YL4)與五個冠狀面(通過 T2 bony Pog 的冠狀面(Z0)往後每距離一公分為下一個冠狀面,由前至後簡稱為 Z1、Z2、Z3、Z4、Z5),所有軟硬組織測量值都是在上述平面的交點來做記錄。 (一) 垂直方向 (1) 咬合平面:測量上顎左右第一大臼齒近心頰側咬尖最凸點至法蘭克福平面的垂直距離。 (2) 下顎垂直變化:在 Z3 以及 Z4 平面上,量測左右兩側下顎枝下緣最低點至法蘭克福平面的垂直距離,以評估左右差異程度在治療後是否有所改變。 (二) 前後方向在治療前與治療後軟硬組織三維形態表面,選取相對於四個水平面與九個矢狀面交點的結構點(需同時可以測量到軟硬組織,故共計 28 個),分別量測軟硬組織至冠狀參考平面(通過兩側 Porion 中點)的前後距離,以評估前後向之凹凸度變化。 (三) 左右方向在治療前與治療後軟硬組織三維形態表面,選取相對於三個水平面(X2、X3、 X4)與五個冠狀面交點的結構點,分別測量左右兩側對應點至正中矢狀面的垂直距離,以評估下顎之左右對稱性。結果: 十五位患者的在治療前上顎咬合平面傾斜程度平均為 1.73 mm,治療後則減少為 1.04 mm,其中接受雙顎手術(五位)與術前矯正時期有合併使用迷你植體(三位)的患者,左右側第一大臼齒有不同程度的 intrusion,其餘七位病患則多是 extrusion。治療前後大多數患者的左右下顎枝下緣高低傾斜方向與咬合平面傾斜方向一致,患者接受下顎 BSSO setback 手術之後下顎下緣大多有往下的移動,治療前左右高低落差平均為 1.87 mm,治療後增加為 2.08 mm。治療前所有患者前後方向上的左右臉凹凸度差異都是下顎大於上顎,於治療後下臉部皆變得較為對稱。五位接受雙顎手術患者的上顎軟組織相對於硬組織之移動比值由正中矢狀面往兩側,此比率有逐漸增加的趨勢(0.295、0.745、1.19); 至於下顎變化,十五位患者在下顎之軟硬組織移動比率於不同高度略有不同(X2、 X3、X4 level,分別為:0.96、1.07、1.13),但都非常接近 1。十五位患者中下顎較寬側與下巴偏移方向相同的 10 位病患,治療前下顎的左右寬度差異越往 Pog 處越明顯,治療後左右臉寬度差異變小,但仍未達到完全對稱。下顎軟組織相對硬組織的水平移動比值差異極大,並無一致性的結果。結論: 使用疊合之錐狀射束斷層掃描三維影像可以有效地分析下顎前突症患者之正顎手術矯正治療前後的軟硬組織變化。垂直方向上治療前後大多數患者的左右下顎枝下緣高低傾斜方向與咬合平面傾斜方向一致,治療後咬合平面傾斜程度較為輕微,但下顎枝下緣左右高低落差稍微增加。下顎前突症患者其下顎在前後方向上的左右不對稱情形較上顎明顯,接受雙顎手術之患者上顎軟組織相對硬組織之前後移動比值由正中矢狀平面往兩側逐漸增加,將單顎與雙顎手術一起評估則發現下顎於不同高度(L1 CEJ、mental foramen、Pog)的變化皆趨近於 1。顱顏面不對稱之下顎前突症患者下顎偏往左側的比例比右側高,下顎較寬側與下巴偏移方向相同之患者其左右寬度差異在 Pog 處最大,而下顎軟組織相對硬組織之水平移動比值個別差異很大,軟組織在水平方向的移動變化似乎是較難預測的。

關鍵字

錐狀射束斷層掃描；顏面不對稱第三級異常咬合；正顎手術；軟硬組織變化

並列摘要

Objective: The prevalence of Class III malocclusion is higher in Asians than in Caucasians. To improve the occlusal function and facial esthetics, orthodontic treatment combined with orthognathic surgery is often indicated in Class III malocclusion with severe skeletal discrepancy. The objectives of this research were to investigate the three-dimensional (3D) morphological changes of the soft and hard tissues in Class III facial asymmetry patients who were corrected with surgical orthodontic treatment. Method: The subjects included 15 adult skeletal Class III patients who had 3D cone beam computerized tomography (CBCT) taken before full mouth orthodontic treatment (T1) and within one month after debanding and debonding (T2). They were treated with orthodontic treatment combined with one-jaw surgery to setback mandible (bilateral sagittal split osteotomy, BSSO) or two-jaw surgery (Le Fort I maxillary advancement and BSSO mandibular setback). The 3D CBCT images were superimposed on the cranial base in Dolphin imaging system (best fit of cranial base). After superimposition, 3D changes of the soft and hard tissues were measured from the vertical, anteroposterior, and transverse directions, respectively. In addition, the soft to hard tissue movement ratios were calculated. Result: Asymmetry was more evident in the lower face in comparison with the middle face. Chin deviation was found in 13 of 15 subjects and 5 of them were deviated to the right side. Moreover, the mean deviation of bony pogonion at T1 was 4.32 mm. The mandibular prognathism were successfully corrected and facial asymmetry improved, but not fully corrected. In the vertical evaluation, the average occlusal plane canting changed from 1.73 mm to 1.04 mm. The vertical discrepancy of bilateral mandibular inferior border changed from 1.87 mm (T1) to 2.08 mm (T2). In the evaluations either before or after treatment, the vertical asymmetry of bilateral mandibular inferior borders was coincident with the direction of occlusal plane canting. In the anteroposterior (AP) evaluation of two-jaw surgery patients, the soft-to-hard tissue movement ratios (S/H ratios) of the maxilla gradually increased from midsagittal to paranasal area (0.295, 0.745, 1.19). The S/H ratios of the mandible were gradually increased from L1 CEJ to pogonion. Furthermore, marked individual variation of S/H ratios in transverse direction is noted. Conclusion: The CBCT 3D image is useful to evaluate the treatment effects of surgical orthodontic treatment in patients with mandibular prognathism and facial asymmetry. The S/H ratios of maxilla in AP direction gradually increased from midsagittal to paranasal area. The S/H ratios in mandible were close to one. The transverse movement of the soft tissue seemed difficult to predict from hard tissue because of marked individual variation.

並列關鍵字

cone beam computed tomography ； Class III malocclusion ； facial asymmetry ； orthognathic surgery ； soft and hard tissue changes

參考文獻

1. Singh GD. Morphologic determinants in the etiology of class III malocclusions: a review. Clin Anat. 1999;12(5):382-405.

3. Salonen L, Mohlin B, Gotzlinger B, Hellden L. Need and demand for orthodontic treatment in an adult Swedish population. European journal of orthodontics. Oct 1992;14(5):359-368.

4. Chew MT. Spectrum and management of dentofacial deformities in a multiethnic Asian population. The Angle orthodontist. Sep 2006;76(5):806-809.

5. McDonnell JP, McNeill RW, West RA. Advancement genioplasty: a retrospective cephalometric analysis of osseous and soft tissue changes. J Oral Surg. Aug 1977;35(8):640-647.

6. Hohl TH, Epker BN. Macrogenia: a study of treatment results, with surgical recommendations. Oral Surg Oral Med Oral Pathol. May 1976;41(5):545-567.

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顏面不對稱第三級異常咬合患者之正顎手術矯正治療效果評估-錐狀射束斷層掃描分析

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