骨性二級異常咬合合併下顎後縮者齒顎顏面形態測量學的探討

The Dentofacial Morphometry of Skeletal Class II Malocclusion with Mandibular Retrusion

林昱均(Yu-Chun Lin)

指導教授 ： 張宏博

高雄醫學大學/口腔醫學院/牙醫學研究所/碩士(2008年)

摘要

骨性二級關係佔了人口的百分之十五至二十左右，這種變樣產生顏面外觀上一些特殊的表徵，其中又以下顎骨後縮最為常見。下顎後縮是安格氏二級異常咬合的原因之一，也是常見的顏面形態問題。在治療上，如何提供患者一個良好的功能及美麗的外觀，都是一種極大的挑戰。由於多數的研究結果都受到年齡選擇上的影響，因此常伴隨著生長發育帶來的一些顱顏形態改變。因此研究已生長完成的顱顏形態對於臨床上治療有特別的意義及價值。
本篇研究的目的為探討國內成年骨性二級異常咬合合併下顎後縮者齒顎顏面形態之特徵。比較80名骨性二級異常咬合合併下顎後縮（∠ANB > 5°, ∠FNB < 86°）的成年人與80名正常咬合成年人的側面測顱放射線圖。共採35個標記點，描繪後利用數位板輸入電腦。測顱形態分析共包括30項線段、29項角度、4項比值。進行測顱項目的單變項及多變項分析（MANOVA）。其中，單變項分析有額外針對性別因子及咬合因子分別做2-Way ANOVA，而多變項分析也有考量性別因子。
結果如下：骨性二級異常咬合合併下顎後縮者並非單一的表徵，可由許多異常骨骼牙齒因素的組成產生。（1）顱底形態分析：下顎後縮異常咬合者有較長的前顱底，但顱底角及鞍角與正常咬合者無異。（2）上下顎相對於顱底之水平關係：下顎後縮異常咬合者有較長的上顎骨，但是上顎骨相對於顱底來說並沒有前突的現象。下顎骨方面，下顎骨長度則是呈現較短及較小的情形，下顎枝前後緣寬度則可能因代償性生長而有變寬的情形，但下顎相對於顱底而言呈現較後縮的現象。（3）上下顎相對於顱底之垂直關係：上顎平面、下顎平面、下顎枝平面及咬合平面較傾斜；前顏面高度較大（上前顏面高度及下前顏面高都都偏大）、後顏面高度偏小（下顎枝較短），顏面展開度有較大的情形，下顎骨朝順時鐘方向旋轉。（4）上下顎門齒的相對關係：上顎門牙的傾斜度正常並且有過度萌發的情形。下顎門牙朝唇側傾斜，並且有過度萌發的情形。上下顎門牙長軸交角較小，門牙間水平覆咬較大，垂直覆咬較深。（5）上下顎第一大臼齒相對關係：上顎第一大臼齒向近心傾斜，並且有過度萌發的情形。下顎第一大臼齒位置方面，男女性都有向近心傾斜、較後縮及過度萌發的情形。
成年男性與女性骨性二級異常咬合合併下顎後縮者顱顏齒顎形態，在我們的樣本中除了有大小不同的差距，另外在整體的表現上也有性別的差異，因此我們認為本研究存在兩性二形（sexual dimorphism）的情況。
本研究尚未進行顱底、上顎、下顎幾何形態學之分析，若能找出個別差異對於臨床上的診斷與治療計畫訂定是有其重要性的。

關鍵字：骨性二級異常、下顎後縮、測顱分析

關鍵字

骨性二級異常 ； 下顎後縮 ； 測顱分析

並列摘要

Skeletal Class II malocclusion is a facial alteration that affects about 15% ~ 20% of the population. This type of discrepancy brings about modifications in the skeletal profile and the type of mandibular retrusion is the most popular skeletal pattern in Skeletal Class II facial pattern. As to the treatment, providing a good functional occlusion and a proper esthetics is a great challenge for the orthodontist. Most results from previous researches included age as an influential factor. The craniofacial pattern changes as one grow. Therefore, a different study on non-growing patients is advantageous in providing better diagnosis and treatment clinically.
Because of that, the aim of this study was to investigate the morphological characteristics of the craniofacial pattern in adults with Skeletal Class II malocclusion with mandibular retrusion. Lateral cephalograms of 80 adults with Skeletal Class II malocclusion with mandibular retrusion (∠ANB > 5°, ∠FNB < 86°) compared with 80 adults with normal occlusion. Thirty five landmarks were identified and digitized. Cephalometric analysis utilizing 30 linear, 29 angular and 4 ratios measurements were under taken. Statistical comparison of the two groups was performed with Student’s t-test, 2 way-ANOVA (adjusted by occlusion and gender) and MANOVA (adjusted by gender).
The results are as follows: Multiple variations of skeletodental features were found for Skeletal Class II malocclusion with mandibular retrusion. (1) Morphometry of cranial base: The samples with mandibular retrusion had longer anterior cranial length but the internal base angle and saddle angle are not different from the normal occlusion. (2) Skeletal horizontal relationship: The samples with mandibular retrusion had longer maxillary length but the maxilla is in normal position related to the cranial base. The mandible is more retrusive and the morphology is smaller than normal occlusion but the ramus width is wider than normal occlusion may because of the compensative growth. (3) Skeletal vertical relationship: The samples with mandibular retrusion had more tilting maxillary plane, mandibular plane, ramus plane and occlusal plane. The samples had longer total anterior facial height, longer upper and lower anterior facial height and shorter posterior facial height (shorter ramus height) than normal occlusion. Otherwise hyperdivergent facial pattern was noted and the mandible was rotated clockwisely. (4) Upper and lower incisor relationship: The samples of mandibular retrusion had extrusive but normal inclined upper incisors, more proclined and extrusive lower incisors, larger inter-incisal angle, larger overjet and deep overbite. (5) Upper and Lower 1st molar relationship: In mandibular retrusion male and female had more mesial tipping and more extrusive upper 1st molars. Besides, both male and female had more mesial tipping, more retrusive and more extrusive lower 1st molars.
The dentofacial characters of Skeletal Class II malocclusion with mandibular retrusion in our samples, there were not only the different size between sex but also the whole appearances. Because of that we defined there was sexual dimorphism in our samples
In this study, we had not yet analyzed the geometric morphometric analysis for cranial, maxilla and mandible individually. One believes that the cognitive of individual difference will be helpful in making future diagnosis and treatment in clinically.

Key words: Skeletal Class II relation, Mandibular retrusion, Cephalometric analysis

並列關鍵字

Skeletal Class II relation ； Mandibular retrusion ； Cephalometric analysis

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