牙齒齒槽代償機制在垂直方向的探討--高下顎平面角與低下顎平面角異常咬合患者的分析

The dentoalveolar compensatory mechanism in vertical direction: An analysis of patients of high-angle and low-angle malocclusion.

張文忠(Wen-Chung Chang)

指導教授 ： 陳光和 ； 姚宗珍

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.02408

摘要

在臨床經驗的印象中：長臉型、顏面開展度大的患者常易伴隨有前牙開咬；短臉型、顏面開展度小的患者則常易伴隨有前牙深咬。但也常可見到例外的情形：例如顏面開展度大的患者仍有正常的前牙水平及垂直覆蓋關係、甚至是深咬。針對不同的骨骼型態，牙齒會發生不等程度及方式的代償作用，以達到及維持上下齒列間的正常關係，進而提供較正常的功能。齒槽代償機制的方式有許多種—如牙齒的角度、高度及位置等。因此，本研究的主要目的是要分析在不同顏面開展度的骨骼型態下，探討齒槽代償機制在垂直方向所扮演的角色。研究方法是選取高顏面開展度及低顏面開展度的87位患者，分別描繪其測顱X光片。經影像處理程式讀取及計算後，分析各測量值間的對應關係。由於顏面形態是所有顱顏部骨骼的組成及表現，任何單一骨骼的大小或相對位置的改變皆會影響其他骨骼的表現。所以在分析顏面開展度時希望能有較整體的考量，而不是只由單一測量值來決定。因此在統計方法上我們使用主成分分析法 (Principal Component Analysis)，在長臉型組及短臉型組找到分別由8個及4個測量值所組成的有代表性的新變項 — 第一主成分 (1st principal component) 來代表所有顏面骨骼在垂直方向上的表現，他們在這兩個實驗組中的統計代表性分別達到99.05%和 99.52%。我們以overbite為應變項，骨骼型態及牙齒的高度和傾斜度為因變項，來分析比較其間的對應關係。得到結果如下：一. 在長臉型、顏面開展度大的這組 — (1)顏面骨骼的開展度和overbite有統計上的顯著相關性，亦即長臉型的較易有前牙開咬的傾向 (2)齒槽代償機制主要是發生在牙齒的高度而與牙齒的傾斜度無關 (上顎臼齒及下顎門齒的高度)。二. 在短臉型、顏面開展度小的這組 — (1)顏面骨骼的開展度和overbite沒有統計上的相關性，亦即短臉型的不一定有前牙深咬的傾向 (2)齒槽代償機制主要是發生在門齒而與臼齒無關 (上顎門齒及下顎門齒的高度和傾斜度)。

關鍵字

代償機制 ； 主成分分析法

並列摘要

Most of the clinicians have the impression that the long-faced, hyperdivergent patients are easily accompany with anterior open bite; and the short-faced, hypodivergent patients are easily accompany with anterior deep bite. But there are exceptions sometimes. For example, the hyperdivergent patients have normal incisal relationships in both horizontal and vertical directions. Further more, deep bite could be seen in this kind of skeletal pattern occasionally.
A hypothesis offered here to explain the variations of the overbite is that there exists a system which attempts to maintain normal interarch relations under varying jaw relationships. This is the so called " dentoalveolar compensatory mechanism". If the compensation works, we could see normal bite in hyperdivergent patients. If the compensation is poor, then we would see open bite in the same patient. The compensatory mechanism is operated to coordinate the eruption and position of the teeth relative to their jaw bases in order for a normal relationship between upper and lower dental arches to be achieved and maintained.
Therefore, the aim of this study was to analyze the dentoalveolar compensatory mechanism under extreme skeletal patterns in vertical direction. Lateral cephalometric roentgenograms of 87 adult patients with hyperdivergent and hypodivergent skeletal patterns were selected from the database of Orthodontic Department of National Taiwan University Hospital. After progressing and calculating by the "Cephalogram Analysis System" image software, the data of skeletal-vertical (SV), dental height (DH), dental inclination (DI) and overbite (OB) were obtained.

Because the study focus is for the skeletal-vertical (SV) variables that has 22 measures, the first step was to reduce the size of the SV variables and would not compromise their statistical value in the meanwhile. We applied stepwise regression and stepwise logistic regression 2 methods. After these procedures, 8 characteristics variables --- A-Gn, N-Go-Gn, PFH/AFH, OP-MP, FH-SGn, Ar-Go, UAFH/LAFH, A-Ar-Gn were found in the high angle groups. And 4 characteristics variables --- FH-SGn, ArGo-FH, A-Gn, N-Go-Ar were found in the low angle groups. Thus we obtained 2 new variables, LONGSV and SHORTSV, to represent the performance of all skeletal variables in vertical direction for the high angle groups and low angle groups respectively from the principal component analysis. And the cumulative percentages of the 1st principal component are as high as 99.05% for the high angle subjects and 99.52% for the low angle subjects. Then, the multiple regression analysis was used to test which variables( SV, DH, DI ) made a significant contribution to the estimation of overbite. The results of our findings are summarized in the followings:
1. In high-angle patient group, there is a significant correlation between the skeletal divergency and the anterior overbite. That is to say, the high-angle patients have the tendency of anterior open bite. And the dentoalveolar compensation depends on the dental height ( upper molar & lower incisor ) not the dental inclination.
2. In low-angle patient group, there is no significant correlation between the skeletal hypodiergency and anterior deep overbite. So the deep bite is caused by dental portion mostly, and it is more affected by the anterior teeth than the posterior teeth.

並列關鍵字

compensation ； principal component analysis

參考文獻

Bjork A. Prediction of mandibular growth rotation. Am J Orthod 1969; 55: 585-99.

Bjork A, Skieller V. Facial development and tooth eruption – An implant study at the age of puberty. Am J Orthod 1972; 62: 339-83.

Burstone CJ. Deep overbite correction by intrusion. Am J Orthod 1977; 72: 1-22.

Cangialosi T. Skeletal morphologic features of anterior open bite. Am J Orthod 1984; 85: 28-36.

Chang YI, Moon SC. Cephalometric evaluation of the anterior open bite treatment. Am J Orthod Dentofacial Orthop 1999: 115: 29-38.