正常顳顎關節之開閉口運動分析

Analysis of Normal Temporomandibular Joints During Open-Close Movement

陳健誌(Chien-Chih Chen)

指導教授 ： 呂東武 ； 陳韻之

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.02276

摘要

中文摘要

背景：

下顎運動學在現代牙醫學基礎中一直扮演著十分重要之角色，但是對其之理解多只侷限於顳顎關節髁頭而非整體之運動。雖然顳顎關節能同時進行旋轉及平移等運動的事實是早被確認的，但是直到近年來經由剛體力學引進這領域後，有關旋轉量計算之問題才逐漸獲得解決。由於對下顎運動之旋轉行為有更進一步的了解以後，利用顳顎運動立體描軌法的觀察作為基礎所得之若干傳統下顎運動學結論，逐漸地被發現有著嚴重的錯誤。

欲研究完整之下顎運動學，必須滿足六個自由度之要求，即沿著三個軸向平移之移動自由度及繞著三個軸向旋轉之旋轉自由度，需要複雜精密之測量硬體設備及高度的資料處理能力。如今在牙醫學領域中，結合光電子軌跡追蹤儀與剛體力學理論來記錄分析符合六個自由度之下顎運動，已成為其主流之研究方法。然而，如何置放目標標記來代表頭部與下顎在空間中座標系之標準作業程序卻尚未被建立，一些下顎運動表示之方法也尚未被證實。因此本次一系列之研究，其目的首先為最佳化Vicon 512®光電子運動追蹤儀在研究人類下顎運動學之使用方法，並藉由其成功地應用於人體其他主要關節之運算方法，來分析正常下顎之運動學行為。

材料、方法與結果：

五架百萬畫素(mega-pixel)解析度之Vicon 紅外線攝影機，以120赫茲(Hz)之取樣頻率，被用來擷取各個反光標記於實驗室廣義座標系統之位置。經過多次測試攝影機之佈置，建立了如下的測量環境：量測作業空間為50公分之正立方空間範圍，攝影機之空間解析度為0.0008公釐，絕對之系統測量誤差則小於0.4公釐。

皮膚標記之佈置:
為了減少穿越口腔之目標標記支架數以減少妨礙下顎正常生理運動之進行，我們使用皮膚標記來代表頭顱位置之座標系統。經過定量之比較得到以下之結果:
1. 位於上顏面部中線區附近之皮膚，有最小量之皮膚移動誤差。它们相對於黃金標準也就是連結上顎前齒區之目標標記的移動量，甚至較眼鏡目標支架上之標記要來得小。
2. 利用最佳化方法調整後，這些最少運動之皮膚標記的皮膚移動誤差可以被明顯地減少。
3. 若採用最少皮膚移動區域之皮膚標記加上最佳化之調整，它們所造成之誤差大致與系統量測誤差相當，已足以用來代表頭顱之位置。

平移與旋轉運動關係圖:
1994年Salaorni等學者提出之平移與旋轉運動關係圖，是一種簡易且具體之二維髁關節頭運動的描述方式。然而其方法論本身則尚未獲得驗證，也就是如下敘述:
1. 髁關節頭平移量描述，將因參考點選擇不同而有影響。不同之參考點將有不同關係圖之產生。
2. 倘若我們以平移與旋轉運動關係圖一次微分，也就是說單位角度之平移量與開閉口之角度關係來重新作圖，髁關節頭之運動行為將有戲劇化不同之特性。Salaorni等學者提出之五種型態之分類，也將因此被挑戰。

螺旋軸線(helical axis):
下顎螺旋軸線軌跡也被計算出來，同時該螺旋軸線與通過雙側髁關節頭之矢狀面交叉圖形也被提出說明。相對於髁關節頭相連軸線之平移與旋轉軌跡，螺旋軸線之方向與路徑就顯得更富戲劇性之變化，同時也更難以預期。而這些發現與其他主要關節螺旋軸線研究結果是相容的。

關鍵字

下顎 ； 光電攝影術 ； 運動學 ； 運動記錄

並列摘要

Abstract
The mandibular kinematics, which has been often represented by the condylar movement of the temporomandibular joint (TMJ), has played a crucial role in the foundation of the modern dentistry. Though the fact that the condyle could perform rotation and translation has been long recognized, the calculation of the amount of rotation hasn’t been solved till recently, after the introducing of rigid-body mechanics into this field. Since then, errors of the classical mandibular kinematics, which has been built based on the pantographic observations, were gradually disclosed. Unfortunately, an unbiased, clear, concrete conclusion of the normal mandibular kinematics is still lacking.

To study the mandibular kinematics completely, i.e. including 3 translational and 3 rotational degree-of-freedoms (DOF), needs sophisticated hardware and high data manipulation ability. Now combining the opto-electronic tracing devices and the rigid-body mechanics to record and analyze the 6 DOF mandibular movements has been gradually become the main-stream methodology in dentistry. However, the standard operating procedure of placing the markers to represent the head and mandible position in space hasn’t been established, yet. Some data presenting ways of the mandibular kinematics hasn’t been validated, either. The aims of these serial studies were therefore first to optimize the use of an opto-electronic tracking device, Vicon 512, to study the human mandibular kinematics, and second to analyze the motion data by using calculations successfully applied to other major human joints. The results would be compared with other analyses ever proposed in dentistry.

Instrument setup:
Five mega-pixel Vicon IR cameras were used to pick up the positions of markers within the global coordinating system with the temporal resolution of 120 Hz. The camera placements were optimized configured after several trials so the following working environments can be yielded:
Working volume: 50 cm x 50 cm x 50 cm
Spatial resolution: 0.0008 mm
Absolute system measuring error: < 0.4 mm

Skin marker placements:
In order to reduce the interfering of physiological movements by the trans-oral metal framework, the skin markers were used to represent the head position. After quantitative comparisons the following conclusions were obtained:
1. Skin areas near upper facial midline possessed least amount of skin movement. Their relative movements were even smaller than the optical frame by referencing to the gold standard, i.e. the clutch attached to the maxillay anteriors.
2. After the adjustment by applying the “Segmental Optimization Method” (S.OM.), the adverse effect of skin movement on these least mobile markers could be significantly reduced.
3. Skin markers could be used to represent the head positions while put on selective areas plus the S.O.M. adjustment. Their error was roughly equaled to the absolute system measuring error.

Translation/Rotation Diagram:
The translation/rotation diagram, which was proposed by Salaorni et al in 1994, is a concise description of condylar kinematics in 2D. However, the methodology itself hasn’t been validated. Namely,
1. The amount of condylar translation was reference-point dependent. Different condylar points would have different diagrams.
2. If we re-plotted the diagram by using the first order derivative of translation/ rotation vs. rotation, the kinematic behavior of the condyle would have dramatic different characters. The classification of 5 patterns proposed by Salaroni et al. was thus challenged.

Helical axis:
The mandibular helical axis was also calculated. The intersections of the helical axis on sagittal planes passing both side condyles were also presented. Contrast to the condylar trajectories, the orientations and paths of the helical axes changed dramatically and were hardly predictable. These findings were compatible with the helical axes of other major joints.

並列關鍵字

Movement recording ； Mandible ； optoelectronic ； kinematics

參考文獻

Cappozzo A, Catani F, Dellta CU, Leardini A (1995). Position and orientation in space of bones during movement: anatomical frame definition and determination. Clin Biomech 10:171-178.

Ferrario VF, Sforra C, Miani A, Serrao G (1992). Kinesiographic three-dimensional evaluation of mandibular border movements: A statistical study in a normal young nonpatient group. J Prosthet Dent 68:672-676.

Ferrario VF, Sforza C, Miani A, Serrao G, Tartaglia G (1996). Open-close movements in the human temporomandibular joint: dose a pure rotation around the intercondylar hinge axis exist? J Oral Rehabil 23:401-408.

Gibbs CH, Messerman T, Reswick JB, Derda HJ (1971). Functional movements of the mandible. J. Prosthet. Dent 26:604-620.

Gallo LM, Airoldi GB, Airoldi RL, Palla S (1997). Description of mandibular finite helical axis pathways in asymptomatic subjects. J Dent Res 76:704-713.