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顳顎關節(temporomandibular joint)是哺乳類動物咀嚼系統中的重要構造，關節盤(temporomandibular joint disc)則在顳顎關節的功能性活動中扮演著重要的角色。關節盤主要由膠原纖維所構成，許多學者認為咀嚼功能上的改變，將造成顳顎關節盤膠原纖維構造上的變化。臨床上常見後牙缺失(loss of posterior teeth)的情形。後牙缺失後咀嚼效率(chewing effi-ciency)變差，咬合關係與咀嚼功能也發生改變(如造成偏側咀嚼)，是否因而對關節盤中的膠原纖維排列產生影響，是值得探討的問題。
本研究以三十六隻大鼠為對象，分為三組，第一組剪除雙側後牙的臨床牙冠(clinical crown)，第二組剪除單側後牙的臨床牙冠，第三組為對照組，不做剪除臨床牙冠的處理。飼養五個月之後，取出大鼠顳顎關節盤。利用氫氧化鈉特殊處理技術(modified NaOH method)配合冷凍劈裂技術，在掃瞄式電子顯微鏡下，觀察後牙缺失對大鼠顳顎關節盤中膠原纖維或膠原細纖維(fibrils)排列的影響。
觀察關節盤之膠原纖維排列發現:在相同飼養條件下，經過相同飼養期後，三組大鼠顳顎關節盤上、下關節面中央部位之表層纖維排列，主要均為前後走向。相鄰的膠原細纖維束彼此交換部分的膠原細纖維，形成立體網狀結構。除了前後走向的纖維束外，還有少數疏鬆的膠原細纖維橫跨於前後走向的纖維束間。與中央處相比，周邊部份的膠原纖維排列顯得較為複雜，呈相互交叉的外觀。關節盤內部的膠原纖維走向與表面一致，來自內外兩側的膠原纖維在關節盤前端與後端處交叉。關節盤內部與表面的膠原細纖維亦均具有波浪狀起伏的構造。本研究的觀察結果顯示，關節盤之膠原纖維排列因應其所受的功能性刺激，為一穩定的立體網狀結構，在本研究之條件下，並不因剪除後牙之臨床牙冠而影響膠原纖維之主要排列。
Temporomandibular joint (TMJ) is one of the most complex joints of the body due to its intimate relationship with the dentition, muscles, and other oral structures. Temporomandibular joint disc (TMJ disc), as one of the basic elements of TMJ, plays an important role in the function of the TMJ. Disc mainly consists ofcollagen fibers. Some studies postulated that the alteration of the masticatory function will change the arrangement of the collagen fibers in TMJ disc. A lot of documents indicated that missing of posterior teeth might induce alterations of the occlusal function . The purpose of this investigation was to study the influence of posterior teeth loss on the arrangement of collagen fibers in discs of rats. Thirty six adult rats were ran-domly divided into three groups. Fifteen rats without removal of clinical crown were used as control (group C). Ten rats with re-moval of the clinical crowns of bilateral upper posterior teethwere designated as group B. Eleven rats with removal of unilat- eral upper and lower posterior teeth were designated as group U. Rats of each group were harvested after 5 months. Scanning electron microscope was used to study the collagen fiberar-rangement of the discs. By using the modified NaOH method in combination with the freeze-cracking method, fibrils on the superficial layer and fibrils in the internal structure with cellular components retained integrity could be observed.
The results indicated that the arrangement of the collagen fibers in the central area was mainly in anteroposterior direction, while that of the peripheral part was not tidy. The arrangement of collagen fibers in deep portion was in correspondence with that of the superficial portion. No obvious change in the collagen arrangement was found among these three groups. Within the limits of this study, we concluded that neither bilateral nor unilateral posterior teeth loss in the experimental rats caused a significant change in collagen fiber arrangement of discs.
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