Quantitative assessment to the condylar chondrogenesis triggered by bite jumping appliance

Abstract

目的 考察咬合前導矯治器引發的下頜前伸導致的髁突軟骨改建及其與髁突骨改建的關系。方法 選取 1 0 0只同源雌性大鼠 ,分成 5組實驗組與 5組對照組。實驗組動物每日 2 4小時戴用咬合前導矯正器 ,使下頜前伸。實驗組與相應對照組動物分別在 3,7,1 4 ,2 1及 30天時處死并取材。采用最新的LeicaQwin5 5 0IW圖象處理系統來定量評價髁突軟骨各細胞層的面積變化。結果 (1 )髁突軟骨各細胞層面積隨下頜前伸而逐漸減少 ;(2 )移行層面積變化較明顯 ,在下頜前伸近 2 1天時該層充滿成骨細胞 ,第30天時已基本被新骨充盈。結論 以軟骨細胞減少為特征的髁突軟骨的改建是下頜前伸后髁突增生性改建的基礎。 Objective: This study was designed to quantify the chondrogenesis and its relationship with the bone remodeling in mandibular condyle under the condition of mandibular protrusion triggered by bite jumping appliance. Methods: One hundred SD rats with age of 5 weeks were selected and divided into 5 experimental groups (n=15) and 5 control groups (n=5). Animals in experimental groups were imposed with bite jumping appliance which caused identical magnitude of mandibular protrusion. The animals of experimental groups, together with their matched controls, were sacrificed 3, 7, 14, 21 and 30 days after the appliance insertion. Sections were cut from TMJ through sagittal plane and stained with H&E. The area of the chondrocytes in each zone of condylar cartilage was measured by using a computer-assisted image analyzing system( Leica Q 550IW) . Results: ( 1) The area of chondrocytes of all cartilaginous zones in experimental animals decreased more drastically than that in controls. ( 2) The erossive zone decreased gradually and was finally replaced by new bone at day 30. Conclusion: Chondrogenic alteration in condylar cartilage caused by bite-jumping appliance precedes the new bone formation in mandibular condyle.