An immunohistochemical study on neovascularization in TMJ during mandibular advancement

Abstract

OBJECTIVE: Neovascularization is proved to be closely correlated with ossification. This study was designed to determine the biochemical path through which the new bone formation is enhanced in TMJ during mandibular protrusion. METHODS: SD Rats were fitted with bite-jumping appliances to allow for an adequate advancement of the mandible. The animals were sacrificed 3, 7, 14, 21 and 30 days, respectively, after placement of the appliances. Slides with TMJ tissue were prepared for biochemical procedure. Immunohistochemical approaches were adopted to examine neovascularization in TMJ by immuno-localizing the newly formed endothelial cells. Computer-assisted image analysis system was applied to quantify the positive immunoreaction. RESULTS: Neovascularization in connective tissue close to the condyle was 200% higher in the experimental groups than that in the control, and, within the bony tissue of the condyle, neovascularization in experimental animals was found to be 103% higher than that of the control. CONCLUSION: Increased neovascularization triggered by mandibular protrusion might intensify new bone formation in condyle and glenoid fossa and finally lead to a growth adaptation of TMJ to bite-jumping therapy.

目的依據顳下頜關節(TMJ)髁突軟骨內成骨及關節凹膜內成骨的生長模式,觀察TMJ在下頜前導位時的新生血管反應,在分子生物學水平探究新生微細血管增殖在TMJ骨組織改建中的作用。方法35天雌性Sprague-Dawly大鼠隨機分成5個實驗組和5個對照組。實驗組動物戴用咬合前導功能性矯正器(BJA),造成持續的下頜前導。實驗組和對照組動物分別在第3、7、14、21、30天時被處死。取下TMJ組織,石蠟包埋,切片,用于免疫組化分析。使用單克隆抗體EN7/44對新生血管內皮細胞進行免疫染色,評價新生血管形成。采用LeicaQwin圖像輔助分析系統,對新生血管進行定量分析。結果(1)連接髁突和關節窩后面的結締纖維組織中,標志新生血管的免疫染色實驗組比對照組平均高200%(P<0.01);(2)在髁突和關節窩骨組織的新生血管免疫染色中,實驗組比對照組分別高103%和163%(P<0.01)。結論下頜前導后TMJ軟硬組織內新生血管形成增多,這可能是導致TMJ新骨增加的重要機制之一。