功能性下颌偏斜对髁突软骨增殖活动影响的初步研究

Effects of mandible functional lateral shift on proliferation activity of condylar cartilage

目的:探讨功能性下颌偏斜对青春期大鼠下颌髁突软骨增殖活动的影响。方法:选用4周龄雄性SD大鼠80只,使用随机数字表法随机分成3组:偏斜组40只,偏斜恢复组20只,对照组20只。偏斜组及偏斜恢复组大鼠上前牙黏结冠套模拟功能性下颌偏斜。偏斜恢复组在安放冠套14 d后全部拆除,对照组不作任何处理。偏斜组及对照组分别在7、14、21 d及28 d各取10只与5只大鼠处死,偏斜恢复组在拆除冠套后的第7、14天各取10只大鼠处死。免疫组织化学SABC法检测下颌髁突软骨细胞增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)的表达。结果:(1)PCNA阳性细胞主要分布于髁突软骨增殖层和浅肥大层。(2)实验第7天时,偏斜组非偏斜侧髁突软骨中、后、外区域PCNA表达较对照组增强(中部P=0.022,后部P=0.019,外部P=0.024),偏斜侧髁突软骨后、外区域PCNA表达较对照组减弱(后部P=0.015,外部P=0.017),实验第14天差异更加显著(非偏斜侧中部P=0.0023,后部P=0.01,外部P=0.0097,偏斜侧后部P=0.0005,外部P=0.006),且差异性一直持续到第28天(非偏斜侧中部P=0.0001,后部P=0.0001,外部P=0.0001,偏斜侧后部P=0.0001,外部P=0.0001)。当拆除冠套后,偏斜恢复组两侧髁突软骨PCNA表达的差异逐渐减小,至实验28 d时恢复至对照组水平。结论:功能性下颌偏斜使青春期大鼠下颌骨双侧髁突软骨发生不对称适应性改建,而进行早期矫治后,双侧髁突软骨的生长改建活动逐渐趋于一致。

Objective：To study the effect of functional shift on proliferation activity of condylar cartilage among pubertal rats. Methods： Eighty Sprague-Dawley rats of 28 d were randomly divided into three groups：shift group（n=40）,recovery group（n=20）, control group （n=20）. Rats in shift and recovery groups were imposed with crowns on incisors causing mandible shift 2 mm to the left .The appliance was removed after 2 weeks in recovery group. Ten and five rats were killed on the 7th, 14th, 21st, 28th d separately in shift group and control group. Ten rats in recovery group were killed on the 7th and the 14th d after the crowns being removed. Proliferating cell nu- clear antigen（PCNA） expression was detected by immunohistochemistry. Results：（ 1 ）PCNA cells mainly distributed in the proliferat- ing cell layer. （2）On the 7th d,PCNA expression was increased in the posterior,central and external regions of the contralateral side in shift group（Pcentral=0.022,Pposterior=0.019,Pexternal=0.024） ;while it was significantly decreased in the posterior and external region of the ipsilateral side in shift group（Pposterior=0.015,Pexternal=0.017）. On the 14th d,the differences observed on the 7th d became more obvious （contralateral side：Pcentral=0.0023,Pposterior=0.01,Pexteral=0.0097;ipsilateral side：Pposterior=0.0005,Pexternal=0.006）and lasted to the 28th d. （contralateral side ：Pcentral=0.0001 ,Pposterior=0.0001, Pexternal=0.0001 ; ipsilateral side ：Pporsterior=0.0001, Pexternal=0.0001 ）. In recovery group, PCNA expression in all regions generally recovered to the level of the control group. Conclusions：The mandible functional shift in pubertal rats may cause asymmetric condyle remolding. Condyle remolding gradually recovers to normal in recovery group after early treatment.