Abstract：
BACKGROUND: Mandibular malpositioning may result in an abnormal concentration of stresses within the temporomandibular joint (TMJ) in adult rats, which may further lead to a series of pathological changes, such as articular cartilage wear, subchondral bone sclerosis and osteophyte formation. However, the pathological and adaptive changes in condylar cartilage caused by different stress distributions are still controversial.
OBJECTIVE: The aim of this study was to observe the effect of sagittal changes in mandibular position on condylar cartilage by changing the occlusal vertical dimension (OVD) in adult rats.
METHODS: Fifteen-week-old female rats were divided into three groups: control (CON), increased OVD (iOVD) and loss of occlusion (LO) groups. An occlusal plate and tooth extraction were used to establish the animal model. TMJ samples of the experimental and CON groups were observed and investigated by bone morphological, histomorphological and immunohistochemical staining analyses at 3 days, 1 week, 2 weeks, 4 weeks and 8 weeks. Weight curves were plotted.
RESULTS: Micro-computed tomography showed that, compared with the CON group, cartilage destruction followed by repair occurred in both experimental groups, which was similar to the trend observed in haematoxylin-eosin staining. All experimental results for the iOVD group showed an approximately similar time trend. Compared with the iOVD group, the toluidine blue and immunohistochemical staining results in the LO group showed no obvious change trend over time.
CONCLUSIONS: Compared with occlusal loss, an increase in OVD caused faster and more severe damage to condylar cartilage, and subchondral bone repair occurred later.
OBJECTIVE: The aim of this study was to observe the effect of sagittal changes in mandibular position on condylar cartilage by changing the occlusal vertical dimension (OVD) in adult rats.
METHODS: Fifteen-week-old female rats were divided into three groups: control (CON), increased OVD (iOVD) and loss of occlusion (LO) groups. An occlusal plate and tooth extraction were used to establish the animal model. TMJ samples of the experimental and CON groups were observed and investigated by bone morphological, histomorphological and immunohistochemical staining analyses at 3 days, 1 week, 2 weeks, 4 weeks and 8 weeks. Weight curves were plotted.
RESULTS: Micro-computed tomography showed that, compared with the CON group, cartilage destruction followed by repair occurred in both experimental groups, which was similar to the trend observed in haematoxylin-eosin staining. All experimental results for the iOVD group showed an approximately similar time trend. Compared with the iOVD group, the toluidine blue and immunohistochemical staining results in the LO group showed no obvious change trend over time.
CONCLUSIONS: Compared with occlusal loss, an increase in OVD caused faster and more severe damage to condylar cartilage, and subchondral bone repair occurred later.
摘要：
背景：下颌骨错位可能导致成年大鼠颞下颌关节（TMJ）内的应力异常集中，这可能进一步导致一系列的病理变化，如关节软骨磨损，软骨下骨硬化和骨赘形成。然而,不同应力分布引起的髁突软骨的病理性和适应性改变仍存在争议。
目的：本研究的目的是通过改变成年大鼠的咬合垂直尺寸（OVD），观察下颌位置矢状面变化对髁突软骨的影响。
方法:将15周龄雌性大鼠分为3组:对照组(CON),OVD（iOVD）和闭塞丢失（LO）组。采用咬合板和拔牙法建立动物模型。对实验组和CON组的TMJ样本进行骨形态学观察和研究,3天的组织形态学和免疫组织化学染色分析，1周,2周,4周和8周。绘制重量曲线。
结果：微型计算机断层扫描显示，与CON组相比，软骨破坏后修复发生在两个实验组，这与苏木精-伊红染色观察到的趋势相似。iOVD组的所有实验结果显示出近似相似的时间趋势。与iOVD组相比，LO组甲苯胺蓝和免疫组织化学染色结果随时间无明显变化趋势。
结论：与咬合缺失相比，OVD的增加对髁突软骨造成了更快、更严重的损伤，软骨下骨修复较晚。
目的：本研究的目的是通过改变成年大鼠的咬合垂直尺寸（OVD），观察下颌位置矢状面变化对髁突软骨的影响。
方法:将15周龄雌性大鼠分为3组:对照组(CON),OVD（iOVD）和闭塞丢失（LO）组。采用咬合板和拔牙法建立动物模型。对实验组和CON组的TMJ样本进行骨形态学观察和研究,3天的组织形态学和免疫组织化学染色分析，1周,2周,4周和8周。绘制重量曲线。
结果：微型计算机断层扫描显示，与CON组相比，软骨破坏后修复发生在两个实验组，这与苏木精-伊红染色观察到的趋势相似。iOVD组的所有实验结果显示出近似相似的时间趋势。与iOVD组相比，LO组甲苯胺蓝和免疫组织化学染色结果随时间无明显变化趋势。
结论：与咬合缺失相比，OVD的增加对髁突软骨造成了更快、更严重的损伤，软骨下骨修复较晚。
