Abstract：
BACKGROUND: Aberrant occlusion and aging are two main risks for temporomandibular joint (TMJ) degeneration.
OBJECTIVE: To assess the combined impact of occlusion and age on TMJ disc.
METHODS: To avoid the confounding impact of gender, presently, 126 female C57BL/6J mice, 63 youngsters, 6-week old and 63 adults, 28-week old, were used. An experimental bilateral anterior crossbite (BAC) relation was created by installing metal tubes onto the mandibular incisors. Mice were sacrificed at 3, 7 and 11 weeks (n = 9). Additionally, the installed tubes were removed at 7 weeks in removal groups and the TMJs were sampled after another 4 weeks (n = 9). Disc changes were detected by histomorphology, immunohistochemistry, and western blot assays.
RESULTS: Disc deformation was obvious in BAC groups. The typical change was hyperplasia at the posterior region of the disc where there was significant infiltration of inflammatory cells. Expressions of the inflammatory markers, including tumour necrosis factor-α and interleukin-1β, and the catabolic markers, including fibronectin (FN), FN N-terminal fragments, and vascular endothelial growth factor-A, were all increased. The changes were more obvious in adults than in youngsters. Removal of BAC attenuated inflammatory and catabolic changes in the youngsters, but the inflammatory markers recovered little in the adults.
CONCLUSIONS: TMJ disc responds to BAC by degeneration and inflammation, and respond to BAC removal by rehabilitation. Adult discs show severer degeneration responses to BAC and a lower level of anti-inflammatory capability to BAC removal than the youngster\'s discs. Animals cannot be equated with humans. The human disc response to occlusion changes worth further exploration.
OBJECTIVE: To assess the combined impact of occlusion and age on TMJ disc.
METHODS: To avoid the confounding impact of gender, presently, 126 female C57BL/6J mice, 63 youngsters, 6-week old and 63 adults, 28-week old, were used. An experimental bilateral anterior crossbite (BAC) relation was created by installing metal tubes onto the mandibular incisors. Mice were sacrificed at 3, 7 and 11 weeks (n = 9). Additionally, the installed tubes were removed at 7 weeks in removal groups and the TMJs were sampled after another 4 weeks (n = 9). Disc changes were detected by histomorphology, immunohistochemistry, and western blot assays.
RESULTS: Disc deformation was obvious in BAC groups. The typical change was hyperplasia at the posterior region of the disc where there was significant infiltration of inflammatory cells. Expressions of the inflammatory markers, including tumour necrosis factor-α and interleukin-1β, and the catabolic markers, including fibronectin (FN), FN N-terminal fragments, and vascular endothelial growth factor-A, were all increased. The changes were more obvious in adults than in youngsters. Removal of BAC attenuated inflammatory and catabolic changes in the youngsters, but the inflammatory markers recovered little in the adults.
CONCLUSIONS: TMJ disc responds to BAC by degeneration and inflammation, and respond to BAC removal by rehabilitation. Adult discs show severer degeneration responses to BAC and a lower level of anti-inflammatory capability to BAC removal than the youngster\'s discs. Animals cannot be equated with humans. The human disc response to occlusion changes worth further exploration.
摘要：
背景：异常闭塞和衰老是颞下颌关节（TMJ）变性的两个主要风险。
目的：评估咬合和年龄对TMJ椎间盘的综合影响。
方法：为了避免性别的混杂影响，目前,126只雌性C57BL/6J小鼠，63名年轻人，6周龄和63名成年人，28周龄,被使用。通过将金属管安装到下颌切牙上，创建了实验性的双侧前牙咬合（BAC）关系。在第3、7和11周处死小鼠(n=9)。此外,在去除组中,在7周时将已安装的试管取出,在另外4周后对TMJ进行采样(n=9).通过组织形态学检测到椎间盘的变化，免疫组织化学，和蛋白质印迹分析。
结果：BAC组椎间盘变形明显。典型的变化是椎间盘后部区域的增生，其中有明显的炎症细胞浸润。炎症标志物的表达，包括肿瘤坏死因子-α和白细胞介素-1β，和分解代谢标记，包括纤连蛋白（FN），FN-末端片段,血管内皮生长因子A,都增加了。这种变化在成年人中比在年轻人中更明显。去除BAC减轻了青少年的炎症和分解代谢变化，但是成人的炎症标志物几乎没有恢复。
结论：TMJ椎间盘通过变性和炎症对BAC有反应，并通过康复来应对BAC移除。与年轻人的椎间盘相比，成人椎间盘对BAC的变性反应更严重，对BAC的抗炎能力水平较低。动物不能等同于人类。人类椎间盘对咬合变化的反应值得进一步探讨。
目的：评估咬合和年龄对TMJ椎间盘的综合影响。
方法：为了避免性别的混杂影响，目前,126只雌性C57BL/6J小鼠，63名年轻人，6周龄和63名成年人，28周龄,被使用。通过将金属管安装到下颌切牙上，创建了实验性的双侧前牙咬合（BAC）关系。在第3、7和11周处死小鼠(n=9)。此外,在去除组中,在7周时将已安装的试管取出,在另外4周后对TMJ进行采样(n=9).通过组织形态学检测到椎间盘的变化，免疫组织化学，和蛋白质印迹分析。
结果：BAC组椎间盘变形明显。典型的变化是椎间盘后部区域的增生，其中有明显的炎症细胞浸润。炎症标志物的表达，包括肿瘤坏死因子-α和白细胞介素-1β，和分解代谢标记，包括纤连蛋白（FN），FN-末端片段,血管内皮生长因子A,都增加了。这种变化在成年人中比在年轻人中更明显。去除BAC减轻了青少年的炎症和分解代谢变化，但是成人的炎症标志物几乎没有恢复。
结论：TMJ椎间盘通过变性和炎症对BAC有反应，并通过康复来应对BAC移除。与年轻人的椎间盘相比，成人椎间盘对BAC的变性反应更严重，对BAC的抗炎能力水平较低。动物不能等同于人类。人类椎间盘对咬合变化的反应值得进一步探讨。
