Department of Oral Anatomy and Physiology and TMD, School of Stomatology, Fourth Military Medical University, 145 Changlexi Road, Xi'an 710032, China.
J Dent Res. 2013 Mar;92(3):253-9. doi: 10.1177/0022034512473482. Epub 2013 Jan 22.
The pathological changes of subchondral bone during osteoarthritis (OA) development in the temporomandibular joint (TMJ) are poorly understood. In the present study, we investigated the longitudinal alterations of subchondral bone using a rat TMJ-OA model developed in our laboratory. Changes in bone mass were examined by micro-CT, and changes in osteoblast and osteoclast activities were analyzed by real-time PCR, immunohistochemistry, and TRAP staining. Subchondral bone loss was detected from 8 weeks after dental occlusion alteration and reached the maximum at 12 weeks, followed by a repair phase until 32 weeks. Although bone mass increased at late stages, poor mechanical structure and lower bone mineral density (BMD) were found in these rats. The numbers of TRAP-positive cells were increased at 12 weeks, while the numbers of osteocalcin-expressing cells were increased at both 12 and 32 weeks. Levels of mRNA expression of TRAP and cathepsin K were increased at 12 weeks, while levels of ALP and osteocalcin were increased at both 12 and 32 weeks. These findings demonstrated that there is an active bone remodeling in subchondral bone in TMJs in response to alteration in occlusion, although new bone was formed with lower BMD and poor mechanical properties.
颞下颌关节（TMJ）骨关节炎（OA）发展过程中软骨下骨的病理变化知之甚少。本研究采用我们实验室建立的大鼠 TMJ-OA 模型，研究了软骨下骨的纵向变化。通过 micro-CT 检查骨量变化，通过实时 PCR、免疫组织化学和 TRAP 染色分析成骨细胞和破骨细胞的活性。从牙齿咬合改变后 8 周开始检测到软骨下骨丢失，并在 12 周达到最大值，随后进入修复阶段，直到 32 周。尽管在晚期骨量增加，但这些大鼠的机械结构较差，骨矿物质密度（BMD）较低。12 周时 TRAP 阳性细胞数量增加，而 12 周和 32 周时骨钙素表达细胞数量增加。12 周时 TRAP 和组织蛋白酶 K 的 mRNA 表达水平增加，而 12 周和 32 周时 ALP 和骨钙素的表达水平增加。这些发现表明，尽管新骨形成，但 BMD 和机械性能较差，TMJ 软骨下骨在咬合改变时存在活跃的骨重塑。
