关键词：应力；骨质疏松症；骨密度

　　【摘要】　目的　观察双侧卵巢切除(去势)(ovariectomy, OVX)大鼠下颌骨应力环境改变与下颌骨骨量的关系。方法　拔除大鼠右侧上颌全部磨牙，使咀嚼侧(左)、非咀嚼侧(右)下颌骨分别处于相对的高低应力环境中；利用去势手术(OVX)模仿绝经后骨质疏松症(postmenopausal osteoporosis)。依此将48只雌性大鼠分为4组：①OVX+拔牙组，②OVX+非拔牙组，③Sham-OVX(假去势)+拔牙组，③Sham-OVX+非拔牙组。在实验1.5个月和3个月时应用单光子骨密度仪对各组大鼠下颌骨双侧进行骨密度测量。结果　去势大鼠下颌骨骨量显著低于正常对照组大鼠(P＜0.05)。对于正常大鼠，在拔牙3个月时，低应力侧下颌骨骨量显著低于高应力侧(P＜0.05)，但它们与非拔牙对照组的差异均无显著性。对于去势大鼠，低应力侧下颌骨骨量显著低于高应力侧(P＜0.01)，在3个月时，低应力侧骨量显著低于OVX同期对照组(P＜0.05)，而高应力侧下颌骨骨量显著高于OVX同期对照组(P＜0.05)，但与Sham-OVX同期对照组比，仍显著偏低(P＜0.05)。结论　咀嚼功能可减缓雌激素低下所引起的下颌骨快速骨丢失，对于保持下颌骨骨量有一定的作用；而咀嚼功能低下或缺失则加重其骨丢失进程。因此，对于有骨质疏松症的患者，应尽早恢复其咀嚼功能。

The effects of local stress on bone mass of mandibles in ovariectomized rats

ZHOU Yongsheng, ZHOU Shumin, LI Guozhen, et al.

　　(Department of Prosthodontics, School of Stomatology, Beijing Medical University, Beijing 100081, China)

　　【Abstract】　Objective　To observe the relationship between the change of stress environment of mandibles and their bone mass in normal and ovariectomized(OVX) rats.Methods　 The high and low stress environment models of mandibles were established by unilateral maxillary molars extraction. The masticatory sides of the mandibles were regarded as the high stress sides and the non-masticatory sides were regarded as the low stress sides. Ovariectomized rats were utilized as postmenopausal osteoporosis models and Sham-ovariectomized(Sham-OVX) rats as control group. According to these ideas, 48 female rats were divided into 4 groups: 1)OVX+extraction group; 2)OVX+non-extraction group; 3)Sham-OVX+extraction group; 4)Sham-OVX+non-extraction group. The bone mineral densities(BMD) of all mandibles were measured by single-photon absorptiometry bilaterally 1.5 months and 3 months after extraction.Results　The mandibles of ovariectomized rats had lower BMD than those of normal rats(P＜0.05). To normal rats, the BMD of mandibles in low stress sides were lower than the high stress sides 3 months after extraction(P＜0.05), but the BMD of the two sides were not significantly different to those of the non-extraction control ones(P＞0.05). To ovariectomized rats, the BMD of mandibles low stress sides were much lower than the high stress sides(P＜0.01). The BMD of mandibles in low stress sides were much lower than non-extraction ones of OVX group after 3 months(P＜0.05). The BMD of the high stress sides were much higher than those of the non-extraction control ones of OVX group(P＜0.05), but they were still lower than those of the non-extraction control ones of Sham-OVX group(P＜0.05).Conclusion　The results indicate that the masticatory functions(the high stress environment) tend to conserve the mandibular bone mass in patients with systemic osteopenia such as postmenopausal osteoporosis and the masticatory deficiency(the low stress environment) tends to aggravate mandibular bone loss induced by systemic osteopenia. The masticatory functions should be rehabilitated for these patients as early as possible.

责任编辑：姚红祥