Postmenopausal osteoporosis causes severe loss of bone quantity and quality in limb bone but has a lesser effect on jaw bone. Thus, the objective of this study was to examine whether ovariectomy (OVX) and mastication alter the regional variation of jaw bone characteristics. Sprague-Dawley female rats (6 months) were given a bilateral OVX or a sham operation (SHAM) (n = 10 for each group). After 2 months post-OVX, the hemi-mandible from each rat was dissected. A micro-computed tomography based mean, standard deviation (SD), the lower and upper 5th percentile (Low₅ and High₅) values of tissue mineral density (TMD) histograms were assessed for whole bone (WB), alveolar bone (AB), cortical bone (CB), and trabecular bone (TB) regions. Morphology of TB and periodontal ligament (PDL) was also obtained. Layers of AB were segmented up to 400 μm from the PDL. Mechanical properties at the tissue level were measured by nanoindentation at the same site by a single loading-unloading cycle of indentation in hydration. The AB and TB regions had significantly lower TMD Mean, Low₅, and High₅ but higher SD than the CB region for both sham and OVX groups (p < 0.01). TMD parameters of the OVX group rapidly increased up to 60 μm away from the PDL and were significantly higher than those of the sham group starting at 280 μm and farther in the CB region (p < 0.05). All values of morphological and nanoindentation parameters were not significantly different between sham and OVX groups (p > 0.06). Estrogen deficiency induced by OVX did not deteriorate bone characteristics including mineral density, morphology, and nanoindentation parameters in rat mandibles. Masticatory loading had an effect on the TMD parameters at the limited region of AB. These results provide insight into why osteoporosis-associated jaw bone fractures are extremely rare.

绝经后骨质疏松症会导致四肢骨的骨量和质量严重下降，但对颌骨的影响较小。因此，本研究的目的是检查卵巢切除术 (OVX) 和咀嚼是否会改变颌骨特征的区域变异。Sprague-Dawley 雌性大鼠 (6 个月) 被给予双侧 OVX 或假手术 (SHAM) (每组 n = 10)。OVX 后 2 个月后，解剖每只大鼠的半下颌骨。基于平均值、标准偏差 (SD)、下和上 5 个百分位数（低₅和高₅）的微型计算机断层扫描) 评估全骨 (WB)、牙槽骨 (AB)、皮质骨 (CB) 和小梁骨 (TB) 区域的组织矿物质密度 (TMD) 直方图值。还获得了 TB 和牙周膜 (PDL) 的形态。AB 层从 PDL 分割到 400 μm。组织水平的机械性能通过在水合中压痕的单个加载-卸载循环在同一部位进行纳米压痕测量。AB 和 TB 区域的 TMD 平均值、低₅和高₅显着较低但假手术组和 OVX 组的 SD 均高于 CB 区域（p < 0.01）。OVX 组的 TMD 参数在距 PDL 60 μm 处迅速增加，并且在 CB 区域从 280 μm 开始显着高于假手术组（p < 0.05）。假手术组和 OVX 组之间的所有形态学和纳米压痕参数值均无显着差异（p > 0.06）。OVX 诱导的雌激素缺乏不会使大鼠下颌骨的骨骼特征恶化，包括矿物质密度、形态和纳米压痕参数。咀嚼负荷对 AB 有限区域的 TMD 参数有影响。这些结果提供了为什么骨质疏松症相关的颌骨骨折极为罕见的见解。