Abstract
Although the effects of osteoporosis on the skeleton are well studied, site-specific and long-term studies on the mandible are still lacking. This study investigated the time-course changes of the bone microarchitecture in the mandibular condyle in comparison to the corresponding changes in the alveolar bone, body of the mandible, and femur. Thirty-six 11-week-old female Sprague-Dawley rats were divided into ovariectomized (OVX) (24 rats) and sham (12 rats) groups. The right femur and mandible were obtained from 6 OVX rats and 3 sham rats at 8, 12, 26, and 36 weeks after surgery, respectively. The histomorphometric analysis was performed using micro–computed tomography and histologic assessments from the (1) distal femur; (2) the alveolar bone and (3) the body of the mandible; (4) the subchondral and (5) the central region of the condyle. The Brown-Forsythe test was used to verify the assumptions for statistical analysis, and the Mann-Whitney U test was then performed. The mandibular condyle showed increased trabecular bone in both the OVX and sham groups, while the bone density was reduced in the distal femur and the mandible interradicular septum and body. When comparing the OVX group to the sham group, only the central condyle showed a significant reduction in bone density at 36 weeks. Osteoporosis behaves in different manners in different parts of the skeleton, and clinicians should be aware that patients displaying osteoporotic changes in the mandible are expected to show severely advanced bone mineral density reduction in other bones, such as the femur.
Highlights
For assessing osteoporosis in human beings, many researchers have attempted to predict systemic osteoporosis based on the mandibular cortex width shown in dental panoramic radiographs[6,7], because panoramic radiography is a commonly used modality and regular examinations are performed periodically on patients with little cost
There is no secure evidence for a link between mandible bone mineral density (BMD) and estrogen deficiency–induced osteoporosis, as Nicolielo and colleagues stated in their review paper[5]
This study showed that the BMD of the central condyle in the OVX group was slightly decreased at the last follow-up period, 36 weeks, while the sham group showed increase in the value
Summary
For assessing osteoporosis in human beings, many researchers have attempted to predict systemic osteoporosis based on the mandibular cortex width shown in dental panoramic radiographs[6,7], because panoramic radiography is a commonly used modality and regular examinations are performed periodically on patients with little cost. Panoramic radiography has limitations in assessing osteoporosis of the jaw, since the image www.nature.com/scientificreports/. The degree to which BMD decreases due to osteoporosis in the mandible and how it is related to other skeletal bones should be investigated first, before finding a method of predicting systemic osteoporosis from mandibular bone changes on panoramic radiography. A recent review article stated that limited evidence still exists regarding condyle resorption in response to estrogen deficiency–induced osteoporosis, with a paucity of controlled studies[5]. It is important from a clinical perspective to clearly characterize the associations of individual mandibular regions with systemic osteoporosis. Bone changes in multiple other regions of the mandible, including the mandibular alveolar bone and body, were compared to the corresponding changes in the distal femur
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