Bone Abstracts

Introduction: Mandibular alveolar bone appears to be particularly sensitive to local factors compared to other skeletal sites. In growing rats, occlusal hypofunction leads to a dramatic decrease of the alveolar bone microarchitecture. Intra-radicular bone surrounding teeth is a specific functional area with a high bone turnover. We hypothesized that the mechanical loading of the alveolar process during mastication may play a role in the preservation of the alveolar bone microarchitecture. The aim of this study was to compare mandibular bone with tibial bone microarchitecture in adult rats.

Material and methods: Nine 6-month-old female Sprague-Dawley rats (Janvier Lab, Laval, France) were used in this study as approved by the local animal ethics committee. MicroCT ex vivo analyses were performed with a Skyscan 1172 (Bruker, Kontich, Belgium). Classical bone parameters were assessed on the central region of the mandibular condyle, the interradicular alveolar bone of the first molar, and the secondary spongiosa in the proximal tibia.

Results: Trabecular bone volume increases respectively in the alveolar process (+44%, P<0.001) and in the condyle (+58%, P<0.001) compared to tibia. Trabecular number and thickness increase in both alveolar (respectively +15%,+38%, P<0.001) and condylar bone (respectively +22%,+50%, P<0.001) compared to tibia. On the other hand, trabecular separation decreases in alveolar and condylar bone (respectively −5%, −50%, P<0.001). Interestingly, bone marrow volume decreases in the alveolar (−36%, P<0.001) and in the condylar bone (−63%, P<0.001) compared to tibia.

Conclusion: Despite the fact that tibia and mandible are both submitted to mechanical loading, mandibular bone shows a more dense trabecular network than tibia. Present data suggest that mandibular bone is a unique skeletal-site submitted to specific regulations. Due to its particularly high trabecular density, it would be of interest to determine its response to usual pathological context such as osteoporosis, especially estrogen-deprivation in rats.