The effect of aging on the nanostructure of murine alveolar bone and dentin

Alveolar bone, dentin, and cementum provide a striking example of structurally different collagen-based mineralized tissues separated only by periodontal ligament. While alveolar bone is strongly remodeled, this does not hold for dentin and cementum. However, additional dentin can be deposited on the inner surface of the pulp chamber also in older age. By investigating alveolar bone and molar of mice, the aim of our study is to detect changes in the mineral nanostructure with aging.

Buccal-lingual sections of the mandible and first molar from C57BL/6 mice of three different age groups (young 5 weeks, adult 22 weeks and old 23 months) were characterized using synchrotron small and wide-angle X-ray scattering. Local average thickness and length of the apatite particles were mapped with several line scans covering the alveolar bone and the tooth.

In alveolar bone, a spatial gradient was seen to develop with age with the thickest and longest particles in the distal part of the bone. The mineral particles in dentin were found to be become thicker, but then decrease of average length from adult to old animals. The mineral particle characteristics of dentin close to the pulp chamber were not only different to the rest of the tooth, but also when comparing the different age groups and even between individual animals in the same age group.

These results indicated that mineral particle characteristics were found to evolve differently between molar and alveolar bone as a function of age.