Age‐dependent changes of the mandible bone throughout the lifespan in female F344/N rat |
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Authors: | Kazutoshi Nishijima Tamio Ohno Ryoichi Saito Yasunori Sumi Hiroaki Aoyama Shin Tanaka |
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Affiliation: | 1. Animal Research Laboratory, Bioscience Education‐Research Support Center, Akita University, Akita, Japan;2. Animal Facility for Aging Research, National Institute for Geriatrics and Gerontology, Obu, Japan;3. Laboratory Animal Science, Division of Experimental Animals, Graduate School of Medicine, Nagoya University, Nagoya, Japan;4. The Primate Research Facility, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Japan;5. Center of Advanced Medicine for Dental and Oral Diseases, National Center for Geriatrics and Gerontology, Obu, Japan;6. Toxicology Division, Institute of Environmental Toxicology, Joso, Japan |
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Abstract: | Age‐dependent changes of the mandible bone in female F344/N rats, aged 22–1196 days, were analyzed using physiological bone properties and morphology. Bone weight, bone area, bone mineral components, and bone mineral density were assessed using dual‐energy X‐ray absorptiometry. The bone weight, bone area, bone mineral components, and bone mineral density increased rapidly until approximately 150 days of age, increased gradually thereafter, and then stabilized or decreased after 910 days of age. The ratio of bone mineral components to bone weight (bone mineral ratio) increased rapidly until approximately 43 days of age and stabilized thereafter. Size of the mandible, which was measured at 13 points on mandible surface, increased with age, and the rate of change showed a similar pattern to the other parameters. From a principal component analysis on morphometric measurements, principal component 1 (size factor) increased proportionally with age, whereas principal component 2 (shape factor) decreased until approximately 88 days of age and then increased after 365 days of age. As a result, the scatter plots for principal component 1 and principal component 2 were V‐shaped, which indicates that the mandible developed in size, with deformation at younger ages, and recovered its original shape later in life. Our results revealed the occurrence of inflection points at approximately 43, 88, 150, 365, and 910 days of age. Some of these ages corresponded to transition points revealed by the age‐dependent changes of the occlusal mandibular condyle and tooth wear in the same rat. |
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Keywords: | aging change bone mineral F344/N rat mandible bone morphometry |
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