Analysis of Biological Apatite Orientation in Rat Mandibles

Abstract

Recently, significant progress has been made in medical techniques for regenerating bone. However, bone evaluation techniques generally assess bone quantity as opposed to bone quality. The use of c‐axis crystallite orientation of biological apatite (BAp) as a bone quality index has recently generated great interest. BAp demonstrates strong crystallographic anisotropy, and preferential alignment of BAp in each bone varies depending on the shape and stress conditions in vivo. In the mandible, complicated bone shape and stress conditions in vivo might be associated with both bone quantity and quality. In this study, we aimed to elucidate changes in the bone microstructure in the mandible using crystallographic orientation of BAp as a bone quality index. Using Crj : CD (SD) IGS female rats, we observed changes in the dentulous mandible during bone growth. Measuring points on the mandible were determined based on its positional relationship with the teeth. For analysis of bone quantity, the area and bone mineral density of cortical bone were evaluated using peripheral quantitative computed tomography (pQCT), while the orientation of the BAp c‐axis, as analyzed by a micro‐beam X‐ray diffraction system, was used to assess bone quality. The results of both bone quantity and quality assessments indicated that changes during bone growth varied depending on the presence of teeth. We concluded that the microstructure (especially the texture) of BAp crystallite changes in correlation with variations in stress distribution in vivo resulting from changes in chewing conditions designed to optimize the dynamic chewing function.

The osseointegration stimulatory effect of macrogeometry‐modified implants: a study in the rabbit

“…This load‐dependent HA alignment has been reported by Nagisa et al. () that the biological apatite (BAp) forms in correlation with variations in stress distribution. In their study, the BAp in the bone formed differently depending on the force they bare.…”

Analysis of Biological Apatite Crystal Orientation in Anterior Cortical Bone of Human Mandible Using Microbeam X-ray Diffractometry

“…Differences in the respective susceptibilities of BMD and BAp crystal orientation to local stress may explain this independence. 16,26) In comparison to BMD, BAp crystal orientation demonstrated more prominent localized effects of dentition.…”

Alignment of Biological Apatite Crystallites in Peri-Implant Bone of Beagles

“…Nakano et al demonstrated through experiments in monkey jawbones that the BAp crystallite basically aligns in the mesiodistal direction of the long axis, but reported that the crystallite aligns in the direction of occlusal pressure as a result of masticatory pressure in the vicinity of teeth 19) . Meanwhile, Nagisa et al examined BAp crystallite alignment in the alveolar and basal regions of rat jawbones, while Morioka et al and Furuya et al examined this in human jawbones, and reported the same results [20][21][22] . Following tooth extraction, the external form of the jawbone changes in response to multiple local and functional factors 25) .…”

“…It is a bone quality evaluation method that can be used to quantitatively evaluate BAp crystallite alignment in localized regions. Nakano et al used this method to examine the ulnae, calvaria and mandibles of experimental animals and suggested site speci city of BAp crystallite alignment 19,20) . Morioka et al and Furuya et al also used this method for detailed analysis of BAp crystallite alignment in human jawbone and reported that dentate mandibles exhibit a double structure on a nanoscale 21,22) .…”