Effects of ovariectomy on rat mandibular cortical bone: a study using Raman spectroscopy and multivariate analysis

To investigate the effects of ovariectomy (OVX) on rat mandibular bone, the physicochemical compositions of mandibular cortical bone of ovariectomy and sham operated rats 2, 4, and 8 months after surgery were compared using Raman spectroscopy. With principal component analysis and linear discriminant analysis based on the Raman spectra, the mandibular cortical bone of the OVX group was clearly distinguished from that of the sham-operated group 8 months after surgery with no overlap. Specifically, significant reductions in the mineral-to-matrix ratio and full width at half-maximum as well as a significant increase in the carbonate-to-phosphate ratio were observed in the mandibular cortical bone of the OVX group. Results support the hypothesis that Raman spectroscopy is sensitive enough to distinguish between OVX and sham-operated mandibles with multivariate analysis by detecting the chemical composition of the mandibular cortical bone. The parameters mineral-to-matrix ratio, carbonate-to-phosphate ratio, and full width at half-maximum can appropriately characterize changes in the chemical composition of the mandibular cortical bone after OVX.