Changes in Bone Quality Associated with the Mineralization of New Bone Formed Around Implants - Using XPS, Polarized Microscopy, and FTIR imaging

The purpose of this study was to investigate changes in bone quality associated with the mineralization of new bone forming around implants. Eight 18-week-old male New Zealand white rabbits and implants fabricated from Ti-15%Zr-4%Nb-4% Ta alloy were used in the study. Characteristics of new bone formed around implants at 4 and 8 weeks and cortical bone were compared using X-ray photoelectron spectroscopy (XPS) for elemental qualitative and quantitative analysis, polarized microscopy (PM) for histological examination, and Fourier transform infrared Imaging (FTIR Imaging) to characterize molecular distributions in new bone and cortical bone. Results from XPS analysis showed changes in the chemical bonding in new bone over time (4 weeks vs. 8 weeks). PM showed changes in collagen birefringence, orientation and intensity in new bone over time, becoming more similar to those of cortical bone after 8 weeks. FTIR Imaging showed that in new bone close to cortical bone, amounts of PO43- and CO32- ions (representing mineral or inorganic components), and amounts of amide I (representing the organic component) increased over time as mineralization progressed. In new bone more distant from cortical bone, PO43-, CO32-, and amide I distributions also increased over time, but to a lesser extent to that observed near cortical bone. Our findings clearly showed changes in the quality of new bone forming around implants, and these changes were related to mineralization.