Papers by Author: Kihei Kobayashi

Abstract: We have developed a new Ti alloy, Ti-15%Zr-4%Nb-4%Ta alloy (Ti-15-4-4) that showed higher biological safety and mechanical properties than the currently used Ti-6%Al-4%V alloy. The purpose of this study is to determine the biological performance of the new alloy. Ti-15-4-4 implants (machined or blasted) were placed in surgically created defects in rabbit femurs. The rabbits were sacrificed after 4, 8, 16, 24 and 48 weeks. Bone mineral density (BMD) and area of newly formed bone around the implants were measured using micro-CT. Results showed that the Ti-15-4-4 alloy is biocompatible and forms new bone around the Ti-15-4-4 implant, regardless of the surface treatment. The BMD and area of newly formed bone around the blasted implant surfaces were significantly greater than those around the machined surfaces. These results indicate that the new Ti-15-4-4 alloy has a potential for use as implants and has the advantage of improved mechanical properties described in earlier studies.

Abstract: The purpose of this study was to evaluate synthetic calcium phosphates and animal bones using Raman spectroscopy and explore the possibility of its application in characterizing newly formed bone around implants. Synthetic calcium phosphates (monobasic calcium phosphate, dibasic calcium phosphate, tribasic calcium phosphate, fiber apatite, hydroxyapatite and carbonate hydroxyapatite) and animal bones (from pig, cow, rabbit with and without implants) were analyzed in this study. Slight differences in the Raman bands among the 7 types of synthetic calcium phosphate were observed. Furthermore, a 3 cm-1 difference was noted in the bands of the main PO4 3- in rabbit’s bone formed around the implant, compared to the existing bone, suggesting a difference in the molecular structure between the existing and newly formed bones.

Abstract: The purpose of this study is to determine the potential of the LEBRA-PXR imaging in investigating the details of newly formed bone around the dental implants. Transmission image observation of the undecalcified specimen at the wavelength of 1.771 Å showed clearly the formation of immaturely calcified new bone around the dental implants which could not be observed in the usual CMR nor conventional X-ray imaging apparatus.

Abstract: Our studies previously demonstrated that new bone formed around implants can be classified into 3 or 4 types based on tissue structure and composition. Results of the present study, using polarized light microscopy, and microscopic Fourier transform infrared spectroscopic imaging (micro-FT-IR) and micro-XRD to examine different areas in the peri-implant new bone, suggest differences in crystallinity (crystal size) between pre-existing bone and peri-implant new bone.