Zinc-coated carbonate apatite derived from avian eggshell for potential use as bone substitute. Part I: preparation and properties.

PURPOSE: To develop antibacterial bone substitutes derived from avian eggshell using microwave processing to convert natural calcium carbonate (CaCO3) into zinc-coated carbonate apatite (CHA). METHODS: Zinc-coated carbonate apatite was prepared using domestic microwave and then characterized with scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and energy dispersive x-ray analysis (EDXA). The trial animal study was conducted by filling different bone substitutes into 5-mm-diameter standard defects on the parietal bone of New Zealand rabbits to observe new bone formation for 8 weeks. RESULTS: SEM, XRD, FT-IR, and EDXA confirmed characteristics of zinc-coated CHA derived from avian eggshell using microwave method. Histological analysis demonstrated that the defects filled with carbonate apatite had more calcified bone and less uncalcified bone formation than other groups. CONCLUSIONS: The present research demonstrated the efficient use of microwave in the conversion of natural CaCO3 into CHA with zinc coating. The examined properties showed the potential use of the new material as an antibacterial bone substitute in oral surgery. The trial animal study implied favorable osteoconductive ability of carbonate apatite in new bone formation.

[Jaw bone density assessments of implant sites using spiral CT and Simplant software].

PURPOSE: To assess the bone density of dental implant sites using spiral CT and simplant software, and classify them by Lekholm and Zarb grouping. METHODS: 53 patients' jaw bone were scanned by spiral CT, the scanned images were reconstructed by the Simplant software.The bone density of 136 designed implant sites was measured and the results were recorded using Hounsfield units(HU).The data was analyzed with SPSS11.0 software package for Mann-Whitney U test, and classified by Lekholm and Zarb grouping. RESULTS: The mean bone density in all implant sites was (714.66+/-273.72) HU.The anterior mandible mean bone density was (962.96+/-92.21)HU>anterior maxilla, (786.15+/-188.74) HU>posterior mandible, (785.79+/-290.91) HU>posterior maxilla, (569.67+/-244.34)HU. Bone class IV was least in anterior mandible and most in posterior maxilla(P<0.01), accounting for 26.5% in all implant sites. CONCLUSIONS: Anterior mandible has the highest mean bone density and posterior maxilla has the lowest mean bone density. There are class I and II/III in most of the implant sites. Spiral CT is a useful tool for determining the bone density, which is important for preoperative design and postoperative assessment.