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.

Nonwoven silk fibroin net/nano-hydroxyapatite scaffold: preparation and characterization.

The purpose of this study was to prepare and characterize a three-dimensional scaffold consisting of porous nonwoven silk fibroin net/nano-apatite composite. The silk fibroin net was mineralized with apatite by alternative soaking in calcium and phosphate solutions. The scaffold exhibited a porous microstructure with open porosity (70-78%), with an average pore size of about 163 +/- 40.0 microm. The swelling ratio and water uptake were 4.55% and 81.93%, respectively, indicating excellent hydrophilicity. The nano-sized hydroxyapatite crystals were needle like, with a length of approximately 100-300 nm and a diameter of approximately 20-60 nm. The results of in vitro cell culture study using rat osteoblast cells demonstrated that the nonwoven silk fibroin net/nano-apatite composite showed excellent cytocompatibility for the growth of osteoblasts and had the capability to improve the viability of osteoblasts.

Antibacterial effect of zinc phosphate mineralized guided bone regeneration membranes.

PURPOSE: Current commercial guided bone regeneration membranes are susceptible to bacterial colonization, leading to premature membrane degradation. The purpose of this research is to modify current resorbable guided bone regeneration membranes with antibacterial property by mineralizing with zinc phosphate. MATERIALS: Resolut Adapt LT (Gore-Tex; W.L. Gore & Associates, Inc., Flagstaff, AZ), composed of copolymer PGA/TMC, and BioMend Extend (Zimmer Dental, Carlsbad, CA), composed of bovine type 1 collagen, were used. The membranes were mineralized with zinc phosphate. The mineralized membranes were characterized using scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction, Fourier transform infrared spectroscopy, inductive coupled plasma, and thermogravimetry. Antibacterial property of zinc phosphate mineralized and nonmineralized membranes were determined using Actinobacillus actinomycetemcomitans standard strain ATCC 29522. RESULTS: Scanning electron microscopy, energy dispersive system, and Fourier transform infrared identified zinc phosphate in the zinc phosphate mineralized membranes. Zinc phosphate mineralized membranes showed significant reduction in bacterial colony, forming units compared to nonmineralized membranes. CONCLUSION: Results of this study suggest that the use of zinc phosphate mineralized membranes can inhibit oral bacterial colonization and prevent inflammation due to membrane exposure. This antibacterial property may help achieve the optimal goal of guided bone regeneration.