The study on fabrication of dental restoration using PMMA-ZrO2 composites via CAD/CAM / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To obtain dental restorations by machining PMMA-ZrO2 organic-inorganic composites with the dental CAD/CAM system.</p><p><b>METHODS</b>Partially sintered Zirconia compacts (PSZC) were prepared via isostatic pressing and partially sintering, with Zirconia nanopowder as raw materials. PMMA-Zirconia organic-inorganic composites were prepared by vacuum infiltrating the prepolymerized MMA into the PSZC, followed by in-situ polymerization. The mechanical properties and machinability of composites were studied. The composites were machined on the dental CAD/CAM system to obtain dental restoration.</p><p><b>RESULTS</b>At 71.44% TD of PSZC, the composite had a 3-point bending strength of (202.56 +/- 3.09) MPa, fracture toughness of (4.30 +/- 0.16) MPa.m(1/2), elasticity modulus of (58.71 +/- 1.98) GPa, and Vickers hardness of (3.82 +/- 0.34) GPa, respectively. A premolar crown was fabricated by CAD/CAM system in 16 mins, and was verisimilitude, without any cracks.</p><p><b>CONCLUSIONS</b>The composite at 71.44% TD of PSZC has good mechanical properties and dental restorations can be manufactured by PMMA-Zirconia composites via dental CAD/CAM system.</p>

A study of injectable autogenous tissue-engineered bone / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the utilization of carrier for delivering osteoblasts and creating autogenous bone tissue in ectopic site of animal via injection.</p><p><b>METHODS</b>Bone marrow cells harvested from iliac bone of New Zealand rabbits were induced to differentiate into marrow stromal osteoblasts. The osteoblasts were mixed with 1.5% alginate sodium solution to generate osteoblasts/alginate composites with final cellular density of 4 x 10(9)/L. Calcium chloride was used as cross-linking agent to gel aqueous alginate solution. The marrow stromal osteoblasts/alginate composites were injected into the dorsal subcutaneous tissue of rabbits with autogenous cells transplantation. The samples were examined with X-ray and histological analysis.</p><p><b>RESULTS</b>Four, eight and twelve weeks after injection, the hard knobbles were easily palpated under the dorsal skin of animals. On X-ray photograph the samples showed calcified image with more density than surrounding soft tissue, new bone formation was observed in the osteoblasts/alginate composites in histological analysis. The osteogenesis was in association with regenerated hematopoietic bone marrow.</p><p><b>CONCLUSIONS</b>These results demonstrate that new bone tissue could be created through the injection of alginate sodium treated with autogenous marrow stromal osteoblasts.</p>