Papers by Keyword: Alumina Glass Composite

Abstract: Objective: to describe and demonstrate an oral mucosa irritation and a skin sensitivity test for evaluation of the biological safety of a colored alumina/glass composite (AGC). Methods: colored alumina/glass composite and control materials were sutured to mucine bilateral cheek pouch mucosa, in a position for gross observation and for histological and cytological examination; skin irritation activity of the composite was tested by intradermal injection of a guinea pig test solution, by inducing, enhancing, and stimulating the allergic response observed after local tissue exposure. Results: colored AGC in mouse cheek pouch mucosa stimulated the same reaction as the control, with no significant inflammatory reaction or infiltration of inflammatory cells. Guinea pigs showed no obvious erythema or edema from the irritation test, such that the assessment of colored AGC skin allergy response in mice was 0%. Conclusion: colored AGC was benign towards mouse oral mucosa and elicited no allergic skin inflammation response, indicating that in these aspects this material had good biological safety.

Abstract: Objective: to evaluate the biological safety of a colored alumina/glass composite in terms of cytotoxicity and hemolytic ability. Methods: the cytotoxicity of an alumina/glass composite was evaluated with molecular filtration method. Cytotoxicity by spectrophotometric responses of test material and responses of a fresh rabbit red blood anticoagulant solution was determined by spectrophotometer. Results: cell-coated filter paper in contact with the test material showed the appearance of intracellular blue dye as the same staining density as in control samples, leading to a toxicity rating of 0. Colored alumina/glass composite assayed at <5% hemolysis. Conclusion: colored alumina/glass composite materials showed low cytotoxicity and non-acute hemolytic rates, representing overall good biological safety under these conditions.

Abstract: Abstract. The improvement of subcritical crack growth (SCG) resistance for alumina glass dental composites was explored in this study. The addition of nitrogen to the glass phases in the composite was found to increase the SCG resistance, where the SCG exponent n increases from 22 for the oxide glass composites to 30 for the composites containing 0.5 mol% nitrogen in the glass phases. The improvement was tentatively attributed to the nitrogen addition, which makes the glass network stronger through forming the non-flexible Si-N bonds and thus inhibits the hydrolysis reactions under the SCG conditions. Analyses demonstrated that the increase of the n value from 22 to 30 offers the potential to greatly extend the lifetime and improve the long-term reliability for the alumina glass dental composites.

Abstract: Alumina/glass composites were successfully fabricated by melt-infiltration of glass into porous alumina pellets. Alumina powder was first pressed uniaxially at 100MPa to form disc-shaped pellets, then, heated up to 1200°C for 2 h to form porous pellets with moderate strength for subsequent infiltration. A mixture of calcium aluminosilicate and magnesium borosilicate glass powders were melt-infiltrated into porous alumina at 1200°C ~1250°C by capillary pressure to form composites. The infiltration depths varied with the square root of infiltration time. And the activation energy of the infiltration process was estimated to be 621 KJ/mole. After complete infiltration, the composite had bulk density approaching 3.3 g/cm3 (~ 96% of theoretical density) and open porosity reaching zero, with slight expansion of 0.5% in diameter. Its flexural strength was 150MPa and its Vickers microhardness was about 1000 Kg/mm2.