【摘要】 目的研究牙科陶瓷的非线性膨胀特征。方法制作6种牙科陶瓷的长方体试件,用热膨胀仪测定470～25℃区间的热膨胀曲线,对该温度范围数据进行直线回归分析(ΔL/L=C+αT)和二次回归分析(ΔL/L=C+α1T+α2T2),测得每种材料的一次回归系数α和二次回归系数α1、α2。结果回归分析显示,所有陶瓷材料热膨胀曲线均表现出非线性特征,二次回归系数α1衡量曲线的倾斜程度,α2衡量曲线的弯曲程度。结论二次函数拟合陶瓷的热膨胀曲线可行且准确,该方法更加精确地描述了陶瓷的膨胀特征。更多还原

【Abstract】 Objective In this study thermal contraction curves of six dental ceramics were measured and the polynomial function L/L= C+α1T+α2T2 was suggested to describe the thermal contraction behavior of dental porcelain.Methods The thermal contraction curves of two ceramic cores and four veneering porcelains were measured on cooling from 470 ℃ to 25 ℃ by means of a vertical differential pushrod thermal dilatometer.Contraction data as a function of temperature (470-25 )℃ was fit by regression analyses to both linear fitting and non-linear relation by a quadratic curve fitting procedures.Results In this study,all the ceramics showed non linear dimensional change during cooling.For the quadratic curve fitting procedure the two coefficients α1 and α2 are given to describe the shape of the curve.The first-order coefficient (α1) represents the steepness of the curve and second-order coefficient (α2) represents the bending depth of the curve.Conclusion Quadratic fitting procedure is a promising method to describe thermal dimensional behavior of dental ceramics because it can better represent original data.更多还原