Thermal diffusivity of glass-ionomer cements.
Thermal diffusivity, a property related to the thermal insulative efficiency of a material, was measured in nine glass-ionomer cements and compared with results from a silicate and a polycarboxylate cement. Each cement was mixed at various powder-liquid ratios (P/L) and moulded into a rectangular prism of approximate dimensions 2 cm cube with a thermocouple embedded in it. The prism was immersed in a constant-temperature bath at 1 degree C, and the fall in temperature was observed over a period of three min. Except for the initial and later stages, the plot of the logarithmic difference between external and internal temperatures of each block of cement against time showed a straight line in accord with theoretical prediction. From the slope, the thermal diffusivity of the material was calculated. The values for the silicate, polycarboxylate, and glass-ionomer-metal (cermet) showed a marked rise with increasing P/L, whereas at higher P/L, glass ionomer cements showed gradual change, with values being only slightly higher than the thermal diffusivity of dentin. Glass-ionomer cements are good thermal insulators over a wide range of P/L, and close agreement between experimental and theoretical data shows that glass-ionomer cements are homogenous isotropic materials.
D003738:Dental Cements; D005899:Glass Ionomer Cements; D006358:Hot Temperature; D008422:Materials Testing; D011076:Polycarboxylate Cement; D012823:Silicate Cement; D013814:Thermal Conductivity; D013821:Thermometers
D003738:Dental Cements; D005899:Glass Ionomer Cements; D011076:Polycarboxylate Cement; D012823:Silicate Cement