Thermal Properties of Dental Materials

Thermal Properties of Dental Materials
THERMAL CONDUCTIVITY
It is the quantity of heat in calories or joules, per second passing through a body 1 cm thick with a cross section of 1 cm2, when the temperature difference is 1°C.

SPECIFIC HEAT
It is the quantity of heat needed to raise the temperature of 1 g of the substance 1°C.

THERMAL DIFFUSIVITY
It describes the rate at which a body with nonuniform temperature approaches equilibrium.

COEFFICIENT OF THERMAL EXPANSION
It is the change in length per unit length of a material for a 1°C change in temperature.

Application:
Restorative materials may change in dimension upto 4.4 times more than enamel for every degree temperature change, when there is cooling contraction and on heating there is expansion of materials, which may eventually lead to marginal leakage adjacent to restoration.
HEAT OF FUSION
It is the heat in calories or joules required to convert 1g of a material from solid to liquid state at the melting temperature.