Effect of Temperature, Time and some Additives on Denture Base Material

The aims of this study were to evaluate the effect of change in time ,temperature (increase or decrease) and some additives(Nigella sativa and Thyme oil) on the degree of conversion, residual monomer release, transverse strength, indentation hardness, volumetric and color changes of the vertex heat cured acrylic resin.The results of the present study were analyzed statistically by (Descriptive statistics, ANOVA and Duncan¿s multiple range test). The results of this study showed that both changes in time and temperature showed significant changes in the degree of conversion, residual monomer, transverse strength, volumetric and color changes in the three curing cycles without additive. The used additives (Nigella sativa and Thyme oil) increased the conversion, increased the residual monomer release, showed a slight increase in volumetric change for the short cycle,(0.35-1.05) for the rapid simplified and for the regular curing cycles in comparison with their standard curing cycles without additives and color change, ¿E =3.376 (which is an acceptable change in vitro) for the Thyme oil additive to the regular heat curing cycle in comparison to the standard short cycle.