Effect of Temperature on Surface Hardness of Different Acrylic Materials utilized for space maintainer

Abstract

Aim of the study: surface hardness is essential to avoid the indentation or scratch of space maintainer. Efforts have been made to improve the flexible and cold-cured acrylic's strength, by raising the processing temperature, unless the temperature has a chemical impact on the acrylic's qualities. The aim of this study was to study the effect of elevated temperature on the surface hardness of flexible and cold cured acrylic utilized as space maintainer appliance.
 Methods: Sixty specimens were divided into three groups: flexible acrylic ( Lingchen dental) , cold-cured acrylic (vertex) and (Paladur). Each group was subdivided into two subgroups,10 control and10 experimental . The control group for flexible acrylic was injected at 270 °C ,while for the two types of cold -cure, control groups, the specimens were processed at 37°C . The experimental group for flexible acrylic was injected at 290°C and for the two cold -cure types were processed at 70°C. Hardness was tested by Shore A device for flexible acrylic while for cold -cure specimens, shore D device was used. 
 
 Results : results showed no significant increase in the hardness of flexible acrylic the mean value of control group is 66.44±0.47 while for experimental group is 66.50±0.48. For vertex and Paladur cold- cured acrylic the surface hardness was increased significantly with increasing processing temperature. The mean values of vertex and Paladur control groups are around 86.14±0.39 and 88.33±0.39 respectively, while for experimental groups are 88.39±0.40 and 88.70±0.25
 Conclusion : elevated processing temperature increased the surface hardness of both types of cold acrylic however; the hardness of flexible acrylic was not affected by temperature elevation.