Evaluation of the Effect of Microwave Irradiation and Die Hardener Application on Surface Hardness of Type IV Dental Stone

Abstract

Type IV dental stone play an important role during fabrication of indirect dental restoration. It should be accurate in every respect, dimensionally stable over time, hard enough to with stand fabrication process resistant to the inadvertent abrasions caused by fabrication. The aim of present study was to evaluate the effect of microwave irradiation and die hardener application on surface hardness of type IV dental stone. Two commercial brands of type IV dental stone (Spofadental/ Czech, Zhermack/ Italy) were evaluated. 30 samples were prepared from each brand and left to dry for 24hr. After that divided into three groups, control group (10 samples withou t treatment), 10 samples subjected to microwave irradiatio n at 650 watt output power and 2450 MHZ for 10 mint. And 10 samples painted with die hardener. Surface hardness measured with Shore C (Durometer, Digital hardness tester). The die hardener application not affect surface hardness of both brands (P>0.05). However microwave irradiation increase surface hardness of Spofadental Type IV dental stone. But reduce surface hardness of Z hermack Type IV dental stone. After 24hr. of pouring Type IV dental stone (Spofadental / Czech, Zhermack / Italy) die hardener application not affect surface hardness. However surface ha rdness of Spofadental Type IV dental stone may be improved with microwave irradiation. But Zhermack Type IV dental stone s howed reduction in surface hardness after microwave irradiati on.