Heat Application Dependence of the Vickers Microhardness Behavior of Dental Filling Materials

Abstract

The aim of this study is to compare microhardness 24 hours after the initial setting of a glass ionomer material and a resin modified glass ionomer filling material with and without heat application. Twenty cavities were prepared to a depth of 2 mm and diameter of 7 mm on acrylic resin (Meliodent; UK) discs. The groups were as follows; Group1 - Equia without heat application (GC, Japan); Group 2- Equia (GC, Japan); with heat application; Group 3 - Riva LC without heat application (SDI, Australia); Group 4 - Riva LC with heat application (SDI, Australia). A light curing unit was used (GCP CarboLED CL-01; GCP Dental, Netherland) for heat application. Specimens’ surfaces were prepared by polishing  and microhardness tests were done 24 hours after the initial setting by using Vickers microhardness tester with 9.8 N (1000 gr 15 s dwell time). For Vickers Hardness test one-way analysis of variance (ANOVA) was used to statistically analyze data at the p < 0:05 level of significance. Microhardness values were respectively obtained as Group 1=519.525, Group 2=548.518, Group 3=495.296 and Group 4=465.666 MPa. The lowest hardness values were recorded resin modified glass ionomer (Riva LC) with heat and light application. No statistically significant difference (p<0.05) was found in the Vickers hardness when heat and light application time were compared. Considering the measured mechanical properties, it is found that heat application increases the microhardness degree of glass ionomer filling material but heat application decreases the microhardness degree of resin modified glass ionomer filling material for the samples which were tested 24 hours after initial setting