Study of microhardness in depht of composite resin polymerized with argon laser and halogen light

ABSTRACT

The purpose of this study was to evaluate the polymerization of two composite resin (a microhybrid Z250 and a microfill A-110) with the application of halogen light and the argon laser. The Vickers microhardness were analysed in vitro at the depth of the first 3 milimeters and polymerized in 3 incremments of 1 mm each or in only one incremment of 3 mm. 180 specimens were used in a black matrix. The statistical result of the microhardness test showed that argon laser applied during 30 seconds to the microhybrid resin was similar to the halogen light applied to the same resin during 40 seconds, followed by laser and halogen light for 20 seconds, and finally the argon laser during 20 seconds. The microhardness values were higher for halogen light applied during 40 seconds to the microfill resin, followed in decreasing order by the argon laser applied for 30, 20 and 10 seconds. There was also a decrease in hardness with increasing depth for both resins and using the incremental technique the values were higher than using only one increment. Analysing the quality of polymerization it was found that microhybrid resin showed a satisfactory level of polymerization in the first and second milimeter with halogen light applied for 20 or 40 seconds and only in the first milimeter with the laser applied for 30 seconds. The microfill resin only showed a satisfactory level of polymerization with the halogen light applied for 40 seconds in the first milimeter.