Avalia？？o de compósitos odontológicos por análise térmica e microscopia eletr？nica de varredura

the aim of this work is to characterize photosensitive dental composites by thermal analysis (tg, dtg and dta) and scanning electron microscopy (sem). among the commercial brands analyzed, four were for indirect use, resilab (wilcos/brazil), epricord (kuraray/japan), signum (heraeus kulzer/germany) and sinfony (3m/usa), while the other two were for direct use, namely 4seasons (ivoclar vivadent/liechtenstein) and esthet x (dentsply/usa). composites for direct use were cured during 20 seconds, while the indirect ones were cured for 180 seconds on different instruments, as indicated by the producers. thermal decomposition of dental composites (cured and uncured) was studied between 30 and 800 °c with a nitrogen flow of 120 ml.min-1. thermogravimetry curves (tg) showed that composites which presented a better thermal stability showed smaller amount of residues at 800 °c. composites micrographs showed different particle sizes. thermal analysis seems to be an interesting tool to evaluate the thermal behavior of dental composites.