Resumo

RODRIGUES, Rodrigo Araújo et al. Analysis of the Knoop microhardness of four types of composite resin by HVS-1000 microhardness tester. Odontol. Clín.-Cient. (Online) [online]. 2010, vol.9, n.1, pp. 55-58. ISSN 1677-3888.

The objective is to evaluate the microhardness of four types of composite resins from the same manufacturer. Six specimens were divided into 4 groups, where in each one of 3M ESPE resin (FiltekTMP60, FiltekTMZ350, FiltekTMZ250 and FiltekTMZ100) was used. To standardize the samples, cylinders of resin were used with 2 mm in height and 5 mm in diameter as matrix. Curing was applied for the time recommended by the manufacturer: 20 seconds in resins P60, Z350 and Z250 and, 40 seconds in Z100. To ensure a polished surface using a strip of polyester pressed against the matrix during polymerization. Distance to curing was standardized by a layer placed on thespecimens, ensuring the same distance from all. The bodies were sent for analysis of the Knoop microhardnesstester. Each body was examined in 3 different areas on its surface, in time of 5 secondsof application of load (0.49 N). The arithmetic mean for each group was calculate and arranged inthe data table for analysis. The P60 showed higher hardness resin surface while the Z350 is shownwith lower hardness. So we can conclude that the microhardness of the resins is directly associatedwith the disposal of particulates and opacity, interfering with the ability of_curing.

Palavras-chave : composite resins; hardness tests; operative dentistry.