The following hypothesis was tested: direct composites additional polymerization improve the surface microhardness of direct composite resin Filtek Z250 (3M ESPE). We prepared 25 specimens (2×4 mm) with a stainless steel mold. Resin specimens were randomly assigned into 5 groups (n=5/per group): G1 – resin Filtek Z250 photoactivated 60 s; G2 – resin Filtek Z250 photoactivated 60 s + autoclave cycle to 134°C for 7 min at a pressure of 2.5 kg/cm3; G3 – resin Filtek Z250 photoactivated 60 s + oven at 125ºC for 7 min; G4 – resin Filtek Z250 photoactivated 60 s + microwave for 3 min to the power of 450W; G5 – indirect resin Resilab photoactivated 60 s + supplementary furnace LUX GDS 4 min. The specimens were fabricated by a metal matrix, filled with resin in two increments and each increment polymerized according to their group. For polymerization of the last layer, we used a glass plate on a polyester strip. Then the specimens were evaluated for surface microhardness Knoop. Additional polymerization media resulted in significant differences among the groups (p<0.05) (One-way ANOVA and Dunnett test, p=0.05). The mean surface hardness Knoop (KHM) were as follows: G1: 51.71±1.73b; G2: 62.37±1.71a; G3: 50.61±1.30b; G4: 52.65±1.125b; G5: 60.15±2.02a; Conclude that the additional polymerization in autoclave increased the surface microhardness Knoop of composite resin evaluated. Hypothesis was partially confirmed.
KEY WORDS: composite resin, microhardness, polymerization.
How to cite this article
CARVALHO, R. F.; FARIA, C. R.; CRUZ, F. L. G.; FARIA, J. C.; B. & LEITE, F. P. P. Consequences of the additional polymerization on knoop microhardness of direct composite resin. Int. J. Odontostomat., 7(1):93-98, 2013.