Influência do acréscimo de porções pré-polimerizadas no grau de polimerização de compósitos odontológicos [Title in english no available]

Abstract

Some limitations of light-cure composites that are used in posterior teeth are: the plymerization shrinkage, postoperative sensibility and por marginal adaptation. Intending to dicrease or avoid those limitations, Teruya et al¹² recommended the insertions of prepolymerized portions during the elaboration of restorations. To determine if there is any interference of light passage during photopolymerization of composites, Knoop hardness measurements (N. U. Reserch microscope, 20g load) were made at the surface and botton of 20 samples divided in 4 groups: |) control; Il) with a 1mm megafiller; Ill) with a 2mm megafiller; IV) with a 2,5mm megafiller. Mean Knoop hardnes values obtained on top and botton surface respectively were: : 1)78,27 e 74,23; Il) 75,01 e 74,53; Ill) 76,06 e 72,76; IV)
72,76 e 49,85. The results submitted to ANOVA and Tukey Test with 95% of significance, showed that: A) The addition of prepolymerized portions of composite resin did not change the top surface hardness of the samples; B) The addition of prepolymerized portions of composite resin with 2mm did not change the botton and top surface hardness of the samples; C) the addition of prepolymerized portions with 2,5mm thickness or higher than that decreased, significantly, the bottom hardness of the samples.