Abstract

LORETTO, Sandro Cordeiro et al. In vitro evaluation of polymerization shrinkage gap of different universal composite resins. RSBO (Online) [online]. 2010, vol.7, n.4, pp. 430-438. ISSN 1984-5685.

INTRODUCTION: Composite resins are the major direct restorative material used in daily dental practice nowadays. However, some aspects of this material need further investigation, such as polymerization shrinkage. OBJECTIVE: To investigate the polymerization shrinkage gap of different universal composite resins. MATERIAL AND METHODS: Experimental groups comprised eight commercially available composite resins (n=5), as follows: G1 - TPH Spectrum (Dentsply); G2 - Esthet-X (Dentsply); G3 - Opallis (FGM); G4 - Filtek Z250 (3M Espe); G5 - Natural Look (DFL); G6 - Master Fill (Biodinamica); G7 - Filtek Z350 (3M Espe); G8 - Filtek Supreme XT (3M Espe). Each composite was inserted into a circular brass mold (7-mm diameter; 2-mm height), covered with a polyester strip, and then pressed by two glass plates. Following, the specimens were light-cured through only one of the surfaces by using a conventional halogen light device (Optilight Plus, Gnatus), with light intensity of 500 ± 10mW/cm², according to the manufacturer's instructions. Then, the samples were polished, and, after 24 hours, the polymerization shrinkage gaps were measured by scanning electronic microscopy. The measurements were performed at four points (3, 6, 9, and 12 o'clock). Data were submitted to analysis of variance and Student-Newman-Keuls test with 5% of confidence level. RESULTS: Filtek Z350 (3M Espe) showed the highest mean of polymerization shrinkage gap, while Natural Look (DFL) presented the lowest mean. CONCLUSION: Differences in the organic matrix, as well as in the filler content, significantly affected the polymerization shrinkage gap of universal composite resins.

Keywords : dental materials; composite resins; light.