PMID: 11933908Apr 6, 2002Paper

Effect of the photo-activation method on polymerization shrinkage of restorative composites

Operative Dentistry
Andresa Carla ObiciLourenço Correr Sobrinho

Abstract

This study measured the gap that resulted from polymerization shrinkage of seven restorative resin composites after curing by three different methods. Contraction behavior, according to the specimen region, was also characterized. The materials used for this study were Alert (Jeneric/Pentron, Wallingford, CT 06492, USA), Surefil (Dentsply Caulk, Milford, DE 19963, USA), P60 (3M Dental Products, St Paul, MN 55144, USA), Z250 (3M), Z100 (3M), Definite (Degussa-Hüls, Hanau, Germany) and Flow-it (Jeneric/Pentron). The composite was placed in a circular brass mold 7 mm in diameter and 2 mm in height. Photo-activation was performed by a) continuous light (500 mW/cm2) for 40 seconds; b) stepped light with low intensity (150 mW/cm2) for 10 seconds and high intensity (500 mW/cm2) for 30 seconds and c) intermittent light (450 mW/cm2) for 60 seconds. The top and bottom surfaces were then polished and after 24 +/- 1 hours, the contraction gap was measured by SEM at variable pressure (LEO 435 VP, Cambridge, England). Results were analyzed by ANOVA and the means compared by Tukey's test (5%). The results demonstrated 1) the continuous light method presented the greatest gap values (15.88 microm), while the other methods demonstrated lower po...Continue Reading

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