Influence of the curing method on the post-polymerization shrinkage stress of a composite resin

Made available in DSpace on 2019-09-12T16:56:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2008The aim of this study was to evaluate the effect of different curing methods on the stress generated by the polymerization shrinkage of a restorative composite in two moments: immediately after light exposure and after 5 min. Photoactivation was performed using two different light sources: (1) xenon plasma are (PAC) light (1,500 mW/cm(2) - 3s) and (2) a quartz- tungsten-halogen (QTH) light with three light-curing regimens: continuous exposure (40 s at 800 mW/cm(2) - CL); soft-start (10 s at 150 mW/cm(2) and 30 s at 800 mW/cm(2) - SS) and intermittent light [cycles of 4 s (2 s with light on at 600 mW/cm(2) and 2 s of light off), for 80s - IL]. The composite resin was applied between two 5-mm diameter metallic rods, mounted in a servohydraulic machine. The maximum stress was recorded immediately after light exposure (FF) and after 5 min (5F). The results were submitted to ANOVA and Tukey's test (5%). For each method, the results obtained in FF and 5F were, respectively: CL (3.58 and 4.46 MPa); SS (2.99 and 4.36 MPa); IL (3.11 and 4.32 MPa) and PAC (0.72 and 3.27 MPa). The stress generated by the polymerization shrinkage during light exposure can be associated with the photoactivation method used. A significant increase in the stress level was observed during the post-curing period up to 5 min, for all evaluated methods.[Cunha, Leonardo Goncalves; Elias Claro Neves, Ana Christina] Universidade de Taubaté (Unitau), Dept Prosthodont[Bruschi Alonso, Roberta Caroline] Univ Estadual Campinas, Dept Restorat Dent, Dent Mat Div, Piracicaba Dent Sch, Piracicaba, SP, Brazil[de Souza, Eduardo Jos Carvalho, Jr.] Univ Fed Bahia, Sch Dent, Salvador, BA, Brazi