Flexural behaviour of post-cured composites at oral-simulating temperatures

Post-curing treatments have been known to improve the mechanical stability of visible light-cured composites. After individual post-curing treatment, the flexural strength (FS) of four commercial direct/indirect placement com posite materials which differ greatly in composition [oligocarbonate dimeth acrylate (OCDMA)-based Conquest C & B (CQT), Bisphenol-A glycidyl dimethacr ylate (BisGMA)based Charisma, urethane dimethacrylate (UDMA)based Concept ( CCT), and BisGMA/UDMA-based Dentacolor] was evaluated under water in the te mperature range of 12-50 degreesC. A control series was tested in air at ro om temperature (25 +/-1 degreesC). Data were analysed using ANOVA and Dunca n's test. Flexural strengths overall decreased (20-40%, P < 0.01) with incr easing temperatures except with Conquest C & B. Surprisingly, higher FS val ues were found in wet conditions than in dry conditions at 25 <degrees>C. U DMA-based materials much more easily undergo softening in water and by temp erature change than do Bis-GMA- or OCDMA-based materials. Post-cured compos ites can be significantly affected by exposure to oral environments. Differ ent composition determines the degree of influence.