Color stability, opacity and degree of conversion of pre-heated composites

ObjectivesTo assess color stability and opacity associated with the degree of conversion of a pre-heated nanohybrid composite (Tetric N-Ceram, Ivoclar/Vivadent, Schaan, Liechtenstein).MethodsTwenty-seven specimens were prepared (n = 9) using a Teflon matrix following storage of compules containing the composite at temperatures of 8 °C, 25 °C or 60 °C. After photoactivation and polishing, baseline readings of six specimens were taken regarding their color and opacity (Spectrophotometer PCB 6807, Byk Gardner, Geretsried, Germany). Then, the specimens were submitted to artificial ageing for 384 h (C-UV, Adexim Comexim, São Paulo, SP, Brazil), after which the final readings were taken. Three specimens for each temperature were submitted to analysis of degree of conversion (Nicolet 380, Thermo Scientific, Waltham, MA, USA). The results were analysed by 1-way ANOVA/Tukey (p < 0.05).ResultsThere was no significant difference in color stability and opacity variation amongst the temperatures evaluated. The composite pre-heated at 60 °C had a higher degree of conversion (65.13%), with statistically significant difference compared to the other temperatures (p < 0.05).ConclusionsComposite pre-heating does not promote changes in the optical properties, despite the increase in the degree of conversion.