Influence of photoactivation methods on resin-composite wear resistance

In an attempt to reduce the stresses generated during polymerization shrinkage of composite-resins or minimize its effects, different light-curing techniques have been proposed as alternatives to the conventional technique, and suggest the use of low power density at the initial moments of the polymerization reaction. Objective: this study was conducted to investigate the in vitro abrasive wear of a composite-resin subjected at four different photoactivation methods, as well as in the susceptibility of the final polymer structure formed, in function of the variation of the way of storage, watery or alcoholic. Methods: device VIP (BISCO), that it makes possible independent commands of power density and time was selected. Four different photoactivation methods had been investigated: Conventional (C: 600mW/cm2 X 40s), Pulse-delay (PD: 200mW/cm2 X 3s 3 min wait 600mW/cm2 X 37s), Pulse-delay plus (PDP: 600mW/cm2 X 3s 3 min wait 600mW/cm2 X 37s) and Soft-start (SS: 200mW/cm2 X 10s 600mW/cm2 X 30s). After the photoactivation, the specimens had been stored in two distinct ways, distilled water and solution of ethanol 75%, for 24 hours, and submitted to the test of simulated toothbrushing. The data had been analyzed by statistical tests two-way ANOVA and Tukey. Results: ranking the abrasive wear values for both distilled water and ethanol solution were as follows: PDP>C>SS>PD. Conclusions: photoactivation methods which use low power density had not compromised the abrasive resistance of the composite resin tested, when comparable to that with high intensity light.