The effect of "soft-start polymerization" on surface hardness of two packable composites.

It has been reported that light-initiated prepolymerization at low intensity followed by a post-light-cure at full intensity (soft-start polymerization) may lead to light-cured composite fillings with improved marginal integrity. The aim of this study was to examine the influence of softstart polymerization with different protocols on Vickers hardness of different packable composites. Vickers hardness of packable composites ALERT, and Definite were measured with a Vickers indenter and were evaluated. The results suggested that independent of the applied curing mode and curing tip, Alert showed significantly higher Vickers hardness than did Definite (p<0.05). There was no significant influence of curing mode or light guide on Vickers hardness of the samples tested. In conclusion, we found that soft-start polymerization does not have a significant influence on the degree of conversion, when compared with the conventional method. In addition, different light tips showed no significant improvement on surface hardness.