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 soft-start 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.