Composite Depth of Cure Using Four Polymerization Techniques

UNLABELLED The light-curing technique is relevant to reduce the degree of polymerization shrinkage, improving clinical and esthetic success of composite resin restorations. OBJECTIVE To evaluate in vitro the effect of four light-curing techniques on depth of cure of a composite resin. MATERIAL AND METHODS Ten specimens of a composite resin were made in cylindrical cavities prepared in PVC plates (3.0 X 7.0 mm) for each light-curing technique. Four photoactivation methods were investigated: stepped, ramped, pulse-delay and traditional. Specimens were longitudinally sectioned and polished for microhardness measurements (kg/mm(2)), which were made at 0.1, 1.0, 2.0 and 4.0 mm from the irradiated surface. Data were subjected to ANOVA and Tukey's test. RESULTS The effect of factors studied (curing method and distance from the surface) and the interaction of these factors was statistically significant (p<0.05). The traditional method of cure provided higher microhardness values (69.6 +/- 2.5) than the stepped (63.5 +/- 3.1) and pulsed (63.9 +/- 3.2) methods at all depths evaluated, but it did not differ from the ramped method (66.7+/- 4.4) at 0.1 and 1.0 mm of depth. CONCLUSION All techniques employed provided satisfactory cure of the composite resin up to the depth of 2.0 mm from the irradiated surface.