An integrated systems approach to the placement of posterior composite resins.

merization of dental composite materials during lightcuring is a leading cause of adhesive restoration failure, resulting in postoperative sensitivity, marginal staining, and recurrent caries.1 This polymerization contraction shrinkage creates stresses as high as 13 MPa between the composite material and tooth interface2 (1 MPa = 145 psi). This stress can exceed the tensile strength of the enamel and result in stress cracking and enamel fractures along the interface.2 When a composite resin is cured, the surrounding tooth structure deforms due to polymerization shrinkage.3 This deflection can range from 4 to 6 μm, depending on the filling technique used.4 It has been well established that the higher the intensity of the light source, the greater the contraction force at the composite-tooth interface, and use of intermittent or lower light intensities results in improved marginal integrity.5