A review of the curing mechanics of composites and their significance in dental applications.

Much of the technique sensitivity associated with polymer matrix composites is a direct result of their curing shrinkage. Challenges with marginal integrity, adaptation of proximal contact, and residual stress are related to this intrinsic property. There are many test methods described in the literature that measure various aspects of polymerization contraction. Some measure total contraction, which is the sum of pre- and postgelation shrinkage, whereas others are sensitive only to postgelation deformation, which occurs after the onset of measurable stiffness. Development of methods to compensate for curing shrinkage is best described on the basis of an understanding of the polymerization mechanics. The distinction between total and postgelation contraction, and recognition of limitations of test methods are important considerations when interpreting literature data before selecting a restorative material.