Abstract
A digital image correlation method was applied to study the polymerization shrinkage of a light cure resin composite in cavities of bovine teeth. A cylindrical cavity prepared using a bonding agent was employed to measure the shrinkage behavior on the top free surface of the cavity. A semi-cylindrical cavity was also used to simulate the cross section of the cylindrical cavity. The resin filled in the cavity was irradiated using a visible-light curing unit and photographed with a CCD camera as a function of time. The cavities prepared without the bonding agent were employed to study the bonding strength at the interface between the resin and tooth substrate, and the following results were obtained. The shrinkage behavior was largely different in the cavities prepared with and without the bonding agent. With the bonding agent, the displacement distribution was continuous at the interface, and its absolute value exhibited the maximum in the resin close to the interface and the minimum near the center of the cavity. Without the bonding agent, there existed the interface which exhibited the discontinuous distribution, and the discontinuity tended to initiate and grow locally at the interface.
