Polymerization shrinkage distribution of during dental restoration observed by digital image correlation method

Polymerization shrinkage distribution of composite resins during dental restoration was measured using digital image correlation method. Camera images were monitored during and after the light irradiation. Radial shrinkage strain was to be averagely 0.27% for AP-X and 0.12% for P90 over the whole resin area. Calculated strain results by finite element analysis were lower by 8% ~ 26% than experimental values obtained by digital image correlation. The shrinkage strain occurred much larger in the center part of the resin than in the resin/substrate interface region. The average radial strain of resins on the resin/substrate interface rapidly shrank within 4 minutes, and then converged to a constant value with an increase of time.