Laser interferometric method for measuring linear polymerization shrinkage in light cured dental restoratives (original) (raw)

A novel laser interferometric method for monitoring linear polymerization shrinkage in dental restoratives is demonstrated. The experimental apparatus consists of a low power Helium-Neon laser, a home-built Michelson interferometer, amplified photodiode detectors, and a computer data acquisition system. The feasibility of using interferometry to measure linear shrinkage was evaluated by measuring the percent linear contraction in five commercially available light cured restorative systems. Five-min interferometric curing profiles were collected for each restorative using a 400 mW/cm2 curing light irradiance. The 'interferograms' were converted into percent linear contraction profiles that revealed the relative kinetics of material shrinkage. The overall percent linear contraction after 5 min compares favorably with literature data for the five commercial restoratives studied here. Interferometry offers several advantages over conventional methods of measuring polymerization ...