Rheological studies of photopolymerized dental composites.

An oscillating rheometer was constructed to study the polymerization of light-cured dental composites. The instrument is based on the forced harmonic oscillator, where the polymerization of the sample leads to a reduction of amplitude of oscillations. The polymerization time as determined for different materials seemed to be influenced by the filler particle size. The results obtained for the viscosity and shear modulus for a class of samples agreed with values published using other instruments and methods.

Optical transmittance of reflecting wedges.

This study quantified the light intensity transmitted by the reflecting wedges perpendicularly to the growth axis. The results demonstrated that the cervical wedges did reflect the light of 180 degrees and original light intensity diminished by 83.9%. The maximal light intensity transmitted to the resin by the wedge was less than 8% of that receiving direct exposure to the curing wand. Differential measurements made on points closely spaced along the sides of the wedge indicated a maximal intensity at approximately 2 mm from the base of the wedge.