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Effect of light activation method on flexural properties of dental composites
Jack L Ferracane1, Lucas L Ferracane, Lawrence Musanje
1Department of Biomaterials and Biomechanics, Oregon Health & Science University, 611 S.W. Campus Drive, Portland, Oregon 97239, USA. ferracan@ohsu.edu
Purpose:
To determine if irradiating composites in a laboratory tungsten-halogen light-curing unit produced equal flexural properties to stepwise hand-curing with a tungsten-halogen lamp.
Methods:
Bars (n = 10) of nine commercial composites were formed by light-curing in square glass tubes (2 x 2 x 25 mm). Flexure strength (FS, MPa) and flexure modulus (FM, GPa) were tested in three-point bending after aging specimens in water at 37 degrees C for 1 day. Two methods were used to irradiate the composites: a) Triad II (Dentsply) using 40-second exposures from top and bottom; and b) Optilux 400 (Demetron; 600 mW/cm2) using 3 x 40 seconds overlapping exposures from the top only. Filler wt% was determined by thermal gravimetric analysis. The degree of conversion (DC) of each composite cured with the two techniques was evaluated by micro-FTIR. T-tests were performed for FS and FM to compare Triad II vs Optilux for each composite (alpha < 0.05).
Results:
There was a trend for Optilux to produce greater FS (significant for A110, Herculite and P60) and FM (significant for all but Clearfil, Esthet-X and Z250), but differences averaged less than 10%. There was no difference in DC between the irradiation modes for any composite.
