Electric fluctuations in the developing world are common and may affect dental composite curing. We determined the effect of variable voltage and increasing thickness of different shades of composite on its depth-of-cure.

ISO scrapping method was used on 14 commonly used shades of Esthet-X HD composites. Student's t-test and ANOVA were applied to compare the mean depth-of-cure and a linear regression model was developed using variables voltage (180 V and 220 V), material thickness (2, 4 and 6 mm) and shades (n = 14).

The mean curing depth of samples was significantly reduced at 180 volts compared to 220 volts (p-value <0.002). At thickness of 2 mm, all samples were fully cured but when it was raised to 4 mm, the depth-of-cure reduced to 1.86 mm ± 0.06; while at 6 mm thickness, it reached to 1.96 mm ± 0.06 (p-value < 0.001).

Around 82% variation in the depth-of-cure is explained by voltage, thickness and shade of composite material (p-value <0.001).

Electric fluctuations are prevalent in the developing world and thus poor voltage flow is responsible for dental composite's inadequate polymerization.

Khan FR, Hasan M, Azam SI. The Effect of Different Shades, Voltages and Increment Thickness on the Polymerization Depth of a Microhybrid Composite. Int J Prosthodont Restor Dent 2012;2(2):52-56.