. 2012 Sep-Oct;20(5):576–580. doi: 10.1590/S1678-77572012000500014

Table 1.

Means (standard deviations) of Vickers hardness number (VHN) of the upper surface of composite resin specimens light cured with light curing units covered with layers of an infection control barrier

LCU	Control	1 Layer	2 Layers	4 Layers	8 Layers
FL2	28.1 (1.2)^Aa	28.0 (1.2)^Aa	27.6 (0.9)^Aa	26.1 (0.7)^Ba	24.6 (1.0)^Ca
O360	20.2 (1.1)^Ab	19.7 (1.3)^ABb	19.2 (0.9)^ABb	19.2 (1.0)^ABb	18.5 (0.9)^Bb

Values having the same capital letters in the rows and the same small letters in the columns are not statistically significant (p>0.05). LCU= light curing unit; FL2= Elipar FreeLight 2; O360= Optilux 360