Table 2.

Means (standard deviations) of Vickers hardness number (VHN) of the lower 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	25.2 (0.6)Aa	24.7 (0.9)ABa	23.8 (1.1)BCa	23.4 (0.9)Ca	21.4 (1.2)Ca
O360	16.1 (0.9)Ab	15.3 (0.7)ABb	14.4 (0.9)BCb	13.5 (0.9)CDb	13.2 (0.7)Db

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