The mean pain scores ( standard deviation ) were 2.63 ( 1.68 ) in the 2 % group , 2.08 ( 1.35 ) in the 3.5 % ; 2.00 ( 1.65 ) in the 5 % , 1.93 ( 1.40 ) in the 8 % and 1.83 ( 1.35 ) in the 12 % group .