Table 3.

Mean (SD) and median of pre- and post-brushing gingival abrasions (GA) by brush group and GA increase group comparison, according to abrasion size: all, small (≤2 mm), medium (3 to 5 mm), large (>5 mm)

Brush (N)	GA mean (SD)/median		GA increase mean (SD)/median	P-value*
	Prebrushing	Post-brushing
All abrasions
Manual (90)	11.5(7.57)/10	26.6(12.49)/24.5	15.1(11.41)/12.5b	0.004
Power (91)	10.6(7.32)/8	21.1(8.89)/22	10.5(6.63)/10b
P-value	0.389†
Small abrasions (≤2 mm)
Manual (90)	10.7(6.85)/10	25.5(11.99)/24	14.8(11.28)/12b	0.005
Power (91)	9.9(7.01)/8	20.3(8.65)/20	10.4(6.61)/11b
P-value	0.380†
Medium abrasions (3 to 5 mm)
Manual (90)	0.6(0.98)/0	0.7(0.93)/0	0.2(0.83)/0c	0.773
Power (91)	0.4(0.84)/0	0.6(0.92)/0	0.2(0.58)/0d
P-value	0.263†
Large abrasions (>5 mm)
Manual (90)	0.3(0.54)/0	0.5(0.81)/0	0.2(0.65)/0d	0.005
Power (91)	0.2(0.55)/0	0.2(0.46)/0	0.0(0.39)/0e
P-value	0.269†

SD, standard deviation; CI, confidence interval.

^*P-value for group comparison using non-parametric ancova, with prebrushing GA as covariate.

^bSign test for change from pre- to post-brushing: ^bP < 0.001

^cP = 0.047

^dP = 0.002

^eP = 1.000.

^†Prebrushing group comparison: Wilcoxon rank-sum test.