Table 2.

Mean and standard deviation of surface roughness (R_a) and of the largest distance between peaks and valleys (R_tm) found on the brackets' surfaces

		Condition
	New	12 months	24 months	P value *
Ra	0.79±0.15	0.85±0.36	1.17±0.39	n.s. 1,2,3
Rtm	2.04±0.33	2.66±1.23	4.29±1.07	p<0.05 2,3 /n.s. 1

^*P values were obtained by one way analysis of variance (one way ANOVA) followed by the Tukey post hoc test

n.s.=not significant (p>0.05)

¹New versus 12 months

²New versus 24 months

³12 months versus 24 months