Table 3. Multivariate analysis of brackets exposed to different staining solutions: time and brand factors.

		Significance
	Coke	Coffee	Wine
Time (initial)	0.000	0.004	0.000
24 hours - 72 hours	0.363	0.007	0.000
72 hours - 7 days	0.801	0.002	0.002
7 days - 14 days	0.000	0.650	0.000
Time by brand (parallelism)	0.020	0.002	0.004
24 hours - 72 hours	0.486	0.478	0.018
72 hours - 7 days	0.525	0.009	0.012
7 days - 14 days	0.002	0.014	0.005
Brands	0.000	0.424	0.354

Coke: 1) Mauchly's sphericity test (p = 0.152); 2) non-significant Levene's test [?E1 (24 h) (p = 0.03); ?E2 (72 h) (p = 0.08); ?E3 (7 d) (p = 0.22); ?E4 (14 d) (p = 0.79)]. Coffee: 1) Mauchly's sphericity test (p = 0.001); 2) non-significant Levene's test [?E1 (24 h) (p = 0.58); ?E2 (72 h) (p = 0.37); ?E3 (7 d) (p = 0.32);?E4 (14 d) (p = 0.98)]. Wine: 1) Mauchly's sphericity test (p < 0.001); 2) non-significant Levene's test [?E1 (24 h) (p = 0.02); ?E2 (72 h) (p = 0.82); ?E3 (7 d) (p = 0.97); ?E4 (14 d) (p = 0.18)].