Table 2. Comparison between the Damon3 MX and conventional MBT groups in the upper Little's irregularity index (LII) scores at the 4 treatment intervals: T0 = pretreatment and at the first (T1), second (T2), third (T3) and fourth (T4) month .

	Bracket type	Mean upper LII scores (SD)	Comparison between groups
			T statistics	P-value
T0-T1 difference	MBT	2.01 (0.62)	2.30	0.02*
	Damon3 MX	2.62 (0.83)
T1-T2 difference	MBT	1.36 (0.94)	1.15	0.25
	Damon3 MX	1.71 (0.67)
T2-T3 difference	MBT	1.01 (0.62)	0.24	0.81
	Damon3 MX	1.06 (0.64)
T3-T4 difference	MBT	0.57 (0.74)	0.30	0.75
	Damon3 MX	0.64 (0.53)

*P<0.05.