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

	Bracket type	Mean lower LII scores (SD)	Comparison between groups
			T statistics	P-value
T0-T1 difference	MBT	1.55 (0.76)	-2.86	0.009*
	Damon3 MX	2.66 (1.30)
T1-T2 difference	MBT	1.57 (0.73)	2.69	0.012*
	Damon3 MX	0.87 (0.69)
T2-T3 difference	MBT	1.06 (0.81)	2.89	0.008*
	Damon3 MX	0.36 (0.48)
T3-T4 difference	MBT	0.55 (0.45)	1.38	0.177
	Damon3 MX	0.37 (0.22)

*P<0.05.