Table 1. Bracket failures of both materials at indicated time points (n = 60).

Time point	Number (rate) of bracket failures		χ 2	p value
	RMGIC (n = 60)	RMD (n = 60)
T1	2 (3.3%)	3 (5%)	0.209	0.647
T2	1 (1.7%)	1 (1.7%)	0	>0.999