Table 2. Comparison of the microleakage grade scores among different groups.

Groups	Microleakage score, n (%)					P-value
	0	1	2	3	4
Fisher's exact test was used to compare the differences in treatment outcomes. aCompared with the control group; bcompared with the 35% H3PO4 30 s + SB2 group. Bold values indicate P<0.05. SBU: Single Bond Universal; SB2: Single Bond 2.
Control	0	0	1 (10)	5 (50)	4 (40)
SBU	0	1 (10)	4 (40)	3 (30)	2 (20)	0.265a
35% H3PO4 15 s + SB2	0	4 (40)	5 (50)	1 (10)	0	0.004 a
35% H3PO4 15 s + SBU	0	5 (50)	3 (30)	1 (10)	1 (10)	0.015 a
35% H3PO4 30 s + SB2	0	4 (40)	3 (30)	2 (20)	1 (10)	0.020a
35% H3PO4 30 s + SBU	3 (30)	7 (70)	0	0	0	0.001a, 0.044b