Table 2.

Influence of the etching time on the roughness of the enamel surface

Conditioning time	controls	2 min	2×2 min	2×3 min	2×4 min
Mean	3.26	3.49	2.83	2.99	3.64
Standard deviation	0.72	1.41	1.87	1.72	1.42
Median	3.14	3.22	2.91	3.88	3.46
Minimum	2.03	1.37	0.41	1.37	2.18
Maximum	4.49	6.39	6.86	6.81	6.88
25 % percentile	2.67	2.70	1.10	2.00	2.54
75 % percentile	3.68	4.65	4.21	5.31	4.42

All numbers are asfc values