Table 1. Atomic Percentage Ratio of Enamel Treated with Different Types of MDP-Containing Adhesives Derived from XPS Analysis.

	atomic % ratio
sample group	Ca/P	C/Ca	O/Ca
UE	1.36	0.95	2.68
Etch	1.31	0.84	2.62
CSE-SE	1.07	2.72	3.18
SBU-SE	1.28	2.69	3.76
ABU-SE	1.19	2.18	2.86
CBQ-SE	1.18	2.02	3.85
EX-SE	1.26	1.22	2.70
SBU-ER	1.10	2.15	3.14
ABU-ER	0.77	8.70	5.11
CBQ-ER	0.53	64.83	29.38
EX-ER	1.03	3.38	3.25