Chemical Changes Associated with Increased Acid Resistance of Er:YAG Laser Irradiated Enamel

Table 1

Mean values and standard deviations of elements’ atomic percentages and the Ca/P ratio on the irradiated enamel surface by experimental groups and stages.

Element	Average value and standard deviation
	Group I: control		Group II: 100 mJ			Group III: 200 mJ			Group IV: 300 mJ
	Untreated surface	After acid dissolution	Before irradiation	After irradiation	After acid dissolution	Before irradiation	After irradiation	After acid dissolution	Before irradiation	After irradiation	After acid dissolution
Carbon C	8.04^A±6.36	8.76^A±4.75	9.31^A±5.10	5.64^B±1.87	14.34^C±7.76	7.66^A±5.06	0.52^B±1.80	10.82^A±3.32	20.81^A±9.15	0.94^B±2.24	11.26^C±6.05
Oxygen O	57.98^A±5.05	58.09^A±4.95	62.8^A±5.82	64.5^B±4.11	57.13^C±7.29	66.19^A±3.94	69.70^B±1.52	62.98^C±2.41	53.65^A±5.32	67.03^B±4.62	59.35^C±6.23
Phosphorus P	12.91^A±1.98	12.69^A±1.73	11.56^A±1.25	12.35^B±1.05	11.93^A±4.00	11.18^A±0.75	12.14^B±0.54	10.65^A±0.59	10.27^A±2.17	12.53^B±1.29	11.02^A±1.44
Chlorine Cl	0.41^A±0.08	0.37^A±0.10	0.31^A±0.05	0.34^A±0.05	0.32^A±0.09	0.32^A±0.04	0.30^A±0.15	0.32^A±0.03	0.27^A±0.07	0.16^A±0.17	0.26^A±0.13
Calcium Ca	20.67^A±6.19	20.10^A±6.71	16.02^A±2.65	17.17^B±2.39	16.24^A±5.64	14.65^A±0.98	17.34^B±1.11	15.15^A±1.13	15^A±4.09	19.34^B±3.24	18.10^C±2.79
Ca/P ratio	1.60^A±0.25	1.58^A±0.33	1.38^A±0.10	1.38^A±0.08	1.36^𝐴±0.10	1.31^A±0.02	1.43^B±0.08	1.42^B±0.07	1.45^A±0.15	1.54^B±0.12	1.65^C±0.20

Groups with different letters are significantly different (𝑃≤0.05).