Biomimetic Effect of Nano-Hydroxyapatite in Demineralized Enamel before Orthodontic Bonding of Brackets and Attachments: Visual, Adhesion Strength, and Hardness in In Vitro Tests

Table 2

Adhesion values of the six groups tested. Shear bond strength has been measured in MPa (conditions: untreated enamel, enamel after hypomineralization treatment, and enamel after hypomineralization and remineralization treatments).

Group	Appliance	Enamel	Mean	St Dev	Min	Mdn	Max	Significance
1	Bracket	Intact	20.73	8.97	10.02	18.78	37.87	A, D
2	Bracket	Demineralized	4.68	1.38	2.67	4.52	7.54	B
3	Bracket	Demineralized and remineralized	12.31	3.91	6.98	12.03	20.41	C
4	Attachment	Intact	27.82	3.61	20.09	28.08	34.12	A
5	Attachment	Demineralized	6.35	1.54	3.09	7.04	7.70	B
6	Attachment	Demineralized and remineralized	19.77	7.23	13.63	15.66	34.02	C, D

Tukey grouping-means with the same letters are not significantly different.