Aim: To compare the adhesive potential, the mechanics implicated in adhesive failure, and the effect on the enamel of four brands of lingual brackets.
Methods: One hundred sixty premolars and four types of commercially available lingual brackets (STB, ORG, Magic, and Stealth) were selected. Forty brackets per manufacturer were used, half bonded directly and half indirectly. Each of these bonding groups was further subdivided: 10 brackets were bonded without treatment, while the other 10 were sandblasted. Thus, a total of four groups were created for each type of bracket: (a) sandblasted and directly bonded, (b) sandblasted and indirectly bonded, (c) not sandblasted and directly bonded, and (d) not sandblasted and indirectly bonded. Immediately after bonding, each bracket was tested for adhesion strength, and each appliance was then examined via electron microscopy to calculate the ARI.
Results: Statistical analysis showed a significant difference among the four bracket types; a general improvement in lingual appliance mechanical features provoked by sandblasting, albeit with some exceptions; and no significant effect of bonding method on the degree of bond strength. The ARI revealed that the most common area of adhesion crisis was at the adhesive-bracket interface.
Conclusion: Overall, STB brackets performed better, and sandblasting proved to be an efficient way of improving the mechanical features of lingual brackets. Bonding technique, on the other hand, did not seem to exert a great influence on bonding success, and the bracket-adhesive interface was identified as the area most prone to failure.