Effects of cyclic loading on the bond strength of metal orthodontic brackets bonded to a porcelain surface using...

To evaluate cyclic and static shear bond strengths (SSBSs) of metal orthodontic brackets bonded to a porcelain surface using different conditioning protocols.

A total of 100 feldspathic porcelain disks were fabricated. The specimens were divided into four equal groups. Porcelain surfaces were conditioned with different protocols. In group 1, hydrofluoric acid and Embrace First-Coat primer were used. In group 2, hydrofluoric acid and silane were utilized. In groups 3 and 4, sandblasting with aluminum oxide powder was done instead of etching. Metal brackets were bonded to the porcelain surfaces using Transbond XT adhesive. SSBS testing was carried out in 10 specimens, while cyclic shear bond strength (CSBS) testing was done in 15 specimens from each group. The data were subjected to analysis of variance, least significant difference post hoc, and Student's t-tests.

Embrace First-Coat and silane exhibited a comparable SSBS. The sandblasting process significantly increased SSBS. No significant difference was found in bond SSBS utilizing either hydrofluoric acid and Embrace First-Coat or sandblasting and silane. With regard to CSBS, the use of sandblasting and Embrace First-Coat revealed the highest significant CSBS value, followed by sandblasting and silane. Etching with hydrofluoric acid prior to application of either primer exhibited the least CSBS values; however, no significant difference was found between them. The SSBS was significantly higher than CSBS.

Embrace First-Coat could be used successfully as an alternative to silane. Sandblasting provides higher bond strength than did hydrofluoric acid. Cyclic loading significantly decreased bond strength.