Shear bond strength of a self-etching primer after 10,000 and 20,000 thermal cycles.
OBJECTIVE
To determine the effects of thermocycling on shear bond strengths (SBSs) of a self-etching primer (SEP)after 10,000 and 20,000 thermal cycles. The tested hypothesis was that 10,000 and 20,000 thermal cycles would affect the bond strength of metal brackets bonded to enamel with the self-etching primer.


METHODS
Brackets were bonded to bovine incisors with two etching protocols. In group CM (conventional method), teeth were etched with 37% phosphoric acid for 30 s. In group SEP, a self-etching primer (Transbond Plus, 3M Unitek) was applied. Brackets were bonded with light-curing adhesive (Transbond XT, 3M Unitek). The SBSs were determined after water storage at 370°C for 24 h, after 10,000 and 20,000 cycles of thermocycling.


RESULTS
For both groups (CM and SEP), SBSs decreased with 10,000 and 20,000 thermal cycles. These decreased SBSs were significantly different from the values obtained with no thermocycling. Highest SBSs were observed with no thermocycling for groups CM and SEP (18.6 and 18.0 MPa, respectively). These values were not statistically different from each other. Lowest SBSs were obtained with 10,000 and 20,000 thermal cycles for group SEP (14.2 and 14.7 MPa, respectively). These values were significantly different from all other SBSs.


CONCLUSIONS
This study indicates that the SEP (Transbond Plus) provides clinically acceptable bond strength values compared with the conventional method after 10,000 and 20,000 thermal cycles.
Turk
Tamer
T
University of Ondokuz Mayis, Faculty of Dentistry, Department of Orthodontics, Samsun, Turkey.
Elekdag-Turk
Selma
S
Isci
Devrim
D
Cakmak
Fethiye
F
Ozkalayci
Nurhat
N
D000134:Acid Etching, Dental / Q000379:methods*; D000818:Animals; D002417:Cattle; D001840:Dental Bonding; D017005:Dental Debonding; D003743:Dental Enamel; D003799:Dental Stress Analysis; D006358:Hot Temperature; D008422:Materials Testing; D016910:Orthodontic Brackets; D010756:Phosphoric Acids; D011897:Random Allocation; D019279:Resin Cements; D033081:Shear Strength
D010756:Phosphoric Acids; D019279:Resin Cements; C429625:Transbond Plus Self-Etching Primer; C477790:Transbond XT; C030242:phosphoric acid