Shear bond strength comparison of a conventional and a self-etching fluoride-releasing adhesive following...

To compare the effect of thermocycling on the shear bond strength of brackets bonded using different primers.

One hundred twenty extracted defect-free premolars were randomly divided into three groups. In all three, Transbond XT was the bonding adhesive of choice. In the control group (I), the standard Transbond primer was used, in group II a fluoride-releasing primer (Reliance fluoride containing light cure bond), and in group III an antimicrobial fluoride-releasing self-etching primer (Clearfil Protect Bond). These three groups were divided into two subgroups of 20 teeth each. In the first subgroups, the teeth were stored in only distilled water for 24 hours, whereas in the second subgroups, they were thermocycled 500 times between 5 degrees C and 55 degrees C. The shear bond strength was determined with a universal testing machine. After bracket failure, the Adhesive Remnant Index (ARI) score was verified. The data were analyzed using two-way analysis of variance, Bonferroni, and chi-square tests.

The group with the antimicrobial fluoride-releasing self-etching primer had a significantly lower shear bond strength than all other groups (P<.05). Thermocycling reduced the shear bond strength in all groups considerably.

The antimicrobial fluoride-releasing self-etching primer performed comparably worse regardless of thermocycling. Brackets attached with self-etching primers demonstrated a shear bond strength after thermocycling approaching the border of acceptable adhesion. Thermocycling changed the ARI scores of the self-etching primer groups from the bracket-adhesive to the enamel-adhesive interface.