| Abstract
Introduction: Achieving proper bond strength is an important objective in orthodontics, since bracket
replacement is a costly and time consuming procedure. Bond failures depend on multiple factors such as
etching process, primer application approach and masticatory forces. The aim of this study was to evaluate
the effect of elapsed time between primer application and bracket transfer on the shear bond strength of the
brackets bonded with no-mix composite.
Materials & methods: One hundred intact bovine incisors were randomly divided into 4 groups (n=25).
Brackets were bonded immediately after primer application in the first group and 5, 15, 30 minutes after
primer application in the second, third, and fourth groups, respectively. A universal testing machine was
used for debonding and measuring shear bond strength, and the failure sites were inspected under a
stereomicroscope. One way ANOVA plus Tukey tests and Chi-square test were used to evaluate shear bond
strength and adhesive remnant index(ARI), respectively.
Results: Differences in shear bond strength among four groups were significant (p=0.001). The differences
in shear bond strength between the first and second groups (p=0.011) and between the second and fourth
groups (p=0.002) were significant with greater bond strength mean value for the second group. ARI
evaluation showed significant differences among groups (p=0.032).
Conclusions: It could be recommend not to delay bracket positioning more than 5 minutes after primer
application, in order to avoid negative effects of elapsing time on the |