Objective: To evaluate the effect of applying an adhesive, prior to different flowable composite resins, on the shear bond strength (SBS) of orthodontic brackets to acid-etched human enamel.
Materials and methods: One hundred metal brackets were bonded to 35% phosphoric acid-etched human premolars using four flowable composites (Admira Flow, Tetric Flow, Filtek Supreme, Transbond Supreme) and a conventional orthodontic composite resin (Transbond XT). For each experimental group, half of the specimens were bonded in combination with Transbond XT adhesive. After 24 hours of storage, an SBS test was performed. Adhesive remnant index scores were determined after the failure of brackets. Two-way analysis of variance and Student-Newman-Keuls multiple comparison tests were performed at P < .05.
Results: When using an adhesive system, the five composites performed equally. The application of adhesive had a significant effect on SBS. Without adhesive, SBS decreased in all groups, except for Transbond Supreme LV. All the test groups exhibited similar bracket failure modes.
Conclusions: When using an adhesive system, flowable composite resins exhibited similar SBS. Transbond Supreme was the only resin performing similarly with or without adhesive system application.