Efficiency of self-adhering flowable resin composite and different surface treatments in composite repair using a universal adhesive

Aims: The aim of this in vitro investigation was to evaluate the efficiency of self-adhering flowable resin composite (Vertise Flow, Kerr, Orange, CA, USA) and different surface treatments in the repair microtensile bond strength (mu TBS) of aged nanofill resin composites using a universal adhesive. Materials and Methods: Aged substrates (x5000 thermocycling) were prepared using a nanofill (Filtek Ultimate; 3M ESPE) resin composite and randomly assigned to different surface treatments: (1) no treatment (control), (2) acid etching with 37% phosphoric acid, (3) Al(2)O(3)sandblasting, and (4) sandblasting with CoJet (3M ESPE). After surface treatment, specimens were further divided into two groups: no universal adhesive application and universal adhesive application. Vertise Flow was added to the substrates at 2-mm layer increments to a height of 5 mm and light cured. Restored specimens were sectioned to obtain 1.0-mm(2) beams for mu TBS testing. Data were analyzed with two-way analysis of variance and Tukey's honest significant difference tests (P < 0.05). Results: The lowest mu TBS values were recorded in the control and acid etching groups with no universal adhesive application (P < 0.05). Universal adhesive application significantly increased the repair mu TBS values of all surface treatments (P < 0.05), except CoJet treatment. There were no significant differences between Al(2)O(3)sandblasting, CoJet application, and acid etching groups with the universal adhesive application (P > 0.05). Conclusion: Vertise Flow can be used effectively in the repair of old nanofill resin composites. The usage of universal adhesive with prior acid etching to obtain acceptable repair performance would be the practical choice under clinical conditions.