The bond strength of highly filled flowable composites placed in two different configuration factors.

Objective: The aim of this study was to evaluate the microtensile bond strength (μTBS) of different flowable composite resins placed in different configuration factors (C-factors) into Class I cavities.

Materials And Methods: Fifty freshly extracted human molars were divided into 10 groups. Five different composite resins; a universal flowable composite (AeliteFlo, BISCO), two highly filled flowable composites (GrandioSO Flow, VOCO; GrandioSO Heavy Flow, VOCO), a bulk-fill flowable composite (smart dentin replacement [SDR], Dentsply), and a conventional paste-like composite (Filtek Supreme XT, 3M ESPE) were placed into Class I cavities (4 mm deep) with 1 mm or 2 mm layers. Restored teeth were sectioned vertically with a slow-speed diamond saw (Isomet 1000, Buehler) and four micro-specimens (1 mm × 1 mm) were obtained from each tooth (n = 20). Specimens were subjected to μTBS test. Data were recorded and statistically analyzed with two-way analysis of variance and Tukey's post-hoc test. Fractured surfaces were examined using a scanning electron microscope.

Results: The μTBS in SDR-1 mm were higher than other groups, where Filtek Supreme XT-2 mm and GrandioSO Flow-2 mm were lower. No significant differences were found between C-factors for any composite resin (P > 0.05).

Conclusion: Bulk-fill flowable composite provided more satisfactory μTBS than others. Different C-factors did not affect mean μTBS of the materials tested.