Cuspal deflection and microleakage in pre molar teeth restored with bulk-fill resin-based composites

The aim of this study was to assess the cuspal deflection and cervical microleakage of premolar teeth filled with a bulk-fill composite resin or bulk-fill flowable composite resin base, and comparison between them and a conventional dimethacrylate and a silorane-base composite resin. Forty maxillary premolar teeth were divided into four groups (n?=?10), standardized large mesio-occluso-distal (MOD) cavities were prepared. The distance between cusp tips was measured before and after the cavity preparations with a digital micrometer. In Group 1 Quixfil was used with bulk-fill technique. Teeth in Group 2 were restored to within 2?mm of palatal cusp in a single increment with x-tra base. The remaining occlusal cavity was restored with GrandioSO. In Groups 3 and 4, the teeth were incrementally restored with GrandioSO and Filtek Silorane, respectively. Cuspal deflection was measured 5?min, 24?h, 1 week, and 2 weeks after the completion of restorations. Each restored tooth was subjected to thermocycling regime, and microleakage was assessed. Data were analyzed with Kruskal–Wallis and Mann Whitney U tests (p?<?0.05). Groups restored with bulk-fill composites (Groups 1 and 2) showed similar cuspal deflection with the group restored incrementally with GrandioSO. A significant reduction in cuspal deflection was observed in Filtek Silorane restorations. None of the groups showed complete prevention of dye penetration. Group 2 showed the best marginal sealing. In Conclusion, conventional composite resin applied by incremental technique caused cuspal deflection similar to that of bulk-fill composites used as restorative or base. The flowable bulk-fill composites were superior to others in preventing microleakage.