Cuspal deflection and microleakage in premolar teeth restored with bulk-fill flowable resin-based composite base materials

Objectives: To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases. Methods: Twenty-four sound upper premolar teeth with Class II cavities were allocated to three groups (n = 8). Restoration of the teeth involved the placement of an RBC (GrandioSO) in eight oblique increments (Group A) or Groups B and C were restored to within 2 mm of the palatal cusp in a single increment with bulk-fill flowable RBC bases (SDR and x-tra base) before the two occlusal cavity increments were placed with GrandioSO. Buccal and palatal cusp deflections were recorded postirradiation using a twin channel deflection measuring gauge. Following restoration, the teeth were thermocycled, immersed in 0.2% basic fuchsin dye for 24 h, sectioned and examined for cervical microleakage. Results: The mean total cuspal deflection for the oblique incremental restoration technique was 11.26 (2.56) mu m (Group A) and 4.63 (1.19) mu m (Group B) and 4.73 (0.99) mu m (Group C) for the bulk-fill flowable RBC bases. A significant increase in the mean total cuspal deflection for the incrementally filled GrandioSO compared with the SDR (P = 0.007) and x-tra base (P = 0.005) restored teeth was evident. No significant difference in the cervical microleakage scores was recorded between groups AC (P > 0.05). Conclusions: The bulk-fill flowable RBC bases significantly reduced cuspal deflection compared with a conventional RBC restored in an oblique incremental filling technique with no associated change in cervical microleakage recorded. (C) 2012 Elsevier Ltd. All rights reserved.