Shear bond strenght of three bulk-fill composites and conventional composites restorative material to dentine : In-vitro

The aim of this in vitro study is to assess the shear bond strength of different Bulk fill composites with two steps self etch adhesive system to dentin. Twenty extracted sound human molar teeth were selected and sectioned mesiodistally, then the substrate surfaces were roughened with 600- grit silicon carbide grinding paper to achieve flat homogeneous dentin surfaces and the samples were then equally and randomly divided into 4 groups, 10 samples for every group . The bonding system ( AdheSE, Ivoclar-Vivadent)was used in accordance with the manufacturer's instructions. A mould with a central cylindrical cavity (3 mm in diameter and 4 mm in height) was adapted on the specimen and filled with resin composite in two consecutive increments of 2 mm for the regular RC (Filtek™ Z250 3M/ESPE, St. Paul, MN, USA) and in one 4-mm increment for the bulk-fill RCs(Venus® bulk fill ,Heraeus Kulzer GmbH, Hanau, Germany), (SureFil SDR flow; Dentsply, Konstanz, Germany) and (everX Posterior GC, Tokyo, Japan), followed by polymerizing each increment for 20 s (Bluephase 20I; Ivoclar-Vivadent). Specimens were then stored for 24 h at room temperature in distilled water, and were then loaded in a universal testing machine. The statistical analysis of the results were performed by "Oneway Anova" and"Tukey HSD" tests (p<0.05). The highest mean value was for the control group (Filtek Z250 3M/ESPE, St. Paul, MN, USA),after that (SureFil SDR flow; Dentsply, Konstanz, Germany ),than (Venus® bulk fill ,Heraeus Kulzer GmbH, Hanau, Germany),and the last one was (everX Posterior GC, Tokyo, Japan). No significant differences were found between the different groups P=0,129 (p > 0.05).