EFFECT OF STORAGE ON MICRO TENSILE BOND STRENGTH OF VARIOUS TYPES OF FLOWABLE COMPOSITE

Abstract

The aim of the study is to investigate the effect of storage on micro-tensile bond strength of two self- adhesive flowable resin composites (Vertise Flow & Fusio Liquid Dentin) compared to conventional flowable resin composite (Filtek flow Z350 XT). Materials & Methods : Fourty-five extracted sound human molars were selected for this study. They were divided into three groups of fifteen each according to the type of resin composite used. The three main groups were further sub-divided into three subgroups of five each according to the storage time either twenty-four hours, three months and six months storage in distilled water. Each tooth was mounted on the cutting machine and sectioned into a series of 1 mm thick slabs under water cooling, then, by rotating the tooth 90° and again sectioning it lengthwise, sticks of 1.0 mm2 cross-section area were obtained. The central sticks from each specimen were selected and attached to the specially designed attachment jig, which was mounted on a universal testing machine. Data were recorded using computer software. A tensile load was applied via testing machine at a crosshead speed of 0.5 mm/min. The applied tensile force resulted in de bonding along the substrate-adhesive interface. The load (Newton) required for de bonding of each stick was divided by the area to express bond in MPa. Results : Filtek Z350 XT showed the highest mean micro-tensile bond strength, Vertise flow came next with the lowest mean microtensile bond strength values for the Fusio Liquid Dentin. Conclusion : The conventional etch and rinse flowable resin composite (Filtek Z350 XT) remains the gold standard of all other types of the flowable resin composites. The bond stability of the self-adhesive flowable resin composites was questionable after aging for three months and was adversely affected after six months.