EVALUATION OF BOND STRENGTH OF REPAIRS IN BULK FILL RESINS AFTER DIFFERENT PROTOCOLS OF ADHESION
Dental restoration repair; composite resins; adhesiveness.
With the development of Bulk Fill resins and the increased amount of restorations performed with this material, it is essential to study its repair characteristics. This study aims to evaluate the microtensile bond strength of repairs performed in bulk fill resins after artificial ageing, comparing different chemical surface treatments. 42 specimens will be elaborated (8x8x4 mm3) for each material, using color A1: a micro hybrid resin (Filtek Z250 XT – 3M ESPE, St. Paul, MN, USA) and a bulk fill resin (Filtek Bulk Fill – 3M ESPE, St. Paul, MN, USA) will be used. These specimens will be aged by storage in artificial saliva in stove at 37°C for 30 days, then they will receive a mechanical surface treatment through abrasion performed with a diamond bur. Next, they will be divided in six groups, according to the adhesion protocol to be followed. FSA – phosphoric acid 37% + Silane + Conventional adhesive; SA - Silane + conventional adhesive; FA – acid attack with phosphoric acid 37% + conventional adhesive; A – conventional adhesive; FU – phosphoric acid 37% + universal adhesive; U – universal adhesive. All specimens will be repaired with the resin Z250 XT, color A3, to differentiate from the materials to be repaired. The repaired resin blocks will be stored in distilled water for 24 h and then submitted to nanoleakage and microtensile tests. The specimens fractured will be evaluated with a stereomicroscopy to determine the type of fracture (adhesive or cohesive).