The aim of this
in vitro study was to evaluate the bonding durability both to enamel and dentin of three fluoride-releasing enamel/dentin adhesive systems-
experimental ABF and
Imperva Fluorobond as a 2-step type (self-etching primer+adhesive) and
Reactmer as a 1- step type (self-etching-priming-adhesive). The tensile bond strength was determined after 1 day in 37°C water, 360 days in 37°C water, and after thermocycling between 5°C and 55°C water for 5, 000 times. ABF showed high bond strength to enamel and dentin after 1 day. Bond strength in enamel was significantly degraded particularly by thermocycling, but fracture modes were almost all cohesive failures of bonding resins. Therefore, TBS values might be reflected by the tensile strength of bonding resin and real bond strengths at interface must be higher than the values obtained from the TBS tests.
Fluorobond indicated the similar dentin bonding durability to ABF, but bond strength to enamel was inferior. Adhesive failures were mainly observed in enamel: thereby bonding durability to enamel was insufficient. In
Reactmer, bond strengths both to enamel and dentin were significantly reduced by long-term water storage, and tensile fractured surfaces were cohesive failures of bonding/composite resin at all specimens. These findings suggest that the bonding resin of this system might degrade in water immersion with the passage of time.
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