Effect of thermocycling on shear bond strength and mode of failure of bonded retainer using flowable composite resin

Jeon, Jae Ho; Son, Woo Sung

Abstract

The purpose of this study was to evaluate the effects of thermocycling on shear bond strength and mode of failure of orthodontic bonded retainer using flowable composite resin and to ascertain whether the flowable composite resin is useful for use as adhesive for orthodontic bonded retainers. One hundred and sixty freshly extracted human premolars were collected and eighty bonded retainer specimens were fabricated. They were randomly separated into 2 groups (Group G: general composite resin-CharmFil(R), Group F: flowable composite resin-CharmFil Flow(R), wire: Tri-flex(R)). Each group was divided into 2 subgroups (Subgroup 24: stored in water at 37 degrees C for 24 hours for baseline data, Subgroup T: stored in water at 37 degrees C for 24 hours and thermocycled between 5 +/- 2 degrees C and 55 +/- 2 degrees C for 500 cycles before testing the in vitro shear bond strength). Shear bond strength was measured and mode of failure was evaluated with a stereomicroscope. There was no statistical difference in shear bond strength and mode of failure between the bonded retainer using general composite resin and flowable composite resin. Therefore, in considering shear bond strength and mode of failure, it is sufficient to use flowable composite resin as resin adhesives for bonded retainers.