Factors that affect the shear bond strength of multiple component and single bottle adhesives to dentin

To examine the effects of thermocycling and the long-term integrity of the bonds between adhesive and resin composite to bovine dentin using multi-step and single bottle adhesive systems.

Dentin bonding sites were prepared using water irrigated #600 grit SiC paper on bovine incisor crowns mounted in acrylic resin. A 4 mm diameter area of dentin was etched, rinsed, left visibly moist and adhesives applied according to the manufacturers' instructions. The adhesives were: Scotchbond Multipurpose, Single Bond, All Bond 2, One Step, and Prime & Bond 2.1. Cylinders of Z100 resin composite 4 mm in diameter were positioned over the adhesive and visible light-cured. Bonded specimens were divided into five groups each containing 12 samples and: (1) stored in water for 24 hours; (2) stored in water for 7 days; (3) stored in water for 270 days; (4) thermocycled after 24 hours and stored for a total lapsed time of 7 days; (5) stored in water for 6.5 days, and thermocycled for a total lapsed time of 7 days. All storage temperatures were 37 degrees C. All specimens were shear (SBS) tested to failure at the end of each storage period, the results converted to MPa and the mode of fracture failure recorded.

The SBS for all five adhesives deteriorated over time; the effects of thermocycling were shown to be variable and dependant upon the adhesive; the modes of fracture failure were shown to be adhesive/cohesive or mixed; after long-term (270 days) storage there was an increased tendency for adhesive/cohesive fracture failure.