Tensile and shear strength of orthodontic bracket bonding with glass ionomer cement and acrylic resin. An in vitro comparison.

The tensile and shear strength for a polyalkeonate luting cement (AquaCEM) and a no-mix acrylic resin (Unite) in orthodontic bracket bonding were compared in an in vitro test. Brackets bonded/cemented to extracted premolar teeth were subjected to loads in a universal testing apparatus and the dislodging forces were recorded. The possible influences of setting time and of bracket base design were also studied. No significant differences between the cement and the resin were found after allowing 24 hours of setting time. This in contrast to the significantly stronger tensile strength but inferior shear strength for the polyalkeonate cement when stress was applied after 15 minutes. A significantly higher tensile strength value was recorded for a foil-meshed bracket base type compared to an integral base type with cut grooves after 15 minutes, but not after 24 hours. While the polyalkeonate cement adhesion mostly fractured within the cement layer, the acrylic bond more often failed in the enamel-adhesive interface. The results support the use of the fluoride-containing cement as an alternative to acrylic adhesives in orthodontic bracket bonding, especially in high-risk caries patients.