Shear strength of orthodontic bonding agents.

The aim of this study was to compare the in vitro bond strength to enamel measured in shear of the light-activated bonding agent Heliosit-Orthodontic with the shear bond strength of the two-paste bonding resin Concise and the 'no-mix' bonding resin Right-On. In a number of separate tests involving 205 teeth and 267 bonds, the Heliosit-Orthodontic is shown to form a stronger bond to canine teeth than Right-On, but a weaker bond to molars. The HeliositOrthodontic also forms a weaker bond to molars than does Concise. Examination of the failed bonds suggests that when tested in shear the Right-On and the Concise tend to fracture at the enamel surface, whereas the Heliosit-Orthodontic fractures at the mesh-adhesive interface.