Shear bond strength of four orthodontic bonding systems.

Recently new orthodontic bonding systems have been developed for attachment of brackets to the etched facial surfaces of teeth. Two of these new systems use bonding agents that contain solvents. It is claimed that this improves the polymerization of the unfilled resin primer and may increase bond strength. A new light-cured restorative enamel/dentin-bonding agent has also recently been introduced. Its value in orthodontic bonding has not been determined. The aim of this investigation was to evaluate the shear bond strengths of the three new bonding systems and to compare these with a conventional orthodontic bonding system. Forty-eight enamel specimens were prepared with 600-grit silicone carbide paper, acid etched with 37% phosphoric acid, and assigned to four enamel-bonding treatment groups: (A) Saga sealant; (B) Maximum Cure; (C) Scotchbond-2; and (D) Concise enamel bond. After enamel priming, the specimens were bonded to Concise orthodontic bonding resin. The bonded specimens were thermocycled (15 degrees C to 45 degrees C) and then stored in distilled water at 37 degrees C for 7 days. Shear bond strength was tested with an Instron testing machine at a strain rate of 0.02 in/min. The mean shear bond strengths and standard deviations reported in MN/m2 were (A) 20.34 (5.37); (B) 25.33 (5.96); (C) 14.59 (5.25); and (D) 20.13 (4.98). The mean shear bond strengths for groups A, B, and D were significantly greater (p less than 0.05) than that for group C. The addition of solvents to the new orthodontic bonding systems does not appear to have a clinically significant effect. The new restorative bonding resin does not provide comparable enamel bond strengths.