The effect of changing crosshead speed on the shear bond strength of orthodontic bonding adhesive

OBJECTIVE: To examine the influence of different crosshead speeds on the in vitro shear bond strength and adhesive remnant index scores for the same orthodontic adhesive. MATERIALS AND METHODS: One hundred human molars were randomly allocated to four groups. Brackets (.022 inch Victory series, 3M, Monrovia, CA, USA) were bonded with Ortho Solo primer (Ormco, Glendora, CA, USA) and Enlight (Ormco, Glendora, CA, USA) adhesive paste to their buccal surfaces. The brackets were debonded with a universal testing machine (Instron, Canton, MA, USA) with each group subjected to a different crosshead speed of 0.5 mm/min, 1.0 mm/min, 2.0 mm/min and 5.0 mm/minute. Shear bond strength (SBS) was measured and enamel surfaces were examined to determine the adhesive remnant index (ARI) score. RESULTS: No significant differences were found between the mean SBS or ARI score for any of the groups. CONCLUSIONS: Studies using different crosshead speeds when testing identical adhesives may be used to compare the SBS of other orthodontic adhesives, provided the testing protocols are similar.