Bonding of stainless steel brackets to enamel with a new self-etching primer

The purpose of this study was to measure the shear bond strength of stainless steel brackets bonded to enamel in vitro with a recently developed self-etching primer (Transbond Plus Self Etching Primer, 3M Unitek, Monrovia, Calif). Forty-eight extracted human teeth were obtained and randomly divided into 4 groups of 12: (1) control group with a conventional etchant and separate primer, (2) experimental group with the self-etching primer, left for 15 seconds before bonding, (3) same as group 2, but with the primer left for 2 minutes before bonding, (4) same as group 2, but with the primer left for 10 minutes before bonding. For each group, stainless steel brackets were mounted onto the prepared enamel, stored for 24 hours at 37 degrees C, and tested in a testing machine with a crosshead speed of 1 mm/min. There was no significant difference in the bond strength between the 4 groups as determined by analysis of variance (ANOVA) (P <.05). Under the conditions of these experiments, a 10-minute delay in bonding after application of the self-etching primer might not be deleterious to adhesion.