A randomized clinical trial comparing 'one-step' and 'two-step' orthodontic bonding systems

Objective: The primary objective of this prospective clinical trial was to assess the clinical bond failure rates of orthodontic brackets bonded using a self-etching primer (SEP), compared with brackets bonded using a conventional acid-etched technique with control adhesive (Transbond (TM)). A secondary aim was to investigate whether characteristics of the operator, patient or tooth bonded had any influence on bracket failure. Design: Single-centre randomized controlled clinical trial. Thirty-four patients were bonded, each being randomly assigned to either the test or control adhesive. Setting: NHS Hospital Orthodontic Department, Chester, UK. Subjects: Orthodontic patients requiring fixed appliance treatment. Main outcome measures: Bond failure. Main outcome results: Failure rates over the initial 6-month period were 2.0% (Transbond (TM)) and 1.7% (SEP) with no statistically significant difference between the two groups. Over the duration of the fixed appliance treatment, bond failure rates increased, but remained acceptable at 7.4 % (TB) and 7.0% (SEP), respectively. When operator, patient and tooth characteristics were analysed, only the bracket location was found to be significant. Maxillary brackets were more likely to fail than mandibular brackets (RR 0.47%; 95% CI 0.22, 1.03). The failure rate for brackets in our study was low when compared with previous studies. Conclusions: Both the acid-etched control and self-etching primer in combination with adhesive pre-coated brackets were successful for clinical bonding. Their combined failure rate was lower than that reported in similar trials.