[Comparison of 1-stage orthodontic bonding systems and 2-stage bonding systems: a review of the literature and the results of a randomized clinical trial].

Objective: The main objectives of this study are to present a literature review of self-etching primer's (SEP's) and present the outcomes of a prospective clinical trial 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 a control adhesive (Transbond). 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: Orthodontic Department Countess of Chester Hospital, 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) 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 (relative risk 0.47%; 95% confidence interval 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. The literature on SEP's supports the findings of this study.