An ex vivo assessment of a bonding technique using a self-etching primer.

Objective: This study assessed a new self-etch/priming system for use in orthodontic bonding.

Setting: An ex vivo study.

Method: Three groups of 20 extracted premolar teeth were bonded with metal orthodontic brackets. Group 1 was bonded with Transbond using the conventional technique (control). Group 2 was bonded using the new Transbond-Plus combined etch/primer system to wet enamel and Group 3 to dry enamel. The teeth were debonded using an Instron Universal Testing Machine. The mean debond force was calculated for each group and compared statistically. The teeth were examined under the stereomicroscope to assess the site of debond and adhesive remnant index.

Results: Group 2 (etch/primer on wet enamel) had the lowest mean debond value at 5.2 MPa. ANOVA and Tukey tests confirmed that the bond strength results of Group 2 were significantly lower than Groups 1 (P < 0.01) and 3 (P < 0.05). The enamel/resin interface was the commonest site of bond failure for both etch/primer groups (Groups 2 and 3). They had less retained resin and significantly (P < 0.001) lower ARI scores compared with Group 1 (control).

Conclusions: The results of this ex vivo study suggest that the self-etch primer should achieve adequate bond strengths when applied to dry enamel surfaces. In addition there should be less retained resin requiring removal at debond.