Comparing bond strengths of brackets on primary teeth with 3 different primers

The purposes of this study were to: (1) examine the shear bond strengths (SBSs) of orthodontic brackets bonded to primary teeth with conventional, self-etching, and moisture-insensitive primers; and (2) evaluate the mode of bracket failure.

Seventy-eight human primary teeth were divided equally into 6 groups: (1) the enamel surface was etched, and a conventional primer was applied under dry conditions; (2) the enamel surface was dried, and a self-etching primer was applied; (3) the enamel surface was etched, and a moisture-insensitive primer was applied under dry conditions; (4-6) the same adhesives were used as those in groups 1 to 3, but before priming, each tooth was moistened. Metal brackets were bonded with adhesive. SBSs were measured using a universal testing machine, and the bracket/adhesive failure modes were evaluated with the adhesive remnant index.

A notable drop in bond strength and a high incidence of bond failure at the enamel-adhesive interface were found in group 4. There was no significant difference in mean SBSs among the other groups.

These adhesive systems under specific conditions enable us to use a primary tooth in the sectional bracket appliance as the anchor tooth, thus helping improve the outcome of early treatment for malocclusion.