Evaluation of fourteen direct-bonding orthodontic bases.

Design characteristics (area of bonding, mesh size, and type) and bond strength of fourteen commercial direct-bonding metal bases with commercially attached brackets were evaluated. Tensile bond strength was measured with two direct-bonding adhesives, using plastic and natural teeth as substrates. Statistically significant differences in bond strength were observed among the bases, but bond strength was independent of nominal area and mesh size of the bases. Bond failures occurred most frequently at the base-adhesive interface of the metal bases. Damage caused by spot-welding of brackets to bases was implicated as a factor affecting bond strength.