Residual debris and bond strength-Is there a relationship?

A study was undertaken to test the theory that there is a relationship between bond strength at the separate interfaces of the direct bonding and the amount of residual debris remaining on the enamel surface following removal of a bonded appliance. In separate experiments, shear loads were applied at the complete direct bonding system and at the separate interfaces-namely, those at the adhesive/enamel and the adhesive/bracket base-using a chemically cured and a visible light-cured materials in combination with two designs of bracket bases. An assessment of residual debris following bond failure was made. For the complete direct bonding system, analysis showed that a foil mesh/chemically cured adhesive combination produces significantly more residual debris on the enamel than any other combination (P <0.05). No significant differences (P > 0.05) in shear bond strengths were detected for any bracket base/adhesive/enamel combination. Furthermore, no significant differences (P > 0.05) were detected between the shear bond strengths at the adhesive/enamel and adhesive/bracket base interfaces. These results suggest that the amount of residual debris following removal of the bonded bracket is not related to the shear bond strength at the separate interfaces but is governed by factors caused by bracket base design and properties of the adhesive used. © 1988.