The effect of etch time and debond interval upon the shear bond strength of metallic orthodontic brackets.

Groups of orthodontic brackets were attached to enamel after etching for 15, 30 or 60 seconds. They were debonded by shear forces after 5 or 15 minutes, or 24 hours. The 15 seconds etch/5 minutes debond time specimens had much lower shear strengths than other groups. Sixty-second specimens showed evidence of tooth surface damage after debonding. Fifteen seconds of etching is therefore recommended routinely for bonding brackets. If a bracket is to be ligated within 5 minutes of placement, 30 seconds etching is recommended. A 60-second etch is considered too severe and should not be used.