ABSTRACT
Objective To observe the effect of several residual adhesive methods on the enamel surface ,and conduct lab evalua-tion .Methods Sixty premolars extracted because of orthodontic treatment .And all the teeth were randomly divided into 3 groups . Group 1:tungsten carbide burs + silicon particles ;Group 2 :ultrasonic scaling + silicon particles ;Group 3:silicon particles ,each with 20 premolars .After underwent several methods ,the surface roughness differences ,operation time were determined and ob-served with the scanning electron microscope .And the result was statistically analyzed .Results There were significant differences in the surface roughness and operation time among the three groups (P<0 .05) ,The scanning electron microscope after polishing showed that the teeth surface had different degrees of injury ,the silica particles group had less superficial scratch .Conclusion The tungsten carbide burs and ultrasonic instrument for debonding before the silica particles had less superficial scratch .