Residual acrylic adhesive after removal of plastic orthodontic brackets: a scanning electron microscopic study.

After etching for one minute with 35 per cent phosphoric acid, thirty-eight permanent teeth were furnished with plastic brackets. An additional twelve teeth were used as references and were etched but were not furnished with brackets. Four teeth served as untreated controls. Eight brackets had fallen off one week later. The remaining brackets were removed with various instruments. All the teeth were extracted and examined by scanning electron microscopy (SEM). On all of the teeth originally furnished with brackets, residual acrylic was found on the tooth surface. The SEM examination was supplemented with energy-dispersive x-ray analysis (ED) which confirmed that the observed residues differed in their chemical composition from the dental substance.