SEM-evaluation of enamel surfaces after removal of fixed orthodontic appliances

To determine where, and how severe, the enamel surfaces were damaged by the removal of fixed orthodontic appliances, and whether the damage showed any change after 12 months.

284 teeth of 13 patients after orthodontic treatment were examined. Brackets had been bonded on incisors, cuspids and premolars, while first molars were banded. Replicas of the teeth were made immediately after the removal of the brackets and adhesive, and again 1 year later. SEM photographs at a magnification of x10 were taken of all of the labial enamel surfaces. Using a computer, a grid with 3 x 3 rectangles was superimposed onto the photographs. In every rectangle, at a magnification of x50, damage caused by debonding was graded with an index.

Moderate to heavy damage on the enamel surface was detected in 44% of all rectangles. More than 88% of all rectangles exhibiting damage showed no sign of improvement after 12 months. The more distal a tooth was in the dental arch, the more serious the damages turned out to be. More than 88% of the teeth had visible grooves in the line angle and/or cervical area, which must have been caused by tungsten carbide burs. In general, it was obvious that the middle of the labial surface, where the bracket was fixed, was not the area most affected, but rather the approximal and cervical borders.