Enamel surface appearance after various debonding techniques

Abstract

The quality of enamel surfaces after debonding of orthodontic brackets was assessed under clinical and experimental conditions by means of stereomicroscopy and scanning electron microscopy. Orthodontic attachments were direct-bonded with either of two diacrylate resin adhesives. After bracket removal with a ligature cutter, remnants of adhesive on the tooth surface were removed by means of various rotating instruments at low speed. A particular replica technique made it possible to make sequential assessments of step-by-step polishing procedures and directly follow the gradual reduction and possible disappearance of individual scratches in the microscope. The observable qualitative trait was assigned a score of from 0 to 4 according to a proposed enamel surface index system: 0 = perfect surface; 1 = satisfactory surface; 2 = acceptable surface; 3 = imperfect surface; 4 = unacceptable surface. The instruments tested yielded the following ESI scores (Table I): fine diamond bur, 4; sandpaper coarse and medium grit, 3, fine grit, 2; green rubber wheel, 3; spiral-fluted and plain-cut tungsten carbide (TC) bur, 1. With the first three instruments, it was not possible to obtain a satisfactory surface (score 1), regardless of subsequent polishing (Figs. 4 to 6). Thus, of the instruments tested, the most adequate results were obtained with the TC bur. This tool, operated at low speed, produced the finest scratch pattern (Fig. 3) and the least enamel loss (Fig. 7), and it was superior in accessibility to developmental grooves and other difficult-to-reach areas. The clinical significance of inducing scratches in teeth of adolescents was discussed in the light of “normal” enamel surface appearance at various ages, wear of teeth, and remineralization.