Enamel loss during bonding, debonding, and cleanup with use of a self-etching primer

Self-etching primers have recently been introduced to simplify the orthodontic bonding process. The aim of this investigation was to compare the enamel loss at each stage of the bonding and debonding process with the use of such a product compared with the conventional two-stage etching and priming process with 37% o-phosphoric acid. In the laboratory, a planer surfometer was used to measure enamel surface height before any enamel treatment, after pumicing, after etching, and once the brackets had been debonded, after enamel clean-up with one of 4 clean-up methods. The latter included a high-speed tungsten carbide bur, a slow-speed tungsten carbide bur, debanding pliers, and an ultrasonic scaler. A change in enamel surface height was seen at each stage of the bonding and debonding process. After pumicing and conventional etching, the cumulative median enamel loss was -2.76 mum; however, the range was from -1.11 to -4.57 mum. This observed loss was much less than in previous reports on enamel loss after acid etching. With the self-etching primer, the median enamel loss was significantly lower, at -0.27 mum (range, -0.03 to -0.74 mum). At debond, there was also a significant difference in the adhesive remnant index scores between the 2 groups, with more adhesive remaining on the enamel surface in the conventional-etch group. It was during enamel clean-up that most surface loss occurred. In both the conventional and self-etch groups, most enamel loss occurred after the use of the high-speed tungsten carbide bur or the ultrasonic scaler and least with the slow-speed tungsten carbide bur or the debanding pliers.