Effects of rotary brush active application on enamel etching patterns of self-etch adhesive systems

Aim: The aim of the present study was to assess the effects of rotary brush active application technique on the ultramorphological changes induced by self-etching adhesive systems on ground enamel. Materials and methods: Three application methods were deployed: (1) passive application; (2) manual active application; (3) rotary-brush active application. Two self-etching adhesive systems were used: (1) Optibond All-in-one; (2) Nova Combo Plus. Acid-etching of the ground enamel surface with phosphoric acid was used as control. Labial surfaces of bovine incisors were separated into four pieces. One of three application methods including phosphoric acid-etching was used to apply one of self-etch adhesive systems to enamel surface of each enamel piece respectively. Treated enamel samples were then processed for evaluation under scanning electron microscope (SEM). Results: SEM findings showed that acid-etching completely removed the smear layer from the ground enamel surface. None of the active application techniques, however, were able to eliminate the smear layers. Conclusions: Active application of self-etch adhesives to enamel with a rotary brush may not have an effect on the interaction of the tested self-etch adhesives with smear layers on the enamel surface.