A scanning electron microscopy comparison of enamel polishing methods after air-rotor stripping

In the last few years, orthodontic literature has shown particular interest in the interproximal enamel reduction technique described as stripping or slenderizing. Most researchers have shown, by scanning electron microscopy (SEM) studies, the difficulties encountered while attempting to remove coarse abrasions left after stripping with the first instrument. The objective of this SEM study was to compare the different polishing methods proposed in the literature and to assess the efficiency of our own procedure. For this purpose, 48 healthy human teeth (premolars and molars) were used after removal for orthodontic or periodontal reasons. The teeth were divided into eight groups of six teeth each (two molars and four premolars), and mounted on a typodont to simulate a clinical situation. Each group underwent stripping according to one of the following techniques: 18-blade tungsten carbide bur and fine and ultrafine diamond burs; coarse diamond bur and fine and ultrafine diamond burs; coarse diamond disk and Sof-Lex disks (Dental products/3M, St. Paul, Minn.); 16-blade tungsten carbide bur and phosphoric acid on finishing strip; and 8-straight blade tungsten carbide diamond bur and Sof-Lex disks. The SEM investigations demonstrated that it is not possible to eliminate, with normal polishing and cleaning methods, the furrows left on the enamel both by the diamond burs and the diamond disks and the 16-blade tungsten carbide burs. Mechanical and chemical stripping as well did not prove to be effective. By contrast, with the use of a 8-straight blade tungsten carbide bur followed by Sof-Lex disks for polishing the enamel, it is possible to obtain well-polished surfaces that many times appear smoother than the intact or untreated enamel.