Bonded resins in orthodontics.

JL he combination of acid-etching and bonding has led to dramatic changes in the practice of orthodontics. Newman began the revolution in orthodontics with the advent of epoxy-bonded attachments. Bonding has evolved and now is used for; placement of attachments, various types of retainers, and resin build-ups which address tooth size and shape problems encountered during orthodontic treatment. Initially, the bonding of orthodontic attachments was heralded for its numerous advantages (Figure 1). These advantages were specific for different treatment phases. During the initial strap-up of the patient there was less discomfort since separation and band seating were eliminated. Arch length was not increased by band material. Partially erupted teeth were bonded, and aberrant tooth shape did not result in difficult banding and poor attachment position. These advantages resulted in less chair time for the dentist and patient. During the active treatment phase, the appliance was more esthetic, not in contact with gingival tissue, and provided better access for cleaning. These factors provided the potential for better acceptance of the appliance, reduced incidence of caries, and better gingival health. When treatment was complete there was no band space to close and tooth size problems were more easily addressed by stripping or resin build-ups since interproximal areas were accessible. Several disadvantages soon emerged. Careful isolation of teeth during bonding was necessary to eliminate salivary contamination. Moisture control also made the bonding of partially erupted teeth exceedingly difficult. Some bonding agents were not sufficiently strong, while others would not bond to polycarbonate brackets. Better access for cleaning did not necessarily guarantee better hygiene, especially if resin was allowed to extend beyond the bracket base. The protection of interproximal enamel provided by well-contoured, cemented bands was absent. Finally, the best method for removal of resins from the tooth surface following treatment was not clear — nor were the ramifications of any remaining resin. This paper will discuss the use of resin bonding in several aspects of clinical orthodontics and critical variables related to these procedures.