Handling characteristics of precoated and operator-coated brackets.

introduced in 1991 to save the clinician the time spent in preparing the adhesive for direct bonding and applying it to the bracket.1 The APC brackets, which are packaged in individual capsules for ease of identification and infection control, are applied with finger pressure.2 A uniform factory precoating purportedly ensures an even amount and consistency of composite beneath each bracket. Any excess composite is expelled in a thick consistency from the bracket margins, so that it is easily identified and can be removed without altering the bracket position.3,4 Unlike chemically cured adhesives, the APC system provides virtually unlimited positioning time, because the adhesive does not set until it is lightcured. The improved control of the APC bracket and adhesive has been shown to make bond strength more reliable and reduce bond failures.5,6 The composite is a modified form of Transbond XT,* whose viscosity was increased in the original APC and reduced for the APC II. A less viscous adhesive may flow more evenly on the tooth surface and integrate more completely into the undercuts of the bracket mesh, thus improving mechanical retention. Light-cured composites differ in handling characteristics, such as the pressure needed to seat the bracket and the amount of bracket mobility during the removal of excess composite. To our knowledge, no studies have been carried out on the handling characteristics of APC brackets. This article reports the results of such an investigation.