Vourdouris JC. American Journal of Orthodontics & Dentofacial Orthopedics 1997; 111:119-143.
To compare the frictional resistance of active versus passive twin bracket systems.
A total of 83 orthodontic patients undergoing treatment with fixed appliances took part in the study. An in vivo clinical investigation with in vitro scanning electronmicroscopy was conducted to compare the frictional resistance of three different self-ligating bracket systems with 0.022 inch slots, active type A (Sigma*, American Orthodontics), passive type B (TwinLock*, Ormco Corp.), and passive type C (Damon™, Ormco Corp.) with three conventionally ligated twin counterparts, respectively types D, E, and F.
Active self-ligating brackets demonstrate less frictional resistance than conventionally ligated twin brackets and passive self-ligating twin brackets demonstrate far less frictional resistance than active.
With respect to the reduction in the amount of frictional resistance for various bracket types, the following was determined:
In regard to the manner in which archwires are secured to the brackets, the following was determined:
"This investigation produced scientific and clinical evidence showing that interactive twins, including the Damon appliance, are capable of kinetically interacting in a nondegrading manner with resilient archwires and without elastomerics or metal ligatures to create a new reduced friction standard for biocompatible tooth movement." Furthermore, this study showed the following: