Evaluation and comparison of the resistance to sliding of archwires in conventional and self-ligating brackets with varying degrees of second-order angulation

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2009 (Department of Orthodontics and Dentofacial Orthopedics).Includes bibliographic references: leaves 43-46.The purpose of this study was to investigate the resistance to sliding between self-ligating and conventional orthodontic brackets at varying degrees of second order angulation. The brackets were mounted on a steel plate at varying angles and three different archwire sizes were pulled through the bracket at each angle. An Instron machine measured the force required to slide the archwire through the bracket. The resistance to sliding was then compared between the self-ligating and conventional brackets for each archwire/second order angle combination. For each archwire size the resistance to sliding was initially less for the self-ligating bracket, but at greater second order angles the resistance to sliding was more for the self-ligating bracket as compared to the conventional bracket. The resistance to sliding for both brackets increased as the thickness of the wire increased. The elastomeric ring of the conventional bracket had a small but significant contribution to the resistance to sliding at each angle. The clip of the self-ligating bracket appeared to have a greater contribution to the resistance to sliding at the higher second order angles