A Retrospective Investigation of the Effects and Efficiency of Self-ligating and Conventional BracketsMegha AnandChairperson of the Supervisory Committee: Greg J. Huang Department of Orthodontics Introduction: Marketing strategies for self-ligating brackets have focused on less need for extractions and faster treatment. Recent meta-analyses have not found these claims to be well supported, but they point out limitations of the current evidence. These meta-analyses also conclude that additional, well-designed studies are indicated to improve our evidence base. The purpose of this retrospective cohort study is to assess the effects and efficiency of treatment with self-ligating brackets compared to conventional brackets. A secondary purpose is to identify any pretreatment malocclusion characteristics associated with choice of either self-ligating or conventional brackets. Methods: Patients treated in the private offices of two practitioners who simultaneously used both self-ligating and conventional brackets were selected for this study. The self-ligating subjects were selected first, and for each subject, an age and gender matched subject was chosen from the respective office. The self-ligation subjects were consecutively treated adolescents and young adults (11-25 years-old) who completed comprehensive fixed appliance therapy between January 1, 2011 and April 31, 2012. Patients with craniofacial anomalies, surgical treatment, treatment with arch expansion using expanders, interdisciplinary treatment, and incomplete records were excluded. The outcome measures were changes in the intercanine width, intermolar width, and arch length for both arches, change in mandibular incisor inclination, final PAR score, percent PAR reduction, overall treatment time, total number of visits, number of emergencies, number of broken brackets, and other emergencies such as a wire sliding to one side or the loss of ligation. All measurements were performed on digital models or digital lateral cephalograms in a blinded manner. PAR scores were measured by two calibrated assessors and the average of the two scores were used. Data were analyzed using the independent sample t-test, chi-square or fisher exact test and linear regression analysis. Results: The final sample comprised 74 patients from Clinician 1, and 34 patients from Clinician 2. The two clinicians exhibited significant differences in treatment duration, as well as in treatment strategies, such as the use of the SureSmile technique. Therefore, the decision was made not to pool the data from the two offices. For Clinician 1, no significant differences were observed between self-ligating and conventional brackets for the outcomes described above, other than increased arch length in both arches in the self-ligating group. The self-ligation patients treated by Clinician 2 demonstrated a significant increase in transverse dimension, less percent reduction in PAR score, less treatment time, fewer visits, and more wire sliding emergencies compared to the conventional bracke...
