Canine Retraction Using Different Bracket Slots' Sizes: A Randomized Clinical Trial

Study Design This will be a multi-center randomized clinical trial.

Participants Participants will be recruited from subjects attending the Department of Orthodontics in the College of Dentistry, University of Baghdad and some private clinics seeking orthodontic treatment.

Sample Size Calculation Sample size will be calculated using G-power software based upon two previous trials (Mezomo et al., 2011; Moninia et al., 2019) investigating monthly canine retraction rate between conventional-ligated and self-ligating brackets. Using the highest SD and assuming the smallest difference requiring detection in canine retraction velocity to be 0.30 mm/month with an alpha level of 0.05 and power of 80%, a total of 13 canines will be required per group. Therefore, recruiting 13 patients in each group will provide 26 canines per group and this will account for dropout.

Participant Recruitment Patients seeking orthodontic treatment who meet the inclusion criteria will be assessed by the investigator for planning the orthodontic treatment. The patients will be invited to participate in the study and will be given a participant's and/or parents' information sheet to take home with them. Patients will be asked to decide about joining the trial on the next appointment (after at least one week).

Randomization and Sequence Generation Simple randomization will be accomplished with no stratification using a random number generator. A table for the allocation of the participants in the study will be composed (which includes the study number and allocation group) and kept in a sealed envelope. All the documents used for the randomization and allocation sequence generation will be kept away from the clinical environments.