Evaluation of the rate of en-masse retraction in adults and adolescents with maxillary protrusion using friction versus frictionless mechanics A randomized clinical trial / By Leena Alaa Shibl, B.D.S. Future University in Egypt, 2015

Supervisors, Prof. Dr. Yehya A. Mostafam DDS, FDS, RCSEd, MSc, PHD, FPFA, FACD, Professor of Orthodontics and Craniofacial Orthopedics, Faculty of Oral and Dental Medicine, Future University, Prof. Dr. Amr R. El-Beialy, BDS, MSc, PhD, M Orth, RCSEd (UK), Associate Professor of Orthodontics, Faculty of Dentistry, Cairo University, Dr. Heba M. Dehis, BDS, MSc, PhD, M Orth, RCSEd (UK), Lecturer of Orthodontics, Faculty of Dentistry, Cairo University

Thesis (M.Sc.)-Future University in Egypt, Faculty of Oral and Dental Medicine, Department of Orthodontics, 2022

Includes bibliographical references.

Orthodontists, as well as their patients are greatly concerned about the duration of orthodontic treatment. To this day, there are several techniques being developed and tried over to shorten the duration of orthodontic treatment. The most time-consuming phase in orthodontic treatment is found in extraction cases. This study was carried out to investigate the rate of en-masse retraction using friction or frictionless mechanics. Digital models as well as CBCTs were used in this study as means for investigation.
The sample size was calculated and resulted in 15 participants per activation group. Each patient was randomly allocated to one of the intervention mechanics, either friction or frictionless. After dropouts, the results of 24 patients requiring 1st premolar extraction with maximum anchorage were included.
The steps of intervention included bonding the fixed appliance followed by levelling and aligning until 0.017x0.025” stainless steel wire. TADs were placed inter-radicularly between the first molar and the second premolar. Once anchorage was secured, patients were referred for first premolar extraction and the uptake of pre-intervention records (photographs, CBCT, and Impressions)
In the friction group, 8 mm crimpable hooks placed distal to the laterals was attached to a 0.017x0.025” stainless steel wire. Powerchains with a force of approximately 212g extended from these hooks directly to the TADs.
In the frictionless group, T-Loops were fabricated from 0.017x0.025” TMA (Titanium Molybdenum Alloy) wires, according to the design by Burstone. An activation of 4 mm created about 212g of force per side. The posterior segment was consolidated with a 0.017x0.025” stainless steel wire, with a ligature wire twisted between the miniscrew and the second premolar.
Patients were recalled every 4 weeks, where impressions were taken in order to measure the rate of retraction. Cases were considered complete when normal overjet was achieved, class I canines were attained, and extraction spaces were closed. On completion, patients were sent for the uptake of the final CBCT radiographs, impressions, and photographs.
Within the limitations of this study, the following can be concluded from the results produced:
1. In both groups, the rate of retraction gradually decelerated monthly. However, there was a statistically insignificant difference between the friction and frictionless mechanics in the rate of en-masse retraction
2. Statistically insignificant results were found when comparing the total amount of retraction between the two groups.
3. The 3D measurements of the final position of the 6 anterior teeth regarding the tip, torque, and vertical position were statistically insignificant.
4. Significant linear anchorage loss occurred in both groups, in accordance to the cast and CBCT measurements, with greater anchorage loss found in the Frictionless group. Angular anchorage loss was statistically insignificant
5. Root resorption occurred in the six anterior teeth, with the upper laterals showing the most amount of root resorption. However, these results were statistically insignificant between the groups.
6. Statistically insignificant pain experienced between the two groups, except during activation 1 and 6. Pain was experienced more by the frictionless group during the first activation, and more in the friction group during the sixth activation.

Text in English, abstracts in English and Arabic.