الفهرس 
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Abstract
Aim: The purpose of this randomized clinical trial is to compare the treatment effects of friction and frictionless mechanics during en-masse retraction of maxillary anterior teeth in adult patients
with bimaxillary dentoalveolar protrusion undergoing extraction of all four first premolars.
Methodology: Thirty patients were recruited and randomly assigned to two different retraction mechanics. Friction group, using NiTi coil springs or Frictionless group, using closing T-loops for en-masse retraction. Retraction started in all patients following first premolars extraction using miniscrews as a source of indirect anchorage. The rate of anterior segment retraction as well as the
dental, and soft-tissue changes were analyzed in both groups on digital models and lateral cephalograms taken before retraction and after space closure. At the end of the retraction phase,
every patient was asked to fill in a questionnaire regarding his experience during treatment.
Results: Statistically significant faster rate of anterior space closure was recorded in frictionless group in comparison to friction group with statistically significant shorter duration of retraction.
Similar dental and soft tissue changes were found in both groups, with no statistically significant difference, following en-masse retraction. Patients’ expectations and experiences were comparable
with no significant difference in both groups.
Conclusions: Both mechanics have successfully achieved the required treatment objectives in bimaxillary dentoalveolar protrusion patients requiring anterior retraction. However, faster rate
with shorter duration of retraction was found in frictionless group.