Evaluation of anchorage loss following anterior segment Evaluation of anchorage loss following anterior segment retraction using friction versus frictionless mechanics: a retraction using friction versus frictionless mechanics: a randomized clinical trial

Abstract

Objective: Evaluation of anchorage loss following anterior segment retraction (ASR) using friction versus frictionless mechanics when mini-screws are directly and indirectly loaded using Cone beam computed tomography (CBCT). Material and methods: Thirty females with bimaxillary protrusion were randomly allocated into two groups, friction and frictionless. In friction group, a hook was crimped on 0.017- by 0.025-inch stainless steel wire distal to the lateral incisor and elastomeric chain rendering 160 g/side extending between the hook and mini-screw implant to complete the ASR. In the frictionless group, canines were ligated to the mini-screws for indirect anchorage then ASR was done using closing T-loops fabricated from 0.017- by 0.025-inch titanium molybdenum alloy (TMA) wire rendering comparable retraction force. Analysis of first molar anchorage loss in terms of bodily and angular movement were assessed using cone beam computed tomographic (CBCT) images. Results: The use of mini-screws prevented significant anchorage loss in both groups and ASR was accomplished successfully. Anchorage loss in the form of angular tipping was of no statistical significance between friction and frictionless group. Conclusion: No advantage of either mechanics over the other regarding anchorage loading on the first permanent molars. Mini-screws are efficient devices to control the anchorage. Both direct and indirect mini-screw anchorage prevented first permanent molar mesial tipping and can be use alternatively.