Assessment of external apical root resorption following En-masse and two steps retraction in maxillary protrusion cases: A randomized controlled clinical trial

Aim: The aim of this study was to investigate the degree of external apical root resorption (EARR) following En-masse retraction (EM) and compared it to two steps retraction technique (TS) using friction mechanics. Materials and Methods: Thirty adult female with maxillary protrusion were randomly allocated by a computer sequence generator with 1:1 allocation ratio. EM group (mean age = 17.7 ± 1.89 years) and TS group (mean age = 17.7 ± 1.77 years). Mini-screws were inserted followed by first premolars extraction then randomization was accomplished. Patients received treatment with either EM procedure or TS to close the extraction spaces after alignment and leveling with the same pre-adjusted fixed appliances. Pre- and post treatment CBCT images of both groups was used to evaluate the EARR from (T0) start of retraction till end of space closure (T1). Results: The data of 20 patients (10 in EM group and 10 in TS group) were analyzed. EARR was detected in both groups with more root resorption in EM group by total average decrease in root length by -1.14 mm while in TS group by -0.66 mm as an average decrease in root length. Conclusion: The difference in EARR between the study groups was statistically significant. The highest RR values were found in TS group to be -1.01 mm in upper left central (UL1), while the greatest RR in EM group to be -1.5 mm in upper left canine (UL3)

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

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. Keywords: Anterior segment retraction; friction; frictionless; T-loop; anchorage; CBCT