Comparative Evaluation of Anchorage Loss Between Active Tie Backs and Coil Springs During Enmasse Retraction in Bimaxillary Protrusion Cases

Abstract

Aim: In orthodontics, applying forces to move teeth generates equal and opposite reactions on the anchorage units, potentially causing unwanted movement—a phenomenon known as anchorage loss. This can impede treatment outcomes by complicating anteroposterior corrections and affecting facial aesthetics. This study aims to evaluate and compare the degree of anchorage loss during en masse retraction in bimaxillary protrusion cases using two different Methods: active tiebacks and coil springs. Methods: Sixteen patients diagnosed with Angle's Class II bimaxillary protrusion were randomly assigned to two groups: one treated with active tiebacks and the other with coil springs. Lateral cephalograms were taken before en masse retraction (T0) and after space closure (T1) to measure changes in the position of the first molars and quantify anchorage loss. Results: Both groups exhibited anchorage loss during en masse retraction. However, the group using active tiebacks showed less anchorage loss compared to the coil spring group. Specifically, the mean distance from the pterygoid vertical (PTV) to the distal contact point of the upper first molar increased by 1.78 mm with active tiebacks, whereas it increased by 3.37 mm with coil springs. Conclusion: There was a statistically significant difference in anchorage loss between the two methods, with coil springs causing greater loss than active tiebacks. This suggests that active tiebacks may be more effective in minimizing anchorage loss during en masse retraction.