###### Abstract  
Objective: This study compared the tooth movement patterns of a power arm and a lever jig during mandibular canine retraction into a premolar extraction space using skeletal anchorage. Methods: A finite element model was developed based on anatomical structures. A mini-implant was placed between the mandibular second premolar and first molar, and canine retraction was simulated using a power arm and a lever jig. The lever jig's vertical arm lengths were 6 mm, 8 mm, and 10 mm, corresponding to force application distances of 4.5 mm, 6.4 mm, and 8.2 mm from the archwire, matching the power arm. Finite element analysis was performed using linear mechanical properties and an explicit method. Results: With the power arm, increasing vertical length led to greater extrusion, while the posterior force remained unchanged. The lever jig also showed increased extrusion with length but to a lesser extent. Posterior force increased proportionally with the lever jig length. Initial displacement analysis showed greater extrusion and distal tipping with the power arm, while the lever jig suppressed extrusion and facilitated controlled tipping. Stress analysis revealed a more uniform periodontal ligament stress distribution with the lever jig. Conclusion: The lever jig minimizes extrusion and enhances force concentration posteriorly, promoting efficient distal movement.  
ing archwires with sufficient rigidity [4; 5; 6]. However, even with this method, complete prevention of vertical bowing remains challenging.  
Recently, a new device called the lever jig has been introduced, utilizing the principle of a first-class lever to enhance moment generation during retraction [7]. By adjusting the length of the jig, the moment-to-force ratio can be quantitatively controlled, allowing for more precise regulation of tooth movement dynamics.  
Finite Element Analysis (FEA) is a widely used computational tool in dentistry for evaluating the biomechanical behavior of dental materials, implants, prostheses, and craniofacial structures under various loading conditions. Its non-invasive nature enables effective treatment planning and enhances the design of dental restorations and devices. In orthodontics, FEA is extensively applied to analyze biomechanical responses related to tooth movement [8; 9; 10; 11; 12; 13; 14; 15; 16]. Previous studies have explored various strategies to control vertical bowing during canine retraction, including the use of power arms and rigid archwires. While these methods have demonstrated some effectiveness, they do not fully eliminate vertical bowing. The lever jig presents a promising alternative by enabling more precise control over force application, potentially improving the predictability and efficiency of canine retraction. This is because a greater moment can be expected through the interaction with the main archwire, rather than by using a power arm to approximate the force to the center of resistance of the tooth in a clinical setting.  
The objective of this study is to utilize FEA to (1) compare force transmission and stress distribution among different traction methods and (2) analyze the displacement patterns of the mandibular canine under various traction conditions, thereby assessing the effectiveness of the lever jig relative to conventional retraction techniques.