Power Arm 역학을 이용한 상악 전치의 치체 이동 증례

Bodily Retraction of the Maxillary Anterior Teeth with Power Arm Mechanics: A Case Report

Premolar extraction is often employed to enhance the facial profile in patients presenting with lip protrusion. However, during the retraction of incisors, a reduction in maxillary incisor torque is commonly observed. When the pretreatment incisor torque falls within the normal range, such a reduction may lead to suboptimal esthetic and functional outcomes. Therefore, preserving appropriate incisor torque throughout the retraction process is essential. This case report outlines the theoretical principles and clinical application of bodily retraction of the maxillary incisors. A 28-year-old female patient presented with a protrusive lip profile, dental crowding, and a Class II skeletal pattern. Given that her maxillary incisor torque was within normal limits, maintaining this torque during premolar extraction treatment was a primary objective. To achieve controlled retraction while preserving incisor torque, a long power arm was attached to the archwire distal to the canine. This configuration allowed the retraction force to pass through the center of resistance of the maxillary incisors, facilitating bodily movement rather than uncontrolled tipping. Post-treatment evaluation revealed successful bodily retraction of the maxillary incisors, accompanied by a marked improvement in the patient’s lip profile. This case highlights the clinical efficacy and predictability of using a long power arm to maintain incisor torque during orthodontic retraction, particularly in patients with initially normal incisor inclination.