Palatal en-masse retraction of segmented maxillary anterior teeth: A finite element study
박재현, 국윤아, Kojima Yukio, Yun Sun-Ock, 채종문,
소속 상세정보
박재현 ( Park Jae-Hyun ) - A.T. Still University Arizona School of Dentistry & Oral Health Postgraduate Orthodontic Program
국윤아 ( Kook Yoon-Ah ) - Catholic University Seoul St. Mary’s Hospital Department of Orthodontics
( Kojima Yukio ) - Nagoya Institute of Technology Department of Mechanical Engineering
( Yun Sun-Ock ) - Private practice
채종문 ( Chae Jong-Moon ) - Wonkwang University School of Dentistry Wonkwang Dental Research Institute
Abstract
Objective: The aim of this finite element study was to clarify the mechanics of tooth movement in palatal en-masse retraction of segmented maxillary anterior teeth by using anchor screws and lever arms.
Methods: A three-dimensional finite element method was used to simulate overall orthodontic tooth movements. The line of action of the force was varied by changing both the lever arm height and anchor screw position.
Results: When the line of action of the force passed through the center of resistance (CR), the anterior teeth showed translation. However, when the line of action was not perpendicular to the long axis of the anterior teeth, the anterior teeth moved bodily with an unexpected intrusion even though the force was transmitted horizontally. To move the anterior teeth bodily without intrusion and extrusion, a downward force passing through the CR was necessary. When the line of action of the force passed apical to the CR, the anterior teeth tipped counterclockwise during retraction, and when the line of action of the force passed coronal to the CR, the anterior teeth tipped clockwise during retraction.
Conclusions: The movement pattern of the anterior teeth changed depending on the combination of lever arm height and anchor screw position. However, this pattern may be unpredictable in clinical settings because the movement direction is not always equal to the force direction.
키워드
Segmented palatal en-masse retraction; Finite element study; Anchor screw; Lever arm
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