Rotation axis of the maxillary molar and maximum tooth movement according to force direction

Abstract

Aim: To evaluate the correlation between the maxillary molar rotation center and the direction of the maximum tooth movement according to the force direction using three-dimensional finite element analysis (3D-FEA). Methods: Computed tomography of a human tooth was used to build a finite element model, which comprised the cancellous and cortical bones, the periodontal ligament and the tooth. After applying lateral and posterior boundary conditions, a 1 N force was applied to the mesial and lingual faces of the maxillary molar to simulate buccal and distal tipping forces on the tooth. Results: The initial displacement of the maxillary first molar was greater for distal tipping than for buccal tipping. The rotation axis for distal tipping in this simulation was located on the furcation of the first molar. For buccal tipping this axis was on the cervical and middle third of the buccal roots of the maxillary first molar. Conclusions: The applied movement interferes in molars Cres location. Higher molar tipping is expected when distal movement is applied rather than buccal movement thanks to the close distance between Cres and location of the force applied to this movement.

Three-dimensional nonlinear prediction of tooth movement from the force system and root morphology

“…The current method to describe the type of tooth movement consists of measuring the distance from the tooth's projected axis of rotation (center of rotation; C ROT ) to the virtual intersection of the axes of resistance (center of resistance; C RES ). Some recent studies [1][2][3][4] and many previous studies [5][6][7][8][9] investigated the role of M:F associated with different tooth movements. One classic study focused on applying a force perpendicular to a canine long axis with a parabolic shaped root, obtaining the Burstone formula (M:F ¼ 0.068 3 h 2 /y), where h is the distance from the alveolar crest to the apex and y is the distance between the C RES and the C ROT .…”