Korean J Orthod.  1989 Mar;19(1):45-60.

A finite element analysis of the displacement and stress distribution of human dry mandible during the mandibular first molar cervical traction

• Ahn EY
• Chung KR

Abstract

This study was undertaken to analyze the displacement and stress distribution in the mandible according to the pulling directions during mandibular first molar cervical traction after mandibular second molar extraction. The 3-dimensional finite element method(FEM) was used for a mathematical model composed of 594 elements and 1019 nodes. An orthodontic force, 450gm, was applied to the each mandibular first molar in parallel, and below the occlusal plane by 7degrees and 25degrees and meet the midsagittal plane by 40degrees toward posterior direction. The results were as follows: 1. Mandibular teeth were displaced in more downward, posterior and lateral direction. Especially high stress was noted in case of parallel pull than in case of below the occlusal plane by 7degrees and 25degrees. 2. Mandibular first molar was moved bodily. 3. Generally, alveolar bone, mandibular body, ascending ramus and mandibular angle portion were displaced in downward, posterior and lateral direction. But coronoid process was displaced in downward, forward and lateral direction, and anterior and inner middle portion of condyle head and neck were displaced in downward, forward and medial direction, and posterior and outer middle portion of condyle head and neck were displaced in upward, forward and medial direction. 4. Maximum stress was observed at the condyle head and neck portion. With steeper direction of force, condyle head and neck showed more stress than parallel relation to the occlusal plane.

MeSH Terms

Dental Occlusion
Finite Element Analysis*
Head
Humans*
Mandible*
Models, Theoretical
Molar*
Neck
Tooth
Traction*