[Establishment of the three-dimensional finite element model of the first permanent mandibular molar and its stress analysis].

Objective: To establish more rational three dimensional finite element model (FEM) of the first permanent mandibular molar and to study the internal stress distribution.

Methods: The FEM was applied to analyze the stress distribution of the first permanent mandibular molar under various loading conditions.

Results: Under all five loading conditions, the maximum von-Mises stress and compressive stress in enamel were larger than that in dentin, and the tensile stress in enamel was smaller than that in dentin. When vertical force and buccal-lingual oblique force were loaded, the stresses in the enamel and dentin were minimum; when lingual-buccal oblique force was loaded, the stresses were maximum; the stresses were mainly distributed at cervical region, furcation and apical area of the mesial-lingual root canal wall.

Conclusions: The stress value changes and stress distribution in the enamel and dentin were closely related with the direction of the occlusion force.