Influence of cuspal inclination on the stress distribution in maxillary first molar / 实用口腔医学杂志

ABSTRACT

Objective:To evaluate the bio-mechanics of the cracked molars. Methods: A three dimensional finite element(3D-FEM) model of an upper first molar was constructed by Ansys 8.0 software. The model's cuspal inclination was shaped according to the mean value of the cuspal inclination in the cracked maxillary first molars and the intact ones respectively. The influence of cuspal inclination on the stress distribution was evaluated under different loads:Load of 600 N vertically applied to the occlusal surface of the model, or load of 200 N applied from three directions (vertically, at a 45?angle, horizontally). Results:For the model with the cuspal inclination of the cracked maxillary first molars, its maximum tensile stress, compressive stress and Von Mises stress were higher than those of the control models. The tensile stress and Von Mises stress increased with the increase of force direction and became to the highest under horizontal loads. The tensile stress was mainly distributed at the mediolingual cusp, centre groove and the palatal side of the cervical region. Conclusions: Under equivalent loads, the molar with bigger cuspal inclination suffers more unfavorable stress, which will magnify the occurrence of cracked tooth syndrome (CTS), and horizontal bite force may be a critical factor.