[Analysis the effect on the stress of wall of root canal by different proportion between crown and root].
OBJECTIVE
Use FEM to observe the relationship between the change of alveolar ridge's height and the stress change of wall of root canal.


METHODS
Modify the model on the basis of the set up model of the mandibular first molar, simulating the height of alveolar ridge and reducing 1/4, 1/3, 1/2 of the height to set up modified model, and load on the modified model by vertical and lateral forces. Then calculate the maximum mises stress of each part of teeth and wall of root canal.


RESULTS
The stress-changing tendency of each part of wall was similar to the changing tendency of each part of teeth, but the stress of wall was fewer than the stress of teeth. The stress value of original model was close to the modified model at the orifice. Then the stress of original model obviously reduced, and the stress of the modified model reached maximum in the coronal thirds, and when the fixed height was lower, the stress was larger, the stress reduced more slowly. The lateral stress was larger than the vertical stress, and when the fixed height was lower, the difference was more obvious.


CONCLUSIONS
The change of alveolar ridge's height will affect the stress change of wall of root canal, and which is in an inverse proportion.
Department of Oral Medicine, Ninth People's Hospital, Shanghai Second Medical University, Shanghai 200011, China. hj1221@online.sh.cn
Jin
J
Hong
Wen-wei
WW
Xia
Huan-guo
HG
Xiong