To compare the stress distribution of residual posterior root restored with a new titanium alloy post of different diameter and taper, and discuss the rational design of posterior tooth post by the three-dimensional finite element method.

Mandibular second premolar image data was obtained by CBCT, and the mandibular second premolar post models with different diameter and taper were established with the help of Mimics data conversion, Geomagic Studio image processing technology and Creo/Parametric software. Then Abaqus was used to simulate the load condition of prosthesis and analyze the Von Mises stress of the cervical and apical regions.

With the same diameter, the influence of the different post tapers on the peak stress of the root cervical area was irregular. When the taper was the same, the peak stress of the root apex area decreased firstly and then increased as the diameter increased. When the diameter was 1 mm, the peak stress of the root cervical and apex area was the lowest.

The effect of diameter on the stress distribution of dentin is more important than that of taper. To select the reasonable diameter and taper of the post is helpful to reduce the peak stress of the root cervical and apex area.