Objective:To compare influence the residual dentin stress of posterior teeth post-core different materials with or without porcelain fused metal crown (PFM)

in order to instruct clinically rational choice of materials. Method:Models were created by abrasive methnd which piclures were acqiured with digital camera. Three-dimensional models of maxillary first molar short in medial palatal cusp were constructed and restored with of different materials post-core on condition of having or not having PFM. Then the magnitude and distribution of model residual dentin stress were analyzed by the three-dimension finite element analysis. Result:1 When maxillaU first molar which is short in medial palatal cusp was restored with post-core and porcelain fused mental crown

its peak value of stress was evidently less than that with post-core but without porcelain fused mental crown

meanwhile

they had different stress distribution. 2 When maxillary first molar which is short in medial palatal cusp was restored with post-core and porcelain fused mental crown

post-core of different materials had little influence on peak value of stress of residual dentin

but post-core of high elasticity modulus change normal dentin stress distribution

while post-core of low elasticity modulus did not. Conclusion:On the condition of normal occlusal force

PFM is extremely important to protect no-vital tooth

which is crucial for successful post-core crown. Meanwhile

post-core of different materials show little difference in fracturing rate of tooth restored with post-core and porcelain fused menial crown

and the fracture namely happen.