Three-dimensional finite element analysis on the stress of mandibular first molar restored with different locations and numbers of gold alloy posts and cores / 中国组织工程研究

ABSTRACT

BACKGROUND:The design of post and core of the molar is affected by various factors,including the effect of the number of posts on the retention force and the effect of the number of posts on the dentin stress and distribution.OBJECTIVE:To make a mechanical analysis on the three-dimensional finite element models of the mandibular first molar defect restored with different numbers and locations of gold alloy posts,cores and all-ceramic crown.METHODS:Cone-beam CT based three-dimensional finite element models of post and core restored first mandibular molars were established,with seven different post designs.According to the numbers and location of gold alloy post inserted into root canal,a single post was placed at the mesial buccal root in group A,a single post at the mesial tongue root in group B,a single post at the distal root in group C,two posts at the mesial buccal root and the distal root in group D,two posts at the mesial buccal root and mesial tongue root in group E,two posts at the mesial tongue root and the distal root in group F,one post respectively at the mesial buccal root,mesial tongue root and distal root in group G.The von Mises criterion was applied for comparing the maximum yon Mises stress value of dentin and stress concentration areas in the seven models which restored with golden alloy posts and cores with all-ceramic crown under the maximum (600 N),vertical (225 N),inclined (225 N) and horizontal (225 N) loads.RESULTS AND CONCLUSION:Under vertical,inclined and horizontal direct loads,the maximum stresses on the remaining dentin in group C were significantly lowest,compared with the groups A and B.The maximum stresses on the remaining dentin changed irregularly with the variation of the numbers and location of posts,when the mandibular first molar defect was restored with all-ceramic crown with gold alloy posts and cores.Under the horizontal load,the maximum Von Mises stress value of the dentin increased remarkably.Under the horizontal load,the maximum stresses on the remaining dentin in group E were the highest.To conclude,the numbers and location of posts and cores have influence on magnitude and distribution of stress,when the mandibular first molar defect is restored with all-ceramic crown with gold alloy post and core.