Three-dimensional finite element analysis of distal proximal occlusal defect of short crown molar restored with endocrown / 中国组织工程研究

ABSTRACT

BACKGROUND:For teeth with normal dental crown height,pulp cavity retention crown restoration with different depths of the pulp cavity and different repair materials affects the stress and flexural strength of tooth tissue.For short crown molar defects,the research on pulp cavity repair mainly focuses on clinical observation and in vitro flexural strength experiments. OBJECTIVE:To establish a three-dimensional finite element model for short crown molar restored by the endocrown after root canal treatment to analyze the effects of different pulp cavity retention depths and different repair materials on the distribution and size of dentin equivalent stress. METHODS:Based on establishing the complete model of the short crown mandible first molar,a three-dimensional finite element model was established for repairing the distal adjacent defect of the short crown molar with different pulp cavity retention depths(h=2,3,4 mm)and different repair materials(zirconia,lithium disilicate).Under the oblique loading,the equivalent stress distribution was observed.The peak value of dentin equivalent stress and the mean value of equivalent stress near the bottom of the mesial pulp cavity wall were calculated. RESULTS AND CONCLUSION:(1)Equivalent stress concentration areasThe stress of complete short crown molar and restored models mainly concentrated in the mesial root mesial neck and mesial root lingual neck.The stress concentration area was found in the mesial pulp cavity wall corresponding to the bottom layer of restored models,and the stress concentration was obvious in the 4 mm retention depth group.(2)Under the same repair material,the peak value of dentin equivalent stress was the lowest at 3 mm for all models after repair.The average value of equivalent stress near the bottom of the mesial pulp cavity wall was lowest at 3 mm.(3)Under the same retention depth,there was no significant difference between the two materials in the dentin equivalent stress peak and the mean value near the bottom of the mesial pulp cavity.(4)The results showed that under the conditions of this experiment,the endocrown was used to repair the defect of the short crown molar and the retention depth was 3 mm,which was more beneficial to protect the remaining dental tissue.The selection of zirconia or lithium disilicate as the repair material had little effect on the dentin stress.