Objective:To study the prosthodontic design for the treatment of maxillary first molar mesio-lingual cusp defect with subfis-sue.Methods:A finite element model of maxillary first model,including mesio-lingual cusp defect with subfissue,periodontal support-ing tissue and a section of the maxilla was established by cone beam CT.Different prosthodontic designs for respective restoration and simulating different bite force were adopted,the Von Mises stress,maximum compressive stress and the crack distribution,J integral and the root displacement were analysed.Results:In the metal pile restoration model,the stress,JINT value and the equivalent stress and displacement of root were the smallest.With the increase of crack depth of the vertical and oblique fissue,the equivalent levels of stress (equivalent stress of J integral),the stress experienced by the dentin along with the peak of the maximum principal,increased signifi-cantly.Under 4 kinds of force direction and 3 repair methods,the equivalent stress peak value,J integral dentin stress,maximum prin-cipal stress peak value and dentin stress peak value of the cracks was 200 N,90°>200 N,45°>600 N,0°>200 N.Conclusion:High elastic modulus and all ceramic crown may lead to minimal equivalent stress,J integral,dentin equivalent stress and maximum principal stress.When subfissure is repaired,teeth fracture remains possible and any possible propagation may exist.The effect of later-al force on the crack and the dentin is greater than that of vertical force for crack expansion and tooth fracture.

Objective:To investigate the molecular mechanism of the disease based on the clinical characterization and genetic mutation analysis in a family with intellectual disability.Methods:The proband with intellectual disability was diagnosed at Luohe Central Hospital in December 2019. Peripheral blood samples were collected from four family members. Whole exome sequencing (WES) was used to screen the pathological mutations. Then the PCR and Sanger sequencing were used to verify the selected mutations and combine the relevant database to analyze variation loci.Results:We infer that the ARX c.1162 A>G was co-segregated with the phenotype of the family based on the results of WES. The results of sanger sequencing and WES are consistent. The mother of the proband is the carrier of the mutation. There is no mutation frequency reported in the healthy population. The mutation of the ARX c.1162A>G is harmful inferred by a variety of bioinformatics software. Combined with the phenotypic analysis of OMIM database, we infer the phenotype caused by the mutation is consistent with the patients in the family.Conclusion:The mutation of the ARX c.1162 A>G may be the cause of the intellectual disability in the family affected. And the variant has not been reported in China.