Comparison Of The Flexural Strength Of Premolars With Different MO Defects After Inlay And Full Crown Restoration

Objects: To compare the flexural resistance of full crown restoration and inlay restoration in different residual tooth tissues of maxillary premolars by in vitro experiments,and provide a clinical basis for oral prosthetics to select suitable restorations.Methods: Select 40 maxillary premolars that were pulled out due to orthodontics.After the root canal is prepared with stainless steel protaper to F1,and fill it with cold gutta-percha lateral condensation.Use a flowing resin pad at the bottom of dental pulp cavity.The experimental teeth were then divided into A,B,C,D four groups.When the group A and group C are MO-type defects and the defect area is 3 mm,the isolated teeth are repaired with metal crown and metal inlay respectively.The isolated teeth were repaired with metal full crown and metal inlay when the B group and the D group were MO type defects respectively and the defect area was 5 mm.Perform static loading on all experimental teeth Loading the head and the tooth surface vertically at 1mm/s until the teeth are broken with an electronic universal testing machine,and record the instantaneous force value when the specimen is destroyed.One-way ANOVA and chi-square test were performed on the results using SPSS21.0 software.Results: Fracture resistance: Group A,group B > group C > group D,there was no significant difference between groups A and B.In the case of two kinds of defect areas,the fracture resistance of the metal full crown repair is greater than that of the metal inlay restoration,and the metal inlay of the defect area of 3 mm has a fracture resistance greater than that of the metal inlay with a defect area of 5 mm.Conclusion: According to the results of the analysis of the experimental data,in the clinical work,when the defect area of the maxillary premolar MO type defect is 5 mm,the metal crown has higher bending resistance.When the defect area of the maxillary premolar MO type defect is 3 mm,the metal full crown still has higher fracture resistance,but the fracture resistance of the metal inlay is enough to reach the normal use level in the mouth,so according to the principle of minimally invasive,metal inlays are a more suitable repair solution.