Three-dimensional Finite Element Analysis Of Wedge-shaped Defect Of Mandibular First Premolar Restored With Different Materials

Obejective:To analysis the stress of wedge-shaped defect of the first mandibular premolars,the wedge-shaped defect was restored with different materials by establishing the 3D finite element model.Materials and Methods:A 3D finite element model was established by scanning the first premolar of the mandible with CBCT.Two groups of wedge-shaped defects with different shapes were designed.The unrestored wedge-shaped defect model was used as the control group,and four experimental groups were set up according to different materials to re wedge-shaped defect: Vita Enamic group(A),Lava Ultimate group(B),IPS e.ax CAD group(C),and Z350 composite resin group(D).The models were loaded vertically and obliquely 45°respectively,and the Von Mises stress in the restorative material was calculated.Results:1.After the wedge-shaped defect was restored,the stress distribution changed.The Von Mises stress distribution nephogram shows that before the restoration of the wedge-shaped defect,the Von Mises stress distribution was mainly concentrated at the tip of the defect and the axial angle of the pulp wall.When wedge-shaped defects are restored,the Von Mises stress is concentrated on the outer edge of the restoration.2.When oblique loading was performed under the same wedge-shaped defect morphology,the Von Mises stress generated by each group of models must be greater than the vertical loading.3.Under the same conditions,the Von Mises stress of the four materials in the experimental group were less than the Von Mises stress of dentin at the wedge-shaped defect of the control group.In the four groups of models,the peak value of Von Mises stress in group A(Vita enamic),B(Lava Ultimate),and D(Z350 composite resin)were significantly reduced.The Von Mises stress value of B was the smallest and the decrease was the largest.The group C model had the highest peak Von Mises stress and the smallest reduction.Conclusion:1.The Von Mises stress of the wedge-shaped defect was effectively reduced by resin-matrix ceramic inlay.2.While planing to restore the wedge-shaped defects,the lateral force on the teeth of the wedge-shaped defect should be minimized.