The Three Dimensional Finite Element Analysis(3D-FEA) Of Stress Distribution On Post/dentin Interface Of The Tooth Restored With Post-core Crown At Different Angles

Objectives: To construct three dimensional element models of upper central incisor restored with different materials of post-core crowns at various angles and investigate stresses distribution on post/dentin interface of these models, and provide basis for the design of the patient with linguoclination or labioclination of upper central incisor in clinical.Methods:1 Thin-layer CT technique combined with AutoCAD and Ansys Workbench software were used to construct three dimensional finite element model G0°of upper central incisor restored with post-core crowns, dental crown long axis were inclined respectively lingual or labial side 10°,20°,30°to get models G_-10°,G_-20°,G_-30°,G_+10°,G_+20°,G_+30° of upper central incisor restored with post-core crowns at various angles.2 The stresses of model G0°with different post-core materials (casting Co-Cr alloy, Titanium alloy, Gold alloy) loaded 100N were calculated and analyzed using Analyses Workbench software based on the modulus of materials, The load including axial loading (along the longitudinal axis of dental crown on the incisor ridge) and oblique loading (at the angle of 40°to the longitudinal axis of dental crown on the palatine side of the incisor ridge third of crown).3 The stresses on post/dentin interface of upper central incisor restored with post-core crowns at various angles were analyzed using Anasys Workbench software, which undering axial and oblique loading of 100N.Results:1 The three dimensional element models (G₀°,G_-10°,G_-20°,G_-30°, G_+10°,G_+20°,G_+30°) of upper central incisor restored with post-core crowns at various angles were created.2 When the upper central incisor restored with different casting metal materials of post-core crowns , the peaks of stress located in the post/dentin interface at post apex, and the peaks were increased as the Elastic Modulus of the material increased. The two high stress regions are concentrated on the post/dentin interface of the coronal of the root and the apex of the post, and the stress concentration values of the interface decreased as the the Elastic Modulus of the material decrease.3 The changes of peaks stresses'when the upper central incisor restored with post-core crowns at various angles: (1) The crown inclined to the labial side: undering axial loading, the peaks of stresses on post/dentin interface increased as the angle increased, and the changes were opposite undering oblique loading. (2) The crown inclined to the lingual side: the peaks of stresses on post/dentin interface increased as the angle increased whether undering axial loading nor oblique loading.4 The changes of stresses'distribution when the upper central incisor restored with post-core crowns at various angles: (1) The crown inclined to the labial side: Undering axial loading, the two high stress regions are concentrated on the post/dentin interface of the coronal of the root and the apex of the post, and the stress concentration values of the interface increased as the angle increased. but the stress concentration values of the interface were opposite when undering oblique loading. (2) The crown inclined to the lingual side: Undering axial loading: the changes were same as the crown inclined to labial side. The stress concentration values of the interface increased as the angle increased.Conclusions:1 When the upper central incisor was restored with different casting metal materials of post-core crowns, The high stress regions are concentrated on the post/dentin interface of the vertical of the root and the apex of the post, and the stress concentration values of the interface decreased as the the Elastic Modulus of the material decrease.2 Whether dental crown long axis inclined to labial nor lingual side, undering axial loading, the stress concentration values of the interface increased as the angle increased.3 When dental crown long axis inclined to lingual side, the stress concentration values of the interface increased as the angle increased undering oblique loading. 4 When dental crown long axis inclined to labial side, the stress concentration values of the interface decreased as the angle increased undering oblique loading.5 When the post-core crown with angle was used in clinical, the crown inclined labially to restore linguoclination of upper central incisor are better than the crown inclined lingually to restore the labioclination, and choose the post-core material with lower Elastic Modulus.