A Dynamic Finite Element Analysis Of Stress Distribution In The Supporting Bone Of Mandibular Cantilever Fixed Bridge Abutment

ObjectiveIn this study, a three-dimensional model was generated to analysis the stresses induced in the supporting bone tissue of the FPD abutment in the mandible under transient dynamic loads, so as to provide the oretical references of bio mechanics for clinical application of FPD.MethodsThe finite element model of the mandible molar FPD was reconstructed using CT images, AutoCAD and ANSYS software, which included (?). Finite element analysis was performed on the model under dynamic loads in various directions and positions in a masticating cycle. The stress and stress-time curves were analyzed to study the biomechanical behavior of supporting bone of abutments.Results1 The constructed model has a good similarity to the morphology of the 3-D images, which can serve for the needs of the three-dimensional stress analysis.2 The stress at the neck of cortical bone for(?) was most concentrated under vertical loads. Under oblique loads, the stress concentration is at the neck of cortical bone, root furcation and root apex.3 Loading onf(?) without bridge, the maximum Von Mises value of the cortical bone around (?) was 47.415Mpa after lingual loading,1.3 times that around(?) before restoration. In bridge, the cortical bone value around(?) was 31.403Mpa,0.7times that around(?). The stress diffuses around the supporting bone.4 When loading on(?), before restoration, under oblique loads, the maximum VonMises value of the cortical bone around (?)-was 36.878Mpa,1.9 times that under vertical loads, while the value of the cancellous bone was 15.706Mpa,2.9 times that under vertical loads. After restoration lading on (?), under oblique loads, the maximum VonMises value of the cortical bone around (?) was 76.878Mpa,1.4 times that under vertical loads,while the value of the cancellous bone was 18.298Mpa,2.3times that under vertical loads. Oblique loads tend to produce more stress concentration. The stress was more even-distributed after restoration.5 After fixed cantilever bridge, loading at (?), the peak stress value of(?) is 48.548Mpa, while (?)'s peak sterss value is 77.676Mpa. They are all sub mandible threshold.6 Before prosthodontics, the supporting bone of the abutments is mainly under compressive stress, while those of (?) display more tensile stress after restoration under loading on 1567, especially at cervical margin near the pontic.7 In a cycles, there is various residual stress in different alveolar bone. The residual stress on the spongy bone is 0.23Mpa, while the residual stress on the cortical bone for (?) is 3Mpa.Conclusions1 The method of combining CT and AutoCAD,ANSYS software to construct a 3-D finite element model is feasible and effective. Procedure of building models is available to improve model similarity and efficiency.2 The stress in the neck of cortical bone was most concentrated. oblique loads tend to produce more stress concentration.3 Thanks to the bridge, the stress of supporting bone was more even-distributed. The stress on the abutment nearest to the pontic was highest.4 The stress diffuses around the supporting bone to increase the tolerance of unit area as loading was applied in the cantilever bridge, and the peak stresse values are all sub mandible threshold.5 After a masticating cycle, there is various residual stress in different supporting bone depending on damping.