Evaluation of Stress Induced by Telescopic Double Crown Retained Dentures

Objective: The aim of the study was to investigate the influence of preparation angle of the abutment teeth on stress magnitude and distribution in the telescopic double crowns and denture frameworks during functions. Methods: Experimental 3D models of the teeth structures and combined dentures were achieved. The models of the mandibular canines were obtained by 3D modeling, using literature data. Crown preparation shapes with different angles (from 0 to 10 degree) were modeled, to allow the design of the inner cast metallic crown. The inner crowns were covered by the outer crowns, which were connected to the denture framework. The finite element models were obtained by importing the solid models into finite element analysis software. All the nodes on the external surface of the root were constrained in all directions. A displacement between 0.5 and 1 mm was applied on the distal end of the removable framework, to simulate the displacement toward the ridge during functions. Von Misses equivalent stresses were calculated in the remaining teeth structures, double crowns and removable framework in condition of varying preparation angles and displacements. Results: The maximal equivalent stress values were not significantly different for the investigated preparation angles. Only the distribution of the stresses depends on them, stress areas increase with the increase of the angle. Stresses are located under the preparation line of the teeth, in the cervical part of the inner crowns, and distal the outer crowns in the removable framework. Stresses increased with the displacement in all components, maximal values became double with the increase of the displacement from 0.5 to 1 mm. Conclusion: According to the results of this study, the effect of the preparation angle is not important for the stress values, but the displacement of the denture during function may increase stresses. (Grant ID_1264)