Evaluation of Mechanical Stress Analysis around Tilted Implantations by 3D-FEA

Objectives: The volume of maxillary and/or mandibular bone limits dental implantations. In this study, the tilted implant design was evaluated for the scarce maxillary bone. The aim was to estimate the mechanical capacity of the inclined implantations by three-dimensional finite element analysis (FEA). Methods: The X-ray CTs of maxillary bone were taken for assemble FEA models. The control was set vertically from the alveolar ridge toward the maxillary sinus wall as the conventional implantation. The test design (TD) was set in a tilted way, from the distal portion of the second molar to the mesial portion of the apex of the first molar root. TD had the larger inclined angle than the control. The compulsory displacement (2mm) was applied vertically/horizontally to the head of FEA models. Results: The control was 6.95mm long and TD was 8.36mm long in the maxillary bone which shows TD was 120% longer than the control. There was a significant difference (t-test, p<0.05) between the length of implantations. The control showed that the stress distribution (Max=1GPa) existed around the apex of the implant in the sponge bone and at the cortical bone surrounding the implant neck with vertical/horizontal load. On the other hand TD showed that the larger stress distribution (Max=5GPa) existed in the buccal/palatal cortical bone surrounding the neck of the implant and the maxillary sinus palatal wall. The portion of stress distribution showed significant difference between the control and TD. The stress distribution of the control reflected the load directory. However, TD dispersed the load into the cortical and the sponge bone. Conclusion: In the case of the implantation in scarce bone mass, the tilted implant design was better ,as it disperses the large stress, in supporting and resisting the load based on the disperse of the large stress than the conventional vertical implantation.