Investigation of the effect of using sloped implant design on stressgenerated by finite element analysis in the all-on-four treatment concept

The aim of this study is to examine the stresses that will occur on the implant, prosthetic framework, peri-implant bone, abutment and abutment screw with the use of an angled implant neck design that ends at the same level with the bone in posteriorly angled implants, in comparison with systems using the standard implant neck design. In our study, due to the amount of atrophy, all-on-four treatment concept will be applied and mandible and maxilla models created. Implant placement and positioning in the excessively resorbed maxilla and mandible is often difficult. Therefore, in edentulous jaws, inclination of distal implants has been suggested to rule out graft application in excessively resorbed ridges and to provide a more predictable implantation protocol. All-on-four treatment concept in the mandible and maxilla in the anterior region, 2 implants 3.8x11 mm in size (Quattrocone, Medentika) inserted in vertical position. In the posterior region, 30-degree angled 4.3x11 mm implant (Quattrocone30, Medentika) inserted and simulated by placing it inside the bones. At this stage, two different models will be obtained by using 30 degree angled implant neck and standard implant neck models for implants placed in the posterior region. For both scenarios, loadings were applied to each tooth from the right side of the model over the 6th teeth, at an angle of 30 degrees, from the buccal tubercle of the 250 N teeth, from the lingual to the palatal and buccal direction. After the simulation, the stress values in the cortical bone around the implants, abutments, abutment screws, prosthetic framework and implant neck and the amount of displacement in the prosthetic restorations will be determined. While the Von Misses value was found to be 94.9 MPa in the implant with an sloped neck region in the posterior region of the maxilla, the Von Misses value was found as 117 MPa in the implant with a flat neck region. While the Von Misses value was found to be 174.4 MPa in the implant with an sloped neck region in the posterior region of the mandible, the Von Mises value was found as 328.9 MPa in the implant with a flat neck region. The Von Mises stress in the neck region was higher in the straight implant than in the sloped implant. In all models, the maximum Von Mises stress on the implant and abutment occurred on the implant and abutment on the side of the load. It was observed that the maximum and minimum principal stress values were higher in the bone region around the flat implant. Keywords: Peri-implant bone, all-on-four, dental implant