Does a sloped neck implant design facilitate All-on-4 surgeries? A three-dimensional finite element analysis

Aim: In the treatment of edentulous resorbed mandibles using All-on-4 concept, the distal part of posteriorly tilted implants with a conventional flat neck design is usually embedded in the bone, which may lead to improper installation or positioning of angled multiunit abutments. Bone trimming from the distal area, where the implant neck is embedded in the bone, is typically necessary to avoid this complication. This study aimed to evaluate the biomechanical behavior of a sloped marginal neck configuration of implant posteriorly tilted at 30° in edentulous mandibles using a three-dimensional finite element analysis (FEA). Methodology: The sloped neck implants were posteriorly tilted at 30° without any further operation in the edentulous mandibular model designed using the FEA. The tilted conventional flat neck implants were placed at the same length, diameter, and angle, and 2 mm2 of bone was trimmed from the distal area. Similar multiunit abutments, two conventional flat neck implants axially placed on the anterior side, titanium frameworks, and acrylic resin prosthetic dentures were created for both models. The biomechanical behaviors of the models were evaluated by applying a foodstuff force of 50 N to the incisors, 100 N to the premolars, and 150 N to the molar cantilever. Results: The von Mises stress value of the sloped neck implants (158.489 MPa) was lower than that of the conventional flat neck implants (177.208 MPa). Both the maximum and minimum principal stress values ​​in the surrounding cortical and cancellous bones were within the acceptable physiological limits. Conclusion: Sloped neck implants can be placed easily and are less invasive than conventional flat neck implants; thus, they can be a treatment alternative that can facilitate the All-on-4 concept.   How to cite this article: Toprak ME. Does a sloped neck implant design facilitate All-on-4 surgeries? A three-dimensional finite element analysis. J Med Dent Invest 2023;4:e230310. https://doi.org/10.5577/jomdi.e230310   Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.