Comparison of Short and Standard Implants in the Posterior Mandible: A 3D Analysis Using Finite Element Method.

Objectives: This study aimed to analyze functional stresses around short and long implant-supported prostheses with different crown heights.

Materials and Methods: Four three-dimensional (3D) models were designed with SolidWorks 2015. In models 1 (control) and 2, three dental implants (second premolar 4.1×8 mm, molars: 4.8×8 mm) were placed. In models 3 and 4, three dental implants (second premolar 4.1×4 mm, molars: 4.8×4) were placed. Residual bone height was 10 mm in groups 1 and 2 (grafted bone) models and 6 mm in groups 3 and 4. The crown heights were modeled at 11.5 mm for groups 1 to 3, and 15 mm for group 4. The applied oblique force was 220 N to simulate chewing movements. The maximum von Mises and principal stresses on the implants and the supporting tissues were compared using the 3D finite element method.

Results: In all models, the highest stress value was seen within the most coronal part of bone (crestal bone), which was cortical or grafted bone. The highest stress values in the bone supporting the implant neck were seen in the premolar region of each model, especially in model 4 (291.16 MPa). The lowest stress values were demonstrated in the molar region of model 3 (48.066 MPa). The model 2 implants showed the highest von Mises stress concentrated at their neck (424.44 MPa).

Conclusions: In atrophic posterior mandible with increased crown height space, short implants with wider diameter seem to be a more feasible approach compared to grafting methods.