Evaluating the effect of subcrestal placement on platform switched short dental implants and von mises stress in D3 bone-A 3D FEM study

Aim

To investigate the effect of platform switched short dental implants and subcrestal placement on von Mises stress in the maxillary anterior region (D3 bone) by using three-dimensional finite element model analyses (3D FEM).

Materials and Methods

Biomechanical behaviour of von Mises stress in maxillary anterior region (D3) bone were stimulated with the help of 3D FEM with the help of ANSYS WORKBENCH version 17.5. The bone model had a cortical core of (1 mm) surrounding the inner cancellous core, which represents D3 bone. Two models were designed model 1 (6 x 4.6 mm), (7.5 x 4.6 mm) and model 2 (6 x 5.8 mm), (7.5 x 5.8 mm). Loads of 100, 200 N were applied at an angle of 0°, 15°, 30° along the long axis of the tooth model.

Results

In all model's cortical bone exhibited greater stress than cancellous bone. Greater stress was reported in axial direction at 30° then 15° and least at 0° irrespective of load applied. An increase in implant length (7.5 mm) did not exhibit any stress reduction in both the model but implant diameter (5.8 mm) led to reduction in von Mises stress in both the groups. Greater the force applied greater was stress in both bones irrespective of direction of force applied (200N). Lastly subcrestal (0.5 mm) placement has slight reduction in stress compared to equicrestal placement in both the groups.

Conclusion

Numerical results from the current study suggest that, for short implants, implant diameter is considered more effective design parameter than implant length. Current findings state that platform switch short subcrestal implants results in conservation of marginal bone loss along with better stress distribution around peri-implant regions in D3 bone. However, all models analyzed in this study showed development of von Mesies stresses within physiological limits for human cortical bone.

Biomechanical Evaluation of Stress Distribution in Subcrestal Placed Platform-switched Short Dental Implants in D4 Bone: In Vitro Finiteelement Model Study

The present study was carried out to assess stress distribution in the maxillary posterior bone region (D4 bone) with the help of a short platform switched subcrestal dental implants using the FEM model. Missing teeth surfaces related to the maxillary posterior region were stimulated. The bone model had a cancellous core of (0.5 mm) which represents D4 bone. A 7.5x4.6 mm screw type implant system with 3.5 platform switch abutment was selected. ANSYS WORKBENCH was used to model all the finite element structures. Force of 100 N was tested and adapted at an angle of 0º, 15º, 30º on the tooth model. Overall results from the current study showed that a high amount of stress was seen in cortical than in relation to cancellous bone. Stress values reduced from equicrestal to subcrestal (2 mm) placement of dental implants irrespective of angulation of load from 0o to 30o in both types of bone. However higher stress values were seen when force was applied in an oblique direction (30o) in comparison to a vertical load (0o). Least amount of stress was noticed when platform switched implants were placed 0.5 mm subcrestatlly irrespective of angulations of a load. Platform switched short subcrestal implants reduced the stress in the D4 cortical bone than in contrary equicrestal implant placement. This results in the preservation of marginal bone leading to implant success.