Effect of Marginal Bone Resorption on Stress Distribution in Implants of Different Lengths: A Three-Dimensional Finite Element Analysis

Aim: Marginal bone resorption occurring around dental implants may cause biomechanical changes and lead to implant loss over time. It is not fully understood how this bone loss affects implants of different lengths and the stress on the surrounding bone. Material and Method: Implant models with lengths of 6.6 mm and 13 mm were created at five different marginal bone resorption levels (0, 1, 2, 3 and 4 mm). All implants were 4.6 mm in diameter and were placed in idealized bone blocks with a crown representing the maxillary first molar. The models were analyzed under vertical and 30° oblique load of 100 newton (N). Von Mises stress in the implant body and maximum and minimum principal stress in cortical and cancellous bone were evaluated. Results: The highest stress values were observed in 6.6 mm implants under oblique loading. While the von Mises stress was 97.4 megapascals (MPa) at 0 mm bone loss, it increased to 133.0 MPa at 4 mm bone loss. These values increased from 82 MPa to 99.1 MPa in 13 mm implants. The maximum principal stress in cortical bone increased from 13.7 MPa to 62.5 MPa in short implants and from 11.8 MPa to 36.0 MPa in long implants. Stress values were found to be higher in short implants at all resorption levels. Conclusion: Implant length and level of bone loss affect stress distribution. Short implants and advanced resorption create more stress, while stress can be temporarily reduced by changing the load transmission geometry in the early stage.