Biomechanics and Peri-implantitis: The Effect of a Subcrestal Wing-Thread to Decrease Alveolar Crestal Bone Strain. Theory, Finite Element Analysis, and Clinical Application

Purpose: This study used finite element analysis and a clinical case example to test the hypothesis that a wing-thread placed 4 mm below the top of an implant would decrease crestal bone loss in function. Materials and Methods: Finite element analysis was used to compare standard and wingthread implants subjected to axial and off-axis forces based on the hypothesis that decreasing bone strain at the alveolar crestal margin improves peri-implant bone stability. A clinical case example of the wing-thread implant was followed for 30 months. Results: Stress concentration was diminished at the crest when a wing-thread was used compared to a standard implant body. Ninety-degree lateral forces were diminished by a factor of 10 in the wing-thread implant. A patient followed for 30 months showed stable bone levels around the wing-thread implants. Conclusion: The wing-thread hypothesis appears to have some support for increasing bone stability based on finite element analysis and early clinical results. Keywords: biomechanics, bone loss, bone strain, mechanostat, peri-implantitis, wing-thread