The effect of microthread design on magnitude and distribution of stresses in bone: A three‑dimensional finite element analysis

Shima Golmohammadi, Amir Eskandari, Mohammad Reza Movahhedy, Adileh Shirmohammadi, Reza Amid


Background: The researches regarding the influence of microthread design variables on the stress
distribution in bone and a biomechanically optimal design for implant neck are limited. The aim of
the present study is to compare the effect of different microthread designs on crestal bone stress.
Materials and Methods: Six implant models were constructed for three‑dimensional finite element
analysis including two thread profile (coarse and fine) with three different lengths of microthreaded
neck (1 mm, 2 mm, and 3 mm). A load of 200 N was applied in two angulations (0° and 30°) relative
to the long axis of the implant and the resultant maximum von Mises equivalent (EQV), compressive,
tensile, and shear stresses were measured.
Results: Regardless of loading angle, the highest EQV stress was concentrated in the cortical
bone around the implant model using a 1 mm neck of fine microthreads. Under axial loading,
there was a negative correlation between the length of the microthreaded neck and stress level
in both profiles. However, the same pattern was not observed for coarse microthreads under
oblique loads. All types of measured stresses in all constructed models were increased with
oblique loading.
Conclusion: Peak stress levels in implant models varied with microthread profile and direction of
loading. The microthread profile seemed more important than the length of the neck in reducing
loading stresses exerted on the surrounding bone. Fine microthreads on a 3 mm implant neck
showed consistently higher cortical bone stress than other models.
Key Words: Bone, dental implant‑abutment design, finite element analysis, mechanical, stress

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