The Effect of Microthread Design on Magnitude and Distribution Pattern of Stress and Strain in Peri-implant Bone

Abstract

The aim of the present study is to compare the effect of different microthread designs on magnitude and distribution of stress and strain in bone around dental implant. Methods: Six implant models were constructed for 3D FEA including two thread profiles (coarse and fine) with three different lengths of microthreaded neck (1 mm, 2 mm and 3 mm). A static load of 200 N was applied in two angulations (0 and 30) relative to the long axis of the implant and the resultant equivalent (EQV) and maximum compressive, tensile and shear stresses and strains were measured. The stress and strain contours in both cortical and cancellous bone were also obtained. Results: Regardless of loading angle, the highest EQV stress was concentrated in 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 and the model with a 2 mm neck showed the highest stress. All types of measured stresses in all constructed models were increased with oblique loading. Moreover, the deformation in the cancellous bone was generally more than the cortical bone. 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, since the coarse profile performed more favorably than the fine microthreads. Fine microthreads on a 3 mm implant neck showed consistently higher cortical bone stress than other models.