Effect of the Number of Dental Implant Neck Threads in Contact With the Cortical Bone on Interface Stresses Using Finite Element Method

Dental implants are a valuable, safe and predictable solution for patients suffering from tooth loss. The implant shape plays a great role in the success of dental implant, due to its effect on stress distribution in the surrounding bones. Therefore, optimizing some of implant shape parameters may improve stress distribution and consequently may lead to an increase in implant success rate. In this study, the 3D finite element analysis is used to investigate the influence of the number of threads in the neck of the implant on the implant-cortical bone interface stresses. The stress distribution along the implant-bone interface and their displacements were determined using ABAQUS/CAE 6.10 software. Overall, the stress was highest in the cortical bone at the neck of implant and lowest in the cancellous bone regardless of the number of threads in contact with cortical bone. On the other hand, reducing the number of threads in the neck resulted in a decrease in the developed stresses in both types of bones. The developed stresses around the bones decreased gradually in cortical bones and dramatically in cancellous bones when the number of threads decreased in the neck of implant. The stress reduction between the smooth neck to the fully threaded neck decreased the developed stresses by 24% in the cortical bone. However, due to improve the implant osseointegration, it is recommended to keep one or two threads in the cortical bone.