Analysis of the Effect of Thread Depth in Four Different Thread Designs on the Stress Distribution at the Implant-bone Interface Using Finite Element Analysis – A Comparative Three-Dimensional In vitro Study

Abstract

Statement of Problem: Treatment with dental implants owes much of its success to the development and maintenance of an osseointegrated bone-implant interface. The development of this interface is influenced by various factors, of which implant thread design plays a dominant role. Purpose: The purpose of this study is to analyze the effect of thread depth in four different thread designs on the stress distribution at the implant-bone interface using three-dimensional finite element analysis. Materials and Methods: Four implant models with different thread shapes, namely V thread, square thread, buttress thread, and reverse buttress thread with an uniform thread depth of 0.4 mm were designed. These models were then placed in the mandibular first molar region. Force of 100 N was applied axially and at 45°angle to the implant. Von Mises stress was measured at the implant – Bone interface area and compared for the different designs. Results: The color plots obtained were studied and the maximum Von Mises stress was noted and tabulated for each condition. Stress distribution in the finite element models comes in the numerical values and in color coding. Maximum values of Von Mises stress are denoted by red color and minimum value by blue color. In between, the values are represented by bluish green, green, greenish yellow, and yellowish red in the ascending order of stress distribution. Conclusion: Thread design plays an important role in stress distribution in implant and bone. Varying Von Mises stress is seen at the cortical bone-implant and cancellous bone-implant interface. Clinical Implication: Successful osseointegration is necessary for implant success and thread design plays a very important role in osseointegration. Therefore, the selection of implants with proper thread design contributes greatly to the success of an implant-retained prosthesis.

Keywords

• cortical bone
• implant
• von mises stress