Stress Distribution Characteristics of Various Implant Systems due to Non-Central Occlusal Loads

Stress Distribution Characteristics of Various Implant Systems due to Non-Central Occlusal Loads
2003
By: Bozkaya, Din??er+; M??ft??, Sinan+; M??ft??, Ali*: +Northeastern University, Department of Mechanical, Engineering, 334 SN, MA 02115; * Tufts, University, School of Dental Medicine, Boston, MA, 02111
Northeastern University College of Engineering
Long-term stability of the dental implants strongly depends on the stress distribution characteristics of the implant-bone interface. The occlusal and masticatory loads acting on the prosthesis are transferred to the implant by means of abutment and result in non-uniform stress distribution in the bone. In order to maintain a healthy bone, stresses should be in the range of 1.4-5 MPa. Stresses outside this range have been reported to cause resorption of the bone tissue1. In this study, the stress distribution characteristics of five different implants from Bicon, Ankylos, Astra, ITI and Nobel Biocare subjected to an occlusal load located off the central axis are investigated. The dimensions of the implants were comparable in size; however the thread profiles were considerably different from each other.
The 2-D axisymmetric finite element models were loaded by 100 N vertical, 20 N lateral forces and 100 N.mm moment, separately and then the results are superposed to combine the effect of these loads to obtain the stress distribution due to a 102 N occlusal load 1 mm offset to the symmetry axis. The YoungÇƒÙs modulus of the bone was varied between 1 GPa (soft trabecular bone) and 16 GPa (hard cortical bone) in order to be able to investigate the success of the implants in different bone densities.
The Bicon and Ankylos implant systems seem to distribute the stresses more evenly when compared to Astra, ITI and Nobel Biocare implants in all bone densities. High localized stresses were found at the tip of the Astra, ITI and Nobel Biocare implants that can lead to crestal bone loss, however stresses generated at the other sites of implant-bone interface were low enough to prevent bone resorption.
1. Rieger M. R, Mayberry M, Brose M. O. Finite element analysis of six endosseous implants. J Prosthet Dent. 1990;63:671-6
This work was supported by Bicon Dental Implants, Boston, MA.