Computational simulation of piezo-electrically stimulated bone adaption surrounding activated tooth implants
|Bearbeitung:||M. Sc. Seyed Alireza Shirazi Beheshtiha, Prof. Dr.-Ing. Udo Nackenhorst|
|Förderung durch:||State of Lower Saxony|
This study aims for the development of active implants which provide additional electrical stimulation for bone adaption. A computational framework is presented in order to optimize new developments for activating dental implants with piezoelectric coatings. An electromechanical driven bone remodeling theory is developed and implemented into a finite element program. The osseointegration of bone implants is simulated by means of bio-active interface theory. Detailed numerical studies are performed based on a 3D model of lower mandible which has been reconstructed from high resolution CT-data. Initial relative motion, called micromotion, is limited as an important parameter for the osseointegration because excessive micromotion causes apposition of fibrous tissue.
A modeling approach is introduced considering both electrically and mechanically stimulated time dependent ingrowth with regard to simultaneous assessment of the micromotion threshold violation under dynamic chewing loads. The combined Drucker-Prager with Von Mises yield criterion is introduced for the simulation of osseointegration process based on robust and established methods of plasticity theory. The linear theory of piezoelasticity is implemented into the finite element program for coupled electro-mechanical modeling.
Furthermore, the influence of an additional piezoelectric coating of the implant is investigated. In this case,the electric field strength produced by piezoelectric coating due to normal chewing conditions is of significant importance, as rather low field intensity doesn't affect on bone cell proliferation while quite excessive fields might cause cell necrosis. Therefore, a parametric study has been carried out in order to achieve suitable material properties of piezoelectric coating to provide electric field in tolerable domain.