AbstractsBiology & Animal Science

Introduction When an implant is placed in the bone the body responds to the trauma by encapsulating the implant and its survival depends on the ability for hard tissue encapsulation. The stability of the implant during the healing phase is essential to achieve a good result [1]. Biological, physiological and mechanical phenomena affect implant stability. To achieve sufficient stability during the initial healing phase the implant has to provide sufficient static interaction with the bone. The static interaction might affect the biological processes that in turn affect implant stability. Although, numerous studies on the effect of dynamic interaction on implant stability and bone remodeling exist, the effect of static strain has yet to be clarified. As the healing progresses it may result in bone formation in close contact with the implant (i.e osseointegration) that stabilizes the implant. It has been found that implant surface modifications at the micro level promote osseointegration and that moderately roughened implants provide rapid and strong bone response [2, 3]. In addition, the application of nanostructures to an implant surface has been shown to elicit an initial complex gene response that may result in further enhancement in bone formation around the implant [4]. Furthermore the implant surface structure interlocks mechanically with the bone that affects the stability of the implant.The implant surface design has to take into account both biological and mechanical behavior of the tissues. Materials and methods To investigate how implant stability and the biological response are affected by an induced static load to the bone an in vivo study was performed. Two types of controlled static loads, excessive and moderate, were induced by specially designed implants. Two types of surface structure, turned and blasted, were applied on the implants. The implants were inserted in rabbits and healed for 3-84 days before the stability was measured by removal torque. To simulate how the pressure changes, due to biological and mechanical phenomena, on an implant surface that was subjected to an initial pressure, a constitutive model was developed that was comprised of visco-elastic, visco-plastic and remodeling components. The pressure on the surface in turn affects the implant stability. To investigate how the biomechanical and the biological responses are affected by the surface structure an in vivo study and a finite element analysis of the theoretical interfacial shear strength were performed. In the pre-clinical study, three groups of implants with different nano- and microstructures were compared to an implant with a control surface structure. The theoretical interfacial strength at different healing times was estimated by simulating the surface structure interlocking capacity to bone using an explicit finite element method. Simulations were performed for different surface structures and for different pressures, simulating visco-elastic and remodeling phenomena.Results…