A major goal of spine implants is to remove the disabling pain caused by pinched nerve or joint pain associated with abnormal movements of the vertebrae. One attractive strategy to alleviate the associated suffering is the lumbar disc prosthesis that would restore mobility. The prosthesis materials must resist wearing, fatiguing and shocks for years in a human body environment. In oral implants development, tooth-coloured ceramic materials might be successful if they prove to be strong, stable and well integrated in the jaw bone. Zirconia-based ceramics are the only materials able to couple high-stress resistance and fracture toughness, thus representing the best option for such demanding clinical devices. The aim of the EU-funded LONGLIFE (Advanced multifunctional zirconia ceramics for long-lasting implants) project was to develop new oral and spine implants with perfect reliability and a lifetime longer than 60 years. The major challenge for these kinds of implants is osseointegration, the formation of a direct interface between an implant and bone without intervening soft tissue. Modifications of zirconia-based surfaces aimed to improve bone integration and to decrease the risk of bacterial adhesion. Consortium members developed and patented an innovative engineering route for the synthesis of multiphasic composite powders and materials with complexity and grain refinement never reached before. Optimisation of the process led to the fabrication of tough and strong composites with a high degree of stability. Biological responses of new materials and surfaces were assessed in complex in vitro testing using co-culturing with the components of saliva in the oral cavity. The LONGLIFE composites demonstrated the highest degree of bone integration combined with the lowest degree of bacterial adhesion. Specifications for dental and spine implants were critically reviewed, and new designs and prototypes have been produced. Analysis of both dental and spine implants under the complex loading comparable to in vivo conditions was performed. Implants have been tested under multifunctional approaches combining wear, shocks and ageing in the case of spine implants and fatigue and ageing in the case of dental implants. In conclusion, the LONGLIFE consortium developed technology for the synthesis and evaluation of new composite materials and surfaces for the implants. Successful project developments enable the creation of an 'implant for life' and will help to avoid costly and high-risk revision surgeries.
Dental implants, spine implants, LONGLIFE, zirconia ceramics, osseointegration