Understanding and enhancing the mechanical performance of bioinspired zirconia-based dental materials

Oral disease such as tooth decay is one of the major healthcare challenges that affects over 40% of the world's population and over 30% of dentate adults in England. Such disease can lead to a loss of function in teeth that can impair diet and have undesirable consequences for general health. It can also lead to a loss of aesthetics in teeth, which adversely influences social activity of the patients. Both function and aesthetics can be restored with dental crowns (e.g. porcelain-veneered zirconia frameworks), which can also help prevent patients from experiencing pain, sensitivity and infection. Driven by the ageing population in the UK who need complex dental care to restore and maintain their teeth throughout their lives, as well as the fact that over 37% of dentate adults in England have one or more crowns, there has been a growing demand for patient specific dental restorative products (e.g. dental crowns) with increased longevity. Despite a continuous improvement in the mechanical performance, the conventional porcelain-veneered zirconia frameworks still suffer from a high failure rate (approximately 6-15% over a 3- to 5- year period). The primary failure mode of these dental crowns is near-interface chipping of the porcelain veneer, due to the loads that are applied to the chewing or grinding surface of the crown during mastication (referred to as occlusal loads). Failure of dental crowns can cause extensive discomfort to patients and have high cost implications for both patients and clinicians. To alleviate the problem, it is therefore highly desirable to develop novel porcelain-free zirconia-based dental restorative materials with significantly improved resistance to cracking. Inspiration for these composites can come from natural teeth, which have an intricate architecture giving them remarkable mechanical properties, especially the resistance to fracture - particularly in tooth enamel. Tooth enamel has been shown to have graded microstructure and extraordinarily strong interfacial bonding to the resilient supporting dentine.

In this project, we propose to understand and improve the mechanical performance of novel zirconia-based composites with bioinspired functionally graded and textured microstructures. Our aim is to mimic the structure and remarkable mechanical properties of natural tooth enamel. The improvement of the mechanical performance will be based on a fundamental understanding of the role of bioinspired microstructural features in determining the mechanical properties, and how the properties can be enhanced by microstructural optimisation. To achieve this, we will develop and implement advanced micro-scale mechanical and structural characterisation techniques and micromechanical modelling. We will be working in close collaboration with academic and industrial collaborators and receive clinical input. The outcomes of this project will direct the manufacturing and processing towards biomimetic materials design and optimisation for the development cycle of the next generation dental products. Patients suffering from dental disease will benefit from this work through far-reaching improvements in the state of health, personal happiness and quality of life.

The growing number of patients suffering from dental decay leads to a significant reduction of productivity and considerable cost to the NHS (£3.4bn per year in England). The global market for restorative dentistry has been predicted to exceed $20bn by 2024. With considerable market potential, improvements in the effectiveness, reliability and cost reduction through increased longevity of bioceramic-based dental crown materials could bring tangible economic benefits to the UK. This would occur through the development of advanced prosthodontics and functional restorative procedures and far-reaching improvements in the state of health, personal happiness and quality of life for patients suffering from dental disease. Clinicians will also benefit from increased confidence in delivering increased longevity of the aesthetic dental restorations. Efforts will be made to make the key findings accessible in appropriate open source media to ensure that the major patient and clinician beneficiaries have access to the outcomes. The economic and societal impact will not be confined to the UK but will also contribute to the advancement in therapies and treatments across the globe.

The novel healthcare technologies theme is a key priority for the UK to maintain and enhance its world-leading position and competitiveness in many aspects of scientific and industrial healthcare research. The insights obtained in the proposed characterisation and evaluation of the structure-property relationship of novel zirconia-based dental restorative materials will be made directly accessible to the collaborative partners: the University of Bristol, the National Physical Laboratory (NPL) and the Agency for Science, Technology and Research (A*STAR). In addition, the close links and engagement with academics and clinicians at the School of Dentistry at the University of Birmingham will provide timely clinical insights and experience for the project, and in the long-term will facilitate incorporation into clinical practice and enhance the clinical performance of zirconia-based dental restorations. The translation will help maintain the existing partnership and develop future links.

The training and continued professional development of the postdoctoral research assistant (PDRA) and two university funded PhD candidates will benefit their transition into further academic posts and/or industry. They will gain relevant skills and experiences which include cutting-edge materials science knowledge, advanced characterisation techniques, micromechanical modelling activities, appropriate supervision experience and networking opportunities with clinicians. Students from the BEng/MEng programmes as well as two MSc programmes (Advanced Materials MSc and Biomedical Engineering MSc) in the Mechanical Engineering Sciences Department at Surrey will benefit from cutting-edge research challenges, and may continue towards doctoral study.

The public impact of the project will be ensured through public outreach and a comprehensive programme of publication and presentation of the research originality and novelty in high-impact multidisciplinary peer-reviewed journals and (inter)national conferences. This will attract more researchers and academics from the biomaterials and biomedical engineering community and stimulate further growth of studies on products demonstrating biocompatibility in dentistry, both in the UK and worldwide.