Laboratory-based biomaterials research is essential to the genesis and development of new and improved biomaterials for dentistry and orthopaedics. The questions requiring resolution far exceed the worldwide resources available for Randomised Clinical Trials. Hence, careful and appropriate laboratory modeling is also needed to replicate key features of the oral environment, including its biomechanical, thermal, optical, chemical, biochemical and cellular aspects. Recent publications address all of these dimensions of research, and contribute to an enhanced mechanistic understanding of biomaterial behaviour.
Research interest involves the whole field of dental and orthopaedic biomaterials, but especially in polymer systems, composites and adhesives. Biomaterials for dental operative use entail special 'boundary conditions' on account especially of in situ solidification, micro-engineered small quantities and constrained cavity-filling placement. This research has also branched into cognate areas including Acrylic Bone Cement and Medical/Photonic adhesives.
The following specific topics are illustrative of our interdisciplinary research:
- The stability of interfaces between host tissues and restorative biomaterials is crucial. Substantial advances have been made in tissue-engineering the interface of hard substrates such as dentine and bone, but these hybrid bonding zones are challenged clinically by the rapid development of intra-coronal and intra-femoral stresses arising from molecular setting processes. Our laboratory has had a major world-wide impact upon the measurement and understanding of these polymerisation-shrinkage phenomena, especially in the dynamics of photo-polymerisation. Photo-activation methods, based on LED light sources, have now been deployed and these are being carefully evaluated, along with composite biomaterials based around novel chemistry and systematically-varied formulations.
- Metal-free biomaterials - required to withstand functional stresses - are usually designed around composite structures and/or high performance ceramics. These cannot be dissolved so as to apply classical analytical methods. Investigation of their behaviour and internal microstructures, down to the molecular and nano-scales requires development of appropriate spectroscopic, viscoelastic and image-analysis techniques. We deploy several experimental methods, including Photo-DSC, FTIR, Rheology, XRD, XRF, X-Ray 3-D micro-tomography and Fracture-Mechanics, for this purpose.
- Natural bio-composites utilise fibres as well as particulate ceramics for reinforcement. We are collaborating with researchers from Finland in developing user-friendly, economical and strong fibre-reinforced biomaterials for applications in endodontics, temporary restoratives and fixed and removable prosthodontics.
- Clinical placement of biomaterials is greatly affected by their perceived ease of handling and manipulation in vivo. However, these clinical impressions are frequently highly subjective and non-transferable. We have made pioneering strides to develop in vitro quantitative methods of measuring elusive properties such as stickiness and packing behaviour of un-set materials. Our approach has involved the design of novel scientific instrumentation.
- Aesthetic dentistry relates to the optical properties of biomaterials, which also depends on their surface morphology and their internal microstructure. We use a combination of scanning-probe (atomic force), electron and optical microscopies and photo-electron spectroscopy to investigate surface changes.
- Electrospinning of treated nano/micro-sized polymer fibres is being used for (i) promotion of bone growth for defect repair and (ii) drug delivery in periodontology.