Biomaterials for prosthetics
Glass-ceramics have been invaluable in dentistry for many years, but solubility and biocompatibility problems that have limited their use as biomaterials. Colleagues in Materials Science & Engineering and the School of Clinical Dentistry are currently synthesising new glass-ceramics that overcome these problems.
Glass ionomer cements have been used for some time in dentistry. They form strong bonds between dentine and the restoration, and are able to set when wet. Fluoride ions are released during the setting process, which act to sterilise the bond, leading to a durable repair in the mouth. In the 1990′s these materials were seized upon by surgeons looking for materials they could use to mend or replace missing bone in the body.
Researchers at Sheffield predicted from model studies that the existing formulations would not, however, be compatible with general surgical applications, as the ion release killed the bone around the application. Work at Sheffield has subsequently focussed on developing a new family of GICs with reduced toxicity and better osteoconductivity for bone repair.
High impact acrylics such as Poly Methyl Methacrylate (PMMA) have been the standard materials for making dentures since WW2. They have good aesthetic properties, and are easy to make. Unfortunately, these materials have poor strength, and many dentures have to be repaired within the first year of service. Current research is focussed on improving the service life while retaining ease of manufacture.
Top right: An electron micrograph showing an osteoblast (false coloured in blue) colonising a biomaterial being developed for implant surgery.
Bottom right: A transmission electron micrograph showing the dendritic microstructure of an iron containing glass ionomer cement, developed at Sheffield. Scale bar 1µm