PhDIt is desirable for a dental restorative material to have bioactive and bonding properties.
This study focuses on the synthesis of a covalently-linked polyurethane/nanohydroxyapatite
(PU/nHA) composite and evaluates its chemical, physical, thermal and
biochemical characteristics.
nHA powder was produced from the sol-gel and novel composite material was
chemically prepared by utilising solvent polymerisation. The resulting composites were
analysed by chemical, thermal, and mechanical characterisations and electrospun to
form fibre mats. The composites were hydrolytically degraded in deionised water and
phosphate buffer solution (PBS) and were analysed. Bioactive behaviour was
determined in modified-simulated body fluid. The bioadhesion with dentine was
analysed in distilled water and artificial saliva. Cell growth and proliferation was
measured and number of adhering bacteria was determined and serial dilution followed
by plating for colony forming units per disc.
Spectral analyses showed the grafted isocyanate and ether peaks on nHA indicating that
urethane linkage was established. Covalent-linkage between nHA and PU were found in
this novel composite with no silane agent. The physical and thermal properties were
enhanced by nHA. These composites had high resistance toward hydrolysis and little
degradation was observed. Bioadhesion and bioactivity analysis showed the composite
adhered firmly on the tooth surface (dentine) and bond strength was similar to existing
obturating material. Higher nHA content composite showed a thicker layer of adhesion.
Cells were proliferated although at a lower rate of growth compared to PU, whereas,
there was reduction in bacteria adhering to the grafted composite compared to PU. With
its low bacterial adhesion and biocompatibility it may provide a promising solution to
reduce infections. The electrospun nano-fibres were successfully developed and
revealed no loose nHA particles. Hence, this novel composite has the potential to be
used as a bioactive dental restorative material
