The in vitro interfacial mechanics of a bioactive composite for mandibular construction

We investigated a bioactive composite of hydroxyapatite (HA) and polymethylmethacrylate (PMMA) as a mandible replacement. We introduced a coupling agent to improve the adhesion properties at the HA/PMMA interface. Via the application of nano-indentation onto various positions of the cross section of composite, we will be able to determine the influence of the coupling agent on the local mechanical properties of the system before and after in vitro immersion conditions. Also under field emission environmental scanning electron microscopy, we analyzed each indent mark at up to 5000x magnification. Coupling the microscopical analysis with the load-displacement curve allowed us a more comprehensive local analysis than has previously been accomplished. The in vitro mechanical properties of the hydroxyapatite particulates showed a reduction of bulk bending properties, local elastic modulus and local hardness with increase of immersion time. While the coupling agent unproved the interfacial mechanical properties up to 24 hours immersion, it did not effect the surface bioactivity of the system.