Effect of in-vitro fluoride ion treatment on the mechanical properties of bone tissue

Cortical bone tissue has been modeled as a short fiber reinforced composite material. It is composed of an organic matrix comprised mainly of Type 1 collagen reinforced by a mineral crystal similar to carbonated hydroxyapatite. We have developed an in-vitro ion treatment method to alter mechanical properties of the bone tissue using fluoride ion solutions. When bone is exposed to a high ionic strength fluoride solution, part of the bone mineral dissolves and precipitates as calcium fluoride. Changes in the mechanical properties such as, elastic modulus, ultimate stress and ultimate strain are dependent on the concentration and the pH of the treatment. Mechanical properties of fluoride treated (high ionic strength) bone tissue showed that elastic modulus, yield stress and ultimate stress are reduced in comparison to the controls. However ultimate strain increased considerably as compare to controls indicating that there might be a slippage between the bone mineral and the organic phase.