Abstract
Experimental composite films made from chitosan and hydroxyapatite were examined as to if the films could be used as a bone substitute material. Neutralized film, at pH 7.4 (ASF), and the film that was titrated to pH 7.2 (TRF), using malic acid and sodium polyphosphate acid solutions, were prepared. Films soaked in Ringer's solution were also fabricated. These films were immersed in a physiological saline solution for up to 8 weeks.The tensile strength and elongation of test specimens, the pH values of the solution, and the amounts of Ca, P, Na, and K ions from the films into the solution, were determined. The surfaces of films before and after immersion were examined using SEM. The following results and conclusions were obtained:
1. The longer the immersion time, the lower the tensile strength and elongation of the films.
2. The pH values of the solution in which ASF and TRF films were immersed were slightly lower than those in which the films soaked in Ringer's solution were immersed.
3. The dissolved amounts of Ca, P, and K increased with prolonging of the immersion period.
4. The surfaces of film hydroxyapatite particles in film were covered with chitosan before immersion, while no chitosan was found on the hydroxyapatite particles after immersion, and,
5. Although the dried films showed cookie-like brittleness, the films soaked in water had elastic properties like a rubber material. Those elastic films can be trimmed into any forms using scissors or a surgical knife. Thus, these films can be bone filling material between alveolar bone and the alveolar ridge. In addition, the experimental films show radiopacity, because of the hydroxyapatite particles in the film.
