Learning Objectives:

Purpose: Canal wall down mastoidectomy is often performed to prevent recurrence and complete removal of lesion in the treatment of otitis media with cholesteatoma. In this case, however, several problems can be caused to the mastoid cavity. Therefore to improve the long term stability of the mastoid cavity and to eliminate the cavity related problems significant modifications were introduced such as the mastoid obliteration technique using various methods including bone, cartilage, fat, flaps and others. This study evaluated the effectiveness of hydroxyapatite/chitosan patch(HAp/Chi patch) known as the new materials to promote osteogenesis for mastoid obliteration in animal model.

Materials and Methods: Sprague-Dawley rats underwent mastoid obliteration using hydroxyapitie powder(Mimix^®), cartilage and HAp/Chi patch in each five ear. CT (computed tomography) and mastoid tissue sampling was done after twelve weeks. And we evaluated the degree of osteogenesis and inflammation of tissue.

Results: The mastoid cavity in HAp/Chi patch group was best filled in CT findings. In the histopathological aspects of the osteogenesis and inflammation, it exhibited 7.5%/20%, 28%/3% and 25%/50% in the group of cartilage, hydroxyapitie powder and HAp/Chi patch group, respectively.

Conclusions: Hap/Chi patch is less absorbent, better to fill the mastoid cavity and more induce osteogenesis than the other obliteration material. But the degree of inflammation in Hap/Chi patch group is highest. It may be necessary to secure the stability of the mastoid obliteration material through additional experiments.