Rat Mastoid Bullae Obliteration with Hydroxyapatite: Histopathologic Results with Various Size of Hydroxyapatite / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: Mastoid obliteration is the technique developed to reduce cavity problems after canal wall down mastoidectomy. Different materials have been explored for the technique, and of the variety of materials that have been used for mastoid obliteration, hydroxyapatite has gained particular attention. Hydroxyapatite can be made into a specific particle size, which affects the postoperative result. The aim of this study is to evaluate the histopathologic findings of mastoids obliterated with various particle sizes of hydroxyapatite in the temporal bullae of rat. Materials and Method: Rat bullaes were obliterated with hydroxyapatite and diversified into different particle sizes. In group 1, the mastoids were obliterated with Mimix(R) powder and in groups 2, 3, 4 with Bongros(R). The particle sizes were 0.3-0.6 mm, 0.6-1.0 mm and 1.0-3.0 mm each. After 3 months, the mastoids were examined under the microscope. RESULTS: In group 1, a new bone was formed in a consecutive fashion from the mastoid wall toward the center of the mastoid; there was no inflammation, with the new bone formation constituting 15%. In group 2, 3, 4, the proportion of new bone formation was higher than in the group 1, and constituted 40%, 55% and 60%, respectively. Inflammation was more severe when the particle size became larger. CONCLUSION: New bone formation was faster if larger hydroxyapatite particles were used; however, inflammation also increased. The powder form of hydroxyapatite was slow in new bone formation, but there was little inflammation. We therefore think that the hydroxyapatite is a very safe material.