Histopathologic Evaluation of Obliterating Materials in the Temporal Dorsal Bullae of Rat

Ahn, Joong Ki; Kang, Myung Koo; Park, Heon Soo

Abstract

BACKGROUND AND OBJECTIVES: Mastoid obliteration is the technique to reduce disadvantages of canal wall down procedure. Many materials for mastoid obliteration have been devised. The aim of our study is to evaluate the histopathologic changes according to the different obliterating materials and removal of the mastoid mucosa in the temporal bullae of rat. MATERIALS AND METHOD: We divided rats into two groups. One group underwent removal of mastoid mucosa with 2% TCA (trichloroacetic acid), and the other was left untreated. Both groups had mastoid obliteration by implantation of bone wax, xenograft bone material (Lubboc(R)), or homologous corticocancellous bone. Twelve weeks after implantation, the animals were sacrificed. Histopathology study was performed to evaluate inflammation, foreign body response, new bone formation, implant material resorption, and mucocele formation within the bullae.
RESULTS
Histopatholgoic evaluation revealed many instances of inflammation and foreign body response in the groups using the bone wax. In rats implanted with xenograft bone material or homologous corticocancellous bone, by contrast, microscopic examination showed new woven bone ingrowth at the bone implant interface. Especially, homologous corticocancellous bone showed good results. Rats not treated with 2% TCA showed the presence of mucocele.
CONCLUSION
We suggest that homologous corticocancellous bone is the better obliterating material than bone wax or xenograft bone material. And also, all mastoid lining mucosa should be removed prior to implantation in mastoid obliteration surgery. Further research will be necessary to determine the sequence of morphologic changes that occur in mastoid bullae mucosa.