Int. Adv. Otol. 2009; 5(3); 301-309

Histopathological evaluation of the materials used for mastoid obliteration in rats: Allogeneic bone, allogeneic cartilage, demineralized bone matrix, and hydroxyapatite cement
Yoon-Seok Jang, Jung-Hong Park, So-Hyang Kim, Tae-Woo Gu, Jong-Chul Hong, Myung-Koo Kang

Department of Otorhinolaryngology-Head and Neck Surgery, Dong-A University College of Medicine, Busan, Korea, mgkang@dau.ac.kr

Hypothesis: This study was conducted to evaluate the histopathological changes in bone, cartilage, demineralized bone matrix
(Regenafil) and hydroxyapatite cement (Mimix) used in mastoid obliteration (MO) after 1 year.

Background: Many techniques and obliterating materials have been described for use in MO. The ideal material for MO maintains
good biological support during healing and is then replaced gradually by the newly formed autogenous tissue. Although
there are many reports on the obliterating materials used for MO, few published comparisons of the long-term changes associated
with natural and artificial materials are available.

Materials and Methods: Forty rats received mastoid bulla obliteration using the four materials. Each materials group was subdivided
into two groups according to whether the mucosa was removed or conserved. New bone formation, state of the obliterating
materials, inflammatory response and mucocele formation were evaluated on each side.

Results: In the mucosa-removal groups, the newly formed bone areas were significantly greater in the bone, cartilage and
Regenafil groups than in the Mimix group (p = 0.001). In the mucosa-conservation groups, the newly formed bone areas were
significantly greater in the bone and cartilage groups than in the other groups (p < 0.001). The bone and Regenafil groups
showed significant differences in new bone formation between the mucosa-removal and mucosa-conservation groups (p =
0.016 and p < 0.001, respectively). All bone grafts exhibited definite collapse into the bulla at the edge of the surgically created
bony defect, compared with the groups obliterated with other materials. The Mimix group showed a marked inflammatory
response around the residual material. Mucocele formation was significantly greater in the bone and Regenafil than in the other
materials (p < 0.001).

Conclusion: Our study shows that cartilage, bone and Regenafil are appropriate graft materials for MO in the rat and that cartilage
is suitable for MO in the mucosa-conservation condition. Mimix HA cement was unsatisfactory for MO in the rat.