Ki-67 expression in pericoronal tissues of impacted mandibular third molars

The study was performed to histologically and immunohistochemically evaluate soft tissue pathologic changes in pericoronal epithelial tissues of impacted mandibular third molars that did not exhibit pathologic pericoronal radiolucency and to clarify the role of ki-67 expression for separation between healthy follicle and dentigerous cyst. fifty pericoronal tissues associated with completely impacted mandibular third molars were submitted for histologic examination by each of 2 pathologists after surgical tooth removal was performed. biopsy samples were fi xed in 10% buffered neutral formalin solution and embedded in paraffi n blocks. sections (4-6 μm) were obtained from the paraffi n block and to evaluate the expression of ki-67 sections were immunostained anti-ki-67 primary antibody and streptavidin-biotin complex system. the incidence of normal tissue of a dental follicle was 22%, and the incidence of dentigerous cyst was 52%, and the incidence of chronic nonspecifi c infl ammatory tissue was 26%. ki-67 expression was positive in 19 of 26 lining epithelia in cystic specimens, in 4 of 13 chronic nonspecifi c infl ammatory tissue specimens, and in 0 of 11 healthy follicular specimens. these fi ndings suggest that the majority of cystic specimens demonstrated proliferative activity, therefore the incidence of dentigerous cyst associated with impacted third molar teeth is high and proliferative marker may be played a role in diagnosis of dentigerous cyst associated with radiographically normal third molar impactions.