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

Abstract

The study was performed to histologically and immunohistochemically evaluate soft tis¬sue 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 re¬moval was performed. Biopsy samples were fixed in 10% buffered neutral formalin solu¬tion and embedded in paraffin blocks. Sections (4-6 μm) were obtained from the paraffin 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 tis¬sue of a dental follicle was 22%, and the incidence of dentigerous cyst was 52%, and the incidence of chronic nonspecific inflammatory tissue was 26%. Ki-67 expression was positive in 19 of 26 lining epithelia in cystic specimens, in 4 of 13 chronic nonspecific inflammatory tissue specimens, and in 0 of 11 healthy follicular specimens. These find¬ings 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 as¬sociated with radiographically normal third molar impactions. J. Exp. Clin. Med., 2012; 29:9-12