Apoptosis-related factors in the epithelial components of dental follicles and dentigerous cysts associated with impacted third molars of the mandible

Objective. Radiolucencies adjacent to the crowns of impacted third molars can represent follicular remnants or cysts. To clarify the possible role of apoptosis-related factors in pericoronal odontogenic tissues, expression of Fas, bcl-2, and single-stranded DNA (ssDNA) was examined in epithelial components of dental follicles (DFs) and dentigerous cysts (DCs) associated with impacted third molars of the mandible. The results were compared with immunoreactivity for Ki-67, a marker of cell proliferation. Study design. Specimens of 80 DFs and 27 DCs were examined immunohistochemically using antibodies against Fas, bcl-2, ssDNA, and Ki-67. Results. Expression of Fas and ssDNA was detected in superficial epithelial cells of DFs and DCs. Expression of bcl-2 and Ki-67 was found in epithelial cells neighboring the basement membrane. The positive ratio of bcl-2 in DFs was significantly lower than that in DCs. ssDNA-positive cells were slightly more numerous in DFs, while Ki-67-positive cells were slightly more numerous in DCs. In DFs, epithelial tissues with proliferative rete processes showed significantly higher Ki-67 labeling than did those without proliferative rete processes. DFs with marked inflammatory changes showed slightly higher rates of ssDNA and Ki-67 positivity than did DFs without marked inflammation. Conclusions. Apoptosis-related factors and proliferative marker differ between DFs and DCs. Apoptosis and cell proliferation may play a role in the pathogenesis of DCs. In DFs, expression of apoptosis-related factors and proliferative marker is most likely modulated by the morphologic characteristics of epithelial components as well as by inflammatory changes.