Immunohistochemical evaluation of inducible nitric oxide synthase (iNOS) expression in the dental follicle, follicular cyst, and calcifying cystic odontogenic tumor

ObjectiveThe calcifying cystic odontogenic tumor (CCOT) is a benign cystic neoplasm with a variety of histopathological and clinical features in comparison with the follicular cyst. iNOS is an enzyme that produces free radicals and is a mediator regulator of the inflammatory response. It has been implicated in tumorigenesis as well. The aim of this study was to compare iNOS expression in the dental follicle and two odontogenic lesions with different aggressive behaviors.MethodsIn this cross-sectional study, 44 paraffin blocks were selected from the dental follicle, follicular cyst, and CCOT, and immunohistochemical staining was done by iNOS. The percentage and intensity of staining (total score) were calculated in the cytoplasm of the epithelial cells.ResultsThe highest total score of iNOS staining was found in the cytoplasm of the epithelial cells of CCOT when compared to the follicular cyst and dental follicle (p = 0.000). There was a significant difference in the final score between the follicular cyst and dental follicle (p = 0.001).DiscussionThe overexpression of iNOS in the CCOTs plays a role in its pathogenesis and iNOS, because of producing free radicals and damaging the oral tissue, may contribute to more aggressive behaviors of CCOT.