Inducible Nitric Oxide Synthase Immunoreactivity in Denture Induced Fibrous Inflammatory Hyperplasia and Healthy Oral Mucosa: An Immunohistochemical Study

Excessive production of nitric oxide (NO) generated by inducible nitric oxide synthase (iNOS) has been implicated in the pathogenesis of numerous inflammatory processes. The exact pathogenesis of denture-induced fibrous inflammatory hyperplasia (DIFIH) remains unclear. The aim of this study was to assess iNOS expression in healthy Oral mucosa (HOM) and DIFIH by immunohistochemical (IHC) method. The expression of iNOS protein in HOM has been reported in numerous publications; particularly these tissues were used as a control group. However, there are some conflicting results whether healthy Oral tissues express iNOS. In this study performing IHC method, DIFIH (n= 26) and HOM (n= 28) in formalin-fixed, paraffin-embedded sections were evaluated in terms of iNOS expression. The statistical analysis showed that there were no significant differences between DIFIH and HOM regarding iNOS immunoreactivity (p>0.05). The results in this study indicate that iNOS does not have a determining role in pathogenesis of DIFIH. The constitutive iNOS expression in HOM under physiological conditions needs to be further evaluated.