Introduction: Radicular Cyst (RC) development is associated with the activation and proliferation of epithelial rests of Malassez. This occurs due to inflammatory stimuli resulting from bacteria proliferation in the root canal of a non-vital tooth. When the tooth is removed, the cyst becomes known as Residual Cyst (ReC). The RC common treatment is the endodontic therapy, with the aim of eliminating the inflammation in the periapical region. Nonetheless, this treatment is not always effective and the cyst may continue to grow, what happens in most cases of ReC.Objective: To evaluate the metabolism of the RC and ReC epithelial lining through the technique of AgNOR quantification and of the influence of the presence of inflammation in the growth of these cysts.Material and method: 20 cases of RC and 10 of ReC, were processed by the AgNOR technique. The AgNOR quantitative analysis was performed using the "Counting cells" software. The statistical post-hock Newman-Keuls test was applied to compare the RC and ReC mean number of AgNORs in inflamed and non-inflamed areas.Result: Statistically significant difference (p=0.0094) was observed between inflamed (1.86±0.26) and non-inflamed (1.65±0.20) areas. No statistically significant difference (p=0.37) was observed in the comparison between RC (1.81±0.28) and ReC (1.73±0.16).Conclusion: Inflammation interferes in the epithelial metabolism of RC and ReC, reflectings the action of growth factors in epithelial proliferation and contributing to the growth of the cyst, regardless the presence of the etiologic factor associated with the injury origin.