Correlation Between Proinflammatory Cytokine Expression and Clinical Data in Apical Granuloma

This study was intended to evaluate the expression of inflammatory cytokines commonly secreted by CD4+ T cells (IL-2, IL-5, IL-17, TGF-β, TNF-α, and IFN-γ) in apical granulomas and correlate with the clinical conditions and time elapsed since root canal treatment.

Eighteen biopsy specimens obtained by periradicular surgery of teeth with post-treatment apical periodontitis and diagnosed as apical granuloma were available from the oral pathology laboratory. Silanized slides containing paraffin sections were used for immunohistochemical reactions. Images were analyzed by using an optical microscopy and each slide was subdivided into 5 fields at high magnification.

IFN-γ and TGF-β were the cytokines with the highest expression levels. There were statistically significant differences when comparing IL-2 and IFN-γ (P < .05), and IL-2 and TGF-β (P < .05). Comparison between the detected cytokines and clinical data and time of treatment demonstrated significant correlation (P < .05) between lower expression of IL-2 and the presence of painful symptoms, absence of sinus tract, and treatments performed more than 4 years before. It was also possible to observe a significant correlation between lower expression of IL-5 and treatments performed less than 4 years before (P < .05).

IFN-γ and TGF-β were highly expressed in apical granulomas. However, only IL-2 and IL-5 levels were associated with clinical data and time since previous root canal treatment.