ABSTRACT
Chronic dental periapical lesions resulted from chronic inflammatory response to the periapical tissues. Since T-helper [CD4+Y] cells are the prominent cells in these lesions, so the aim of this study was to determine the correlation between the concentration of IL-4 and IL- 12 [most important cytokines for differentiation of T helper 2 and T helper 1 cells, respectively], and the diameter of chronic periapical lesions. Thirty-eight chronic periapical lesions were collected which 18 periapical lesions had diameter of >/= 5 millimeter [case group] and 20 periapical lesions had the diameter <5 millimeter [control group]. Tissue samples were cultured for 72 hours, then ELISA [Enzyme linked immuno-sorbent Assay] was used for determining the concentration of IL-4 and IL- 12 in supernatant fluids. Mann-whitney U and Spearman correlation tests were used to analyze the data. IL-4 and IL- 12 were found in all of samples. There was no significant difference between case and control groups regarding the concentration of IL-4, IL- 12 and IL-4/IL- 12. The only significant correlation was between IL-4 and IL-6 concentration without any regard to the diameter of lesions [P<0.001] [Spearman correlation coefficient=0.593]. It is concluded that in chronic periapical lesions, probably T helper 1 and T helper 2 cells participate in active phases of inflammation and tissue damage equally. This could be resulted from mixed population of bacteria in these lesions