ANNs were 90%–98% accurate for periodontitis (AGP or CP) by using immunological cell markers. Datasets of CD4/CD8 cell ratio, levels of CD3 cells, eosinophil, neutrophil, monocyte and lymphocyte counts. The levels of IL‐1, IL‐2, IL‐4, INF‐γ and TNF‐α released from monocytes; and antibody levels against A. actinomycetemcomitans and P.gingivalis were noted. An ANN obtained the best prediction with cross‐entropy values of monocyte, eosinophil, neutrophil counts and CD4/CD8 ratio as inputs. The gene discussed is IL4; the disease is periodontitis.