Fig 1: Immunohistochemical analysis of biofilm exposed RHG. (a) Histology of healthy native gingiva. Histology (hematoxylin and eosin staining, H&E) and immunohistochemical staining with antibodies against PCNA, Ki67, Elafin and HBD-2 is shown. (b) RHG were exposed topically (surface application) to either multi-species biofilm or control medium without biofilm and harvested 1 or 7 days hereafter. Histology (H & E) shows thicker epithelium at day 7 in RHG exposed to biofilm compared to control RHG. Immunohistochemistry shows increased proliferation (PCNA, Ki67), Elafin and HBD-2 in biofilm exposed RHG compared to control RHG at day 7. Figures are representative of at least three independent experiments, each with an intra-experiment duplicate.