In our analysis the CAT activity was significantly reduced in PPL samples to respect controls, this decrement in CAT activity was reported by Sima C, et al. but in oral neutrophils isolated of severe chronic periodontitis (24) in opposition to reported by Esposito P. et al that showed a significative increment of CAT activity in patients with inflamed pulp tissue specimens (25). The gene discussed is CAT; the disease is chronic periodontitis.