5 ?? 0.24; P = 0.001, Student t test) and gingival index (0.44 ?? 0.15 versus 0.66 ?? 0.23, P = 0.021, Student t test) compared to the placebo group.Conclusion: These results suggest that mastic chewing gum is a useful antipl**ue agent in reducing the bacterial growth in saliva and pl**ue formation on teeth.