Group C subjects will be instructed to apply 0.2 % Chlorhexidine gel (clinica gel) on the marginal gingiva after morning tooth brushing for 30 minutes and 0.8 % metronidazole gel (anaerobic gel) after evening tooth brushing for 30 minutes for two weeks. Subjects in these groups will receive the detailed and precise instruction and demonstrations on the diurnal alternate application of the two gels.