Irrigation With 0.06% Chlorhexidine in Naturally Occurring Gingivitis. II. 6 Months Microbiological Observations

I n an examiner blind positive/negative controlled 6‐month study, the efficacy of supragingival irrigation with 0.06% Chlorhexidine gluconate on the marginal and subgingival microflora in naturally occurring gingivitis was evaluated. The 222 patients enrolled in the study were assigned to one of four groups: Group 1: Once daily irrigation with 300 ml water followed by irrigation with 200 ml 0.06% Chlorhexidine gluconate (experimental); Group 2: Twice daily rinsing with 15 ml 0.12% Chlorhexidine (positive control); Group 3: Once daily irrigation with 500 ml water (irrigation control) and Group 4: Sodium fluoride dentifrice for normal oral hygiene only (negative control). All groups received the same sodium fluoride dentifrice for tooth brushing. All patients received a supra‐ and subgingival oral prophylaxis after baseline examination and at the end of the investigation. Plaque samples were analyzed from 105 patients at baseline, 93 patients at 3 months and 88 patients at 6 months. The 6‐months results demonstrated that, when compared with tooth brushing alone, adjunctive supragingival irrigation with 0.06% Chlorhexidine gluconate was most effective by significantly reducing ( P ≤ 0.008) both log 10 CFU and % of Gram‐negative anaerobic rods and black‐pigmented Bacteroides . Chlorhexidine rinse also significantly ( P ≤ 0.008) reduced log 10 CFU of black‐pigmented Bacteroides at 6 months. Both Chlorhexidine regimens significantly ( P ≤ 0.008) increased the % of Gram‐positive facultative cocci compared to water irrigation at 3 months. Water irrigation had a limited effect on any of the assessed bacterial groups (log 10 CFU and %). This study demonstrates that twice daily rinsing with 0.12% Chlorhexidine has a beneficial effect on the microflora of patients with naturally occuring gingivitis. Furthermore, once daily irrigating with 300 ml water followed by irrigation with 200 ml 0.06% Chlorhexidine has an incremental beneficial effect on the marginal and subgingival microflora of these patients. J Periodontol 1990 ; 61 : 427 – 433 .