Substantivity of a single chlorhexidine mouthwash on salivary flora: Influence of intrinsic and extrinsic factors

ObjectivesTo analyse the influence of intrinsic and extrinsic factors on the in vivo antimicrobial activity of a chlorhexidine (CHX) digluconate mouthwash on the salivary flora up to 7 h after its application, using epifluorescence microscopy.MethodsTen volunteers performed the following mouthwashes: 0.12% CHX (10 ml/30 s, 15 ml/30 s and 10 ml/1 min); 0.2% CHX (10 ml/30 s, 15 ml/30 s and 10 ml/1 min); 0.2% CHX (10 ml/30 s) plus different daily activities (eating, drinking, chewing or smoking).ResultsOn comparing 0.12% CHX (10 ml versus 15 ml), the greatest differences in bacterial viability were detected at 1 h and 3 h. On comparing 0.12% CHX (30 s versus 1 min) the greatest differences in viability were detected at 1 h, 3 h, and 5 h; and with 0.2% CHX (30 s versus 1 min), at 5 h and 7 h. On comparing 0.12% CHX (15 ml) versus 0.2% CHX (10 ml) and 0.12% CHX (1 min) versus 0.2% CHX (30 s), the percentage of viable bacteria was higher with the 0.12% concentration. On comparing 0.2% CHX versus 0.2% CHX plus daily activities, the higher differences were detected after eating and chewing, followed by drinking.ConclusionAn increase in the volume of 0.12% or 0.2% CHX mouthwashes does not affect the duration of antimicrobial activity in saliva, whereas increasing the duration produces a marked increase in substantivity. Substantivity was greater with 0.2% CHX than 0.12% CHX. Eating, chewing or drinking significantly reduces the 0.2% CHX substantivity in saliva.