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

Abstract

Objectives: To 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 7h after its application, using epifluorescence microscopy.

Methods: Ten volunteers performed the following mouthwashes: 0.12% CHX (10ml/30s, 15ml/30s and 10ml/1min); 0.2% CHX (10ml/30s, 15ml/30s and 10ml/1min); 0.2% CHX (10ml/30s) plus different daily activities (eating, drinking, chewing or smoking).

Results: On comparing 0.12% CHX (10ml versus 15ml), the greatest differences in bacterial viability were detected at 1h and 3h. On comparing 0.12% CHX (30s versus 1min) the greatest differences in viability were detected at 1h, 3h, and 5h; and with 0.2% CHX (30s versus 1min), at 5h and 7h. On comparing 0.12% CHX (15ml) versus 0.2% CHX (10ml) and 0.12% CHX (1min) versus 0.2% CHX (30s), 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.

Conclusion: An 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.