Cariostatic activity of (1,6-bis-[2-ethylhexylbiguanido]-hexane) in conventional rats

The antimicrobial and cariostatic activities of the dihydrochloride and dihydrofluoride salts of alexidine (1,6-bis-[2-ethylhexylbiguanido]hexane) were compared to those of chlorhexidine acetate and sodium fluoride in rats implanted orally with Streptococcus mutans 6715 and fed a cariogenic diet. Experimental caries was significantly reduced by the continuous administration of low concentrations of biguanides via the drinking water, but this was accompanied by increased staining of the molars. Very high biguanide concentrations, applied infrequently, directly to the molars, effectively reduced caries and resulted in less staining. A combination of alexidine dihydrochloride and sodium fluoride offered no advantage over either drug alone. Alexidine salts prevented the progressive increase in implanted S. mutans, whereas chlorhexidine acetate practically eliminated the micro-organism from the oral cavity. Sodium fluoride had no effect on the implanted flora. It was concluded that alexidine salts are comparable in cariostatic activity to chlorhexidine. The tooth staining accompanying the use of bisbiguanides can be reduced by adjusting the concentration of the drug and its frequency of application.