Effects of low dose chlorhexidine mouthrinses on oral bacteria and salivary microflora including those producing hydrogen sulfide.
OBJECTIVE
Clinical studies have demonstrated the considerable effects of chlorhexidine on dental plaque and oral microbiota as well as improvements in indices of oral health. This investigation examined the efficacy of lower concentrations of chlorhexidine.


METHODS
Mouthrinses with 0.03%, 0.06%, 0.12% chlorhexidine and a control rinse without chlorhexidine were examined. Alamar blue, an oxidation-reduction dye with fluorescent end-points proportional to bacterial viability, was used to determine bacterial viability. Further clinical studies examined the effects of these rinses on salivary bacteria and on bacteria producing hydrogen sulfide (H(2)S) and implicated in halitosis.


RESULTS
In laboratory tests, a significant dose-dependent effect was observed with Actinomyces viscosus as a model system using the Alamar blue procedure (P < 0.05). Clinical studies examined the effects 1.5 h and 3 h post-treatment on salivary bacteria and bacteria producing H(2)S. The first study compared the control rinse with the 0.03% and 0.06% chlorhexidine rinses; a second study compared the effects of the control rinse and the 0.06% and 0.12% chlorhexidine mouthrinses. In both studies, chlorhexidine rinses demonstrated significant dose-dependent effects post-treatment on salivary bacteria vs. the control rinse (P < 0.05). Significant decreases in H(2)S-producing bacteria were noted with these chlorhexidine rinses vs. the control rinse (P < 0.05).


CONCLUSIONS
The results highlight the dose-dependent relationships noted in laboratory and clinical tests which have potential implications for the use of lower doses of chlorhexidine to inhibit oral bacteria, including those implicated in halitosis.
Colgate-Palmolive Company, Piscataway, NJ, USA. prem_sreenivasan@colpal.com
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D016924:Actinomyces viscosus / Q000187:drug effects; D000328:Adult; D000368:Aged; D000891:Anti-Infective Agents, Local / Q000008:administration & dosage*; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism; D002710:Chlorhexidine / Q000008:administration & dosage*; D004396:Coloring Agents; D018592:Cross-Over Studies; D003773:Dental Plaque / Q000382:microbiology / Q000517:prevention & control*; D004305:Dose-Response Relationship, Drug; D006209:Halitosis / Q000382:microbiology*; D006801:Humans; D006862:Hydrogen Sulfide / Q000378:metabolism; D008826:Microbial Sensitivity Tests / Q000379:methods; D008875:Middle Aged; D009067:Mouthwashes / Q000008:administration & dosage*; D010078:Oxazines; D012463:Saliva / Q000382:microbiology; D014966:Xanthenes
D000891:Anti-Infective Agents, Local; D004396:Coloring Agents; D009067:Mouthwashes; D010078:Oxazines; D014966:Xanthenes; C005843:resazurin; D002710:Chlorhexidine; D006862:Hydrogen Sulfide