Mouthrinses are used for a variety of purposes in dental and oral care including helping to prevent tooth decay and gum disease as well as finding application in the management of bad breath (halitosis) and dry mouth (xerostomia).
The current evidence suggests that while mouthrinses can be beneficial in the management of these conditions, they are not nearly as important as the effective removal of plaque by brushing and the control of dietary sugars in the cases of tooth decay and gum disease respectively. Where halitosis is concerned there are no scientific data that support (or contraindicate) the use of mouthrinses. Once again, it is good oral hygiene that is critical as the primary preventive measure.
Are there any downsides to using mouthrinses? Well, these can include staining of the teeth or taste disturbance but more seriously a link between alcohol-containing mouthrinses and oral cancer has been recently posited. The outcome of the research that has been done is that no clear-cut, causative associations appear to exist but that it may be prudent nonetheless to avoid alcohol-containing mouthrinses to reduce what is likely to be a very low risk overall.