While there is tentative benefit from the use of a tongue cleaner it is insufficient to draw clear conclusions with respect to bad breath. A 2006 Cochrane review found tentative evidence of decreased levels of odor molecules.
Some studies have shown that it is the bacteria on the tongue which often produce malodorous compounds and fatty acids that may account for 80% to 85% of all cases of bad breath. The remaining 15% to 20% of cases originate in the stomach, from the tonsils, from decaying food stuck between the teeth, gum disease, dental caries (cavities or tooth decay) or plaque accumulated on the teeth. In addition, degradation of oral debris by microorganisms produce organosulfur compounds (volatile sulphur compounds) on the posterior (rear) of the tongue.
The tongue is normally pink in appearance. It may acquire a white or colored coating due to diet, reduced salivary flow, reduced oral hygiene or tongue anatomy. The thickness of the tongue coating can also vary. Tongue cleaning can reduce this coating to make it cleaner and to help return it to its natural pink color.
Dental caries and periodontal disease
The tongue surface can be a reservoir for tooth pathogens and periodontal pathogens. It can contribute to the recolonization of tooth surfaces. People with periodontal disease are more likely to have a thicker tongue coating and a microbial flora that produces more volatile sulphur compounds compared to those who have healthy periodontal tissues. Tongue cleaning might help to reduce halitosis, dental caries and periodontal disease.