The production of bad breath (oral malodor, halitosis) is multi-factorial and may involve both oral and non-oral sources.1,2 Non-oral sources of breath odor would include pathologic conditions outside the mouth such as nasal, paranasal, laryngeal regions, the pulmonary or upper digestive tract (non-blood-borne extra-oral halitosis). An example of an extra-oral, blood-borne odor is cirrhosis of the liver. In this example, the odor is emitted via the lungs but its origin is from the liver. Conditions such as type 2 diabetes, kidney disorders, and pulmonary disease may also contribute to offensive breath odor. Some medications, especially those that reduce salivary flow such as antidepressants, antipsychotics, narcotics, decongestants, antihistamines, and antihypertensives can exacerbate breath odor. These non-
oral sources of breath odor have been well reviewed in the literature.2,3,4 However, while systemic conditions and medications can contribute to breath problems, most authorities seem to agree the majority of bad breath originates in the oral cavity.

Bacterial putrefaction of proteins by gram-negative and some gram-positive anaerobic bacteria,5,6,7 particularly those residing on the posterior dorsum of the tongue, utilize sulfur containing amino acids, primarily cysteine and methionine,8,9,10 to produce volatile sulfur compounds (VSCs).11 Although other organic components (e.g., organic acids, indole/skatole, putrescine, cadaverine) may be involved in the production of halitosis,12 hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl sulfide [(CH3)2S] have been identified as the predominate VSCs responsible for oral malodor.9,13,14 While the tongue is considered the primary source of VSC production, other dental problems can generate these offensive gases.

Dental conditions such as gingivitis, periodontal disease, gross carious lesions, and poor oral hygiene have been shown to contribute to bad breath.5,10,15-19 However, when dental disease is the source of oral malodor, treatment of the condition will often eliminate the problem.5,10,17,19 The tonsils have also been reported as a possible source of halitosis.20 Likewise, transient breath problems from eating spicy foods, smoking, and drinking certain beverages will most often disappear shortly after their use is discontinued.1,21 However, while eliminating these sources can successfully treat the majority of patients who suffer from bad breath, some individuals continue to have chronic breath problems.

It has been estimated that up to 25% of the population suffer from bad breath on a regular basis in spite of having good physical and oral health and after the elimination of offensive foods and beverages.22,23,24 It is these patients that most need our expertise. While there are many new products and emerging information regarding the treatment of oral malodor, the dental professional also needs to feel comfortable sharing this information and these products with their patients.