CKS found a lack of good quality evidence on treatments for halitosis.

• Apart from two Cochrane systematic reviews on mouthrinses and tongue scraping (which found poor evidence for their use), no systematic reviews or meta-analyses were identified for other treatments such as toothpastes, interdental aids (such as dental floss), chewing gums, and mouth sprays.
• Most trials were generally small with less than 40 participants in each treatment arm and were short term (for example, a single treatment or treatment for 1–2 days) [Loesche and Kazor, 2002; Quirynen et al, 2002b]. Few trials were of double-blind design. Most were sponsored by industry.
• In addition, outcome measurements were generally based on secondary outcomes.
• Most studies utilized portable sulphide monitors (such as the Halimeter^®) to measure the level of volatile sulphur compounds (VSCs) as a measure of oral malodour.
• Given that other compounds are also responsible for oral malodour, VSC measurement alone can provide an inaccurate assessment of the source and intensity of the malodours [Messadi and Younai, 2003; Porter and Scully, 2006; Hughes and McNab, 2008; Scully and Greenman, 2008; Van den Velde et al, 2009]. In addition, it explains why oral malodour is sometimes detected by the examiner (subjective organoleptic assessment), but the VSC levels are in the low range [Loesche and Kazor, 2002].
• Other methods (such as gas chromatography) are regarded as more accurate but are not routinely used in studies.