Background Oral malodor, also known as halitosis or bad breath, is a common problem worldwide and is associated with social embarrassment, anxiety and psychological depression. 1 Therefore, oral malodor has a negative impact on quality of life. Oral malodor is reported to be the third most frequent reason for people to seek dental care, behind dental caries and periodontal diseases. 2 The prevalence of oral malodor varies by country. Previous research has reported that about 30% to 50% of the population present with the oral malodor. 3-5 Oral malodor can be detected by the organoleptic test, that is regarded as a gold standard. 1 Alternatively, it can be examined by using sulfide monitoring equipment such as the Halimeter®, Breathtron®, Oral Chroma® and Gas chromatography. 6 Many factors influence oral malodor including poor oral hygiene, tongue coating, periodontal diseases, low salivary flow, advanced caries, oral mucosal ulceration, ill-fitting restorations and systemic diseases like upper respiratory tract diseases, stomach problems, liver diseases and kidney diseases. 7 Among the causative conditions, more than 90% of the oral malodor originates from the oral cavity and the remainder is due to systemic diseases. The main chemical compounds of oral malodor are volatile sulfur compounds (VSCs). 8-10 Any area in the oral cavity where microorganisms, plaque and oral debris accumulate can produce VSCs. VSCs are mainly generated through putrefactive activities of anaerobic bacteria in the oral cavity. These bacteria are commonly found in the dorsum surface of the tongue and most of them are the same bacteria as those associated with gingivitis and periodontitis. 1,9,11 The tongue forms a distinct environment for the accumulation of microorganisms, desquamated epithelium cells, and food debris due to its specific anatomical structure. 12