Bad breath (which is also known as halitosis) is something the vast majority of people around the world are familiar with. We have all likely encountered somebody with halitosis in our lives and many of the people reading this might even suffer from it. There are a range of causes of halitosis, including eating or drinking strong-smelling food and drinks, gum disease or problems with the teeth, smoking and particular medical conditions, such as tonsillitis. The best method for preventing halitosis is to perform adequate oral care, such as brushing your teeth and gums regularly, cleaning the tongue, flossing, using antibacterial mouthwash, and having regular dental check-ups. While much of this can be considered common knowledge, it is perhaps less well known that halitosis is subdivided into intraoral and extraoral halitosis, depending on the place where it originates. Dr Masato Hotta, from the Graduate School of Dentistry, Asahi University, is interested in exploring this topic in more detail. He explains that approximately 90 per cent of halitosis is intraoral, where it originates from within the oral cavity and is caused by volatile sulphur compounds (VSCs), such as hydrogen sulfide (H2S), methyl mercaptan and dimethyl sulfide. ‘These VSCs are brought about through the bacterial putrefaction of food debris, cells, saliva and blood,’ Hotta clarifies. ‘VSCs are malodorous materials and, in addition to causing bad breath, can cause secondary tooth decay, the discoloration of teeth and dental prosthetic alloys, and periodontal disease.’ While brushing and flossing are effective ways of removing biofilm and bacteria, they often have little effect on VSCs. Thus, finding a means of removing them from a patient’s mouth - and alleviating bad breath - would be considered a significant breakthrough for patients with halitosis.