Micro niches in the oral cavity of healthy individuals' harbor biofilm that may contain over 1000 different bacterial species. In the absence of active mechanical or chemical cleansing, biofilm accumulates, changes and matures, causing soft tissue inflammation, known as gingivitis. In some individuals and under certain conditions, inflammation progresses to periodontal disease, and the biofilm composition changes to a higher proportion of anaerobic Gram-negative bacteria with increased virulence and tissue-breakage capabilities. Aside of biofilm microorganisms, additional sources of VOCs in the oral cavity may include serum, gingival exudate, inflamed gum tissue, sores and lesions, pathologies associated with salivary glands, sinuses and nasal cavity, gastrointestinal reflux, interdental trapped food debris, and environmental pollutes. Hertel et al. has recently reported unique volatile profiles in the headspace of specific oral bacteria and fungi.