This is accomplished by subgingival scaling and root planing and irrigation with an antibiotic mouth rinse. The bacteria that cause gingivitis and periodontal disease (periodontopathogens) are invariably gram negative and capable of producing VSC. Methyl mercaptan is known to be the greatest contributing VSC in halitosis that is caused by periodontal disease and gingivitis. The level of VSC on breath has been shown to positively correlate with the depth of periodontal pocketing, the number of pockets, and whether the pockets bleed when examined with a dental probe. Indeed, VSC may themselves have been shown to contribute to the inflammation and tissue damage that is characteristic of periodontal disease. However, not all patients with periodontal disease have halitosis, and not all patients with halitosis have periodontal disease. Although patients with periodontal disease are more likely to develop halitosis than the general population, the halitosis symptom was shown to be more strongly associated with degree of tongue coating than with the severity of periodontal disease. Another possible symptom of periodontal disease is a bad taste, which does not necessarily accompany a malodour that is detectable by others. Other causes
Other less common reported causes from within the mouth include:
Deep carious lesions (dental decay) – which cause localized food impaction and stagnation
Recent dental extraction sockets – fill with blood clot, and provide an ideal habitat for bacterial proliferation
Interdental food packing – (food getting pushed down between teeth) - this can be caused by missing teeth, tilted, spaced or crowded teeth, or poorly contoured approximal dental fillings.
The intensity of bad breath may differ during the day, due to eating certain foods (such as garlic, onions, meat, fish, and cheese), smoking, and alcohol consumption. Since the mouth is exposed to less oxygen and is inactive during the night, the odour is usually worse upon awakening ("morning breath"). Bad breath may be transient, often disappearing following eating, drinking, tooth brushing, flossing, or rinsing with specialized mouthwash. Bad breath may also be persistent (chronic bad breath), which affects some 25% of the population in varying degrees. Tongue
The most common location for mouth-related halitosis is the tongue. Tongue bacteria produce malodourous compounds and fatty acids, and account for 80 to 90% of all cases of mouth-related bad breath. Large quantities of naturally occurring bacteria are often found on the posterior dorsum of the tongue, where they are relatively undisturbed by normal activity. This part of the tongue is relatively dry and poorly cleansed, and the convoluted microbial structure of the tongue dorsum provides an ideal habitat for anaerobic bacteria, which flourish under a continually-forming tongue coating of food debris, dead epithelial cells, postnasal drip and overlying bacteria, living and dead. When left on the tongue, the anaerobic respiration of such bacteria can yield either the putrescent smell of indole, skatole, polyamines, or the "rotten egg" smell of volatile sulfur compounds (VSCs) such as hydrogen sulfide, methyl mercaptan, allyl methyl sulfide, and dimethyl sulfide. The presence of halitosis-producing bacteria on the back of the tongue is not to be confused with tongue coating.