Is there any connection between periodontitis and bad breath?

Bad breath has always been a health problem that is neither big nor small, but it is indeed annoying. Therefore, how to reduce or even eliminate bad breath is the most concerned issue for the public. However, everything must be traced back to the source in order to be fundamentally solved. Therefore, figuring out where bad breath comes from is the first issue.
It is known that the sources of bad breath are actually very complex, but in general, most of them (nine out of ten) are related to oral health problems. Bad breath usually comes from the bacterial habitats in the mouth, such as the back of the tongue, periodontal tissue sites (gingival sulcus, periodontal pockets and interdental spaces), poor restorations, deep caries and improperly maintained dentures. The bacteria gathered in these sites can degrade sulfur-containing and non-sulfur amino acids (derived from proteins in shed human epithelial cells and leukocyte fragments, or present in dental plaque, saliva, blood and tongue coating), and thus produce substances such as volatile sulfide (VSC) (the direct cause of bad breath). These bacteria are often Gram-negative bacteria associated with periodontitis. In addition, patients with periodontitis often complain of bad breath. This makes people wonder: Is there a relationship between bad breath and periodontitis? What is the relationship?

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1. “Related” Theory

The evidence supporting the relationship between halitosis and periodontitis is as follows: ① halitosis is mainly caused by Gram-negative anaerobic bacteria, which coincides with the cause of periodontitis; ② the production of hydrogen sulfide (one of the VSCs) is related to periodontal pocket inflammation, and the concentration of hydrogen sulfide is highest in the deepest part of the periodontal pocket; ③ low concentrations of VSCs will damage the gingival tissue in a short period of time, and increased production will accelerate the progression of periodontitis; ④ salivary sediments (including epithelial cells, leukocytes, etc.) will produce VSCs after the decay process. Compared with non-periodontitis patients, the total number and proportion of damaged epithelial cells and leukocytes in the saliva of periodontitis patients are larger; ⑤ compared with non-periodontitis patients, periodontitis patients have thicker tongue coating, which is an important source of halitosis.

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2. “Irrelevant” Theory

The evidence supporting the fact that bad breath is not related to periodontitis is as follows: ① People with healthy periodontal tissues can also have bad breath; ② Tongue coating is the main source of bad breath; ③ The periodontal pocket is a nearly closed environment with a very small surface area. Even if VSC is produced, only a small part of it can enter the oral cavity; ④ Brushing the tongue coating can significantly reduce the VSC level.

Although the relationship between bad breath and periodontitis is still unclear, it is certain that thick tongue coating is the main source of bad breath. Although periodontitis seems to be less important, it is also related. After all, patients with periodontitis tend to have thicker tongue coating.