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Bad Breath

More than Just Embarrassing

By Dr. Ernest Newbrun


Oral Causes Of Bad Breath

Halitosis, oral malodor, bad breath, a rose by any other name — most common remedies are cover ups and often mask but do not get to the root of the problem. Though the causes of breath odor are not entirely understood, most unpleasant odors are known to arise from proteins trapped in the mouth that are processed by oral bacteria. There are over 600 types of bacteria found in the average mouth — several dozen of these can produce high levels of foul odors when incubated in the laboratory.

The most common location for mouth-related bad breath is the tongue. Large quantities of naturally-occurring bacteria are often found on the back of the tongue, where they are relatively undisturbed by normal activity. This part of the tongue is relatively dry and poorly cleansed, and bacterial populations can thrive on remnants of food deposits, dead skin cells and post-nasal drip. The convoluted microscopic structure of the tongue provides an ideal habitat for them, where they flourish under the continually-forming tongue coating.

When left on the tongue, these bacteria can yield the decaying smells of dead or dying animal or vegetable matter. Typically these odors are characterized by the “rotten egg” smell of volatile sulfur compounds (VSCs). VSCs have been shown to be statistically associated with oral malodor levels, and usually decrease following successful treatment.

There are other oral causes for halitosis, for instance the condition known as dry mouth (xerostomia) which is caused by mouth-breathing may contribute to bad breath, as can a variety of medications. Other parts of the mouth may contribute to the overall odor but are not as common as the back of the tongue. Inter-dental (between teeth) and sub-gingival (under the gums) niches, faulty dental work, food impaction areas, abscesses and unclean dentures are a few common examples. Studies have also correlated the amount of VSCs in mouth air with the extent of periodontal disease — the higher the VSCs in the breath the more likely the patient has gum disease.

Occasionally, treatment with antibiotics that suppress the normal oral flora can lead to a quite easily treatable yeast infection called candidiasis. This can be noticed from something as mild as a chronic cracking at the corner's of the mouth known as “perleche,” to a full whitish covering of the membranes of the mouth including the palate and throat which may have a somewhat sweet odor.

Another major source of bad breath is the nose. In this instance, the odor exiting the nostrils has a pungent odor that differs from the mouth. Nasal odor may be due to sinus infections, foreign bodies or pus from the tonsils — although the latter is generally considered a minor cause, contributing to only 3-5% of cases. Although approximately 5% of the population suffers from small bits of calcified matter in the tonsils (tonsilloliths) that smell extremely foul when released, these do not necessarily cause bad breath.

There are anecdotal claims that aging is associated with halitosis, but in the absence of disease, studies have found no increase. In hunger, especially starvation, as persons begin metabolizing or using their fats, the distinct acetone smell of ketones may appear on the breath. In addition, if no food is ingested, the tongue coating increases — which explains why more VSCs are detectable, the longer the interval between meals.

Medical Causes

There are a few systemic (general body) medical conditions that may cause halitosis, but these are extremely infrequent in the general population. Some of these conditions that can contribute to bad breath include:

  • Liver disease — causing “liver breath,” a rare type of bad breath caused by chronic liver failure
  • Lung infections — such as lower respiratory tract or bronchial infections
  • Diabetes — a disease caused by the lack of insulin, a hormone regulating sugar use
  • Kidney infections or failure
  • Cancer and other metabolic dysfunctions
  • Other diseases or abnormalities of normal function

However, people suffering from halitosis should not immediately conclude they suffer from these and other conditions just from the breath odor alone. These conditions are rare and may not display bad breath at all — in fact, patients will most likely show additional disease signs and symptoms more definitive or telling than breath odor.

Most researchers consider the stomach a very uncommon source for bad breath, except in belching. The esophagus (or gullet) is a closed and collapsed tube; as opposed to a simple burp, the continuous flow of gas or putrid substance from the stomach indicates a health problem like reflux, which will demonstrate more serious manifestations than just foul odor.

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