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Bad breath or halitosis is one of the major oral health problems as it can be found in 30-40% of the population. The condition can be chronic and sometimes does not respond to routine tooth brushing or mouth washing.

Many chemicals cause the smell in bad breath including hydrogen sulphide, methyl mercaptan and dimethyl sulfide. These chemicals are produced mainly from the anaerobic breakdown of proteins by intraoral bacteria to produce detectable foul gases. These proteins are the remains of food debris, dental plague and inflammatory cells in blood. Bad breath can also caused by postnasal drip. This is mucus that trickles down the back of the throat in patients with allergies or a sinus infection.


There are

  • Intra-oral causes
  • major causes of bad breath;
Intra-oral causes
  • Tooth decay and impacted wisdom teeth
  • Gum diseases
  • Intra-oral wounds such as apthous ulcers or extraction/ infected surgical/ cancer wounds
  • faulty dental work, food-impaction areas in-between the teeth, abscesses and unclean dentures.
  • Malposed teeth or wearing brazes • Bacteria on the back of the tongue (white coating of the tongue)
  • Anything that dries the mouth, such as medications and alcohol, makes bad breath worse

Bacteria on the back of the tongue are one of the commonest causes of bad breath. Food particles, postnasal drip and inflammatory cells from gum diseases build up at the back of the tongue, providing a breeding ground for bacteria. These bacteria produce many foul-smelling chemicals such as Methyl mercaptan. From research data, patients who suffer from dry mouth had accumulated chemicals 6 times higher than healthy controls

Extra-oral causes

Post nasal drip or nasal discharge from sinuses into the back of throat can cause mouth odor. Discharge from other sources such as chronic inflammation of the respiratory system; sinusitis, tonsillitis, bronchial and lung infections can be a source of bad breath
Gastrointestinal problems such as esophagitis, gastritis and GERD may cause bad breath. The reflux from stomach could alter the respiratory lining and consequently cause post nasal drip. Other illnesses, such as some cancers and certain metabolic disorders, can cause a distinctive breath odor .
Foods that you eat and drink will affect your breath. Normally most of the smell of foods will disappear after they are digested. However, some foods and beverages may cause bad breath if taken intake frequently includes onions, garlic, certain spices, coffee and alcohol beverages.
There are numerous causes for bad breath but 80-90 % of them comes from inside the mouth. If you are one of those who suffer from this problem, you can contact us at The Fresh Breath Clinic, Vejthani hospital

Periodontal disease caused by the accumulation of dental plaque and calculus. These bacteria found in dental plaque produce many foul- smelling chemicals such as Methyl mercaptan.

Patient suffers from dry mouth makes bad breath worse by accumulating more of the sulfur compounds


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