What is Bad Breath?

Normal breath is non-invasive and has been linked to scent of “blooming chestnuts”.  On the other hand, bad breath is unpleasant and offensive, a “sour, bitter, metallic” taste and can vary with the cause and can also be sulfurous.  The main components of bad breath are:  methyl disulfide, cadaverine and putrescine.  Bacteria is the most common cause of oral malodor.  Anaerobic bacteria are generally implicated and include: Porphyromonas gingivatis, treponema denticola, Prevotella species, Fusibacterium species, Peptostreptococcus species, and Capnocytophagia.  Fungus is also involved and produces a very unpleasant and somewhat sour odor.  When the mouth is dry, anaerobic bacteria are not flushed away and increase in concentration.  This leads to an increase in volatility, stronger malodor, and a dry pasty taste.  The reduction of flushing with saliva also leads to an increase in nutrients that are available to the bacteria.  Tongue saliva becomes more basic and this environment promotes the growth of even more anaerobes.  Breath odor and bad taste continue to increase.


To form an odor, the bacteria require a substrate provided by amino acids.  The substrates are metabolized to form volatile substances.  Substrates are most commonly cysteine, cysteine methionine, trptophan, ornithine, and arginine.  The bacterial metabolic by products are hydrogen sulfide, methyl mercaptan, acetic acid, proprionic acid, putrescine and cadaverine.

Methyl Mercaptan:

Methyl Mercaptan is the most potent in oral malodor and is associated with periodontitis.  The best indicator for presence is bleeding on probing.  It can effectively penetrate oral mucosa through crevicular membranes.  Some of the celluar effects are inhibition of protein synthesis, degradation of collagen, alteration of cell shape and depression of white blood cell formation.

Hydrogen Sulfide:

Most Common. It is irritating to mucous membranes and to the respiratory tract. It can affect the nervous system and respiratory of present in air in substantial amounts so it possibly can account for taste and respiratory irritation in the amounts found in bad breath.


  1. Food Odors: garlic, onions, dairy, meats, fats, coffee, alcohol
  2. Hunger Odor: unpleasant; results from metabolic breakdown of proteins and fats when there is insufficient carbohydrate in the diet. Can also happen with strenuous exercise and fasting. Fruity odor of ketones.
  3. Smoker’s Breath: starving the mouth of oxygen and promoting overgrowth of anaerobic bacteria
  4. Women’s Menstrual Breath: mousy odor
  5. Medications: causes dryness
  6. Dental Conditions: periodontitis, gingivitis, caries, crowns with poor margins, overhangs in restorations
  7. Systemic Conditions: diabetes, renal failure, reflux, hiatus hernia
  8. Sinus, Throat, Tonsil Infections, Post Nasal Drip
  9. Carcinomas, Xerostomia, Candidiasis
  10. Bacteria: increase concentration, increase VSC production, increased volatility, anaerobic
  11. Mouth Breathing: most sulfur products produced

Tongue Coating

The tongue is composed of cellular debris, blood cells and bacteria.  Variation in mouth odor is related to the amount of coating that is present.  The amount of coating increases as mouth odor increases, but removal of the coating and flushing will decrease odors by 50%.  The pH on the tongue changes to a neutral or alkaline pH and this favors malodor production.  Increased with stress levels.  Tongue cleaning is an essential component of oral malodor treatment.

Effects of Stress

  • Life dissatisfaction-respiratory illness
  • Personal failure-respiratory illness
  • Emotional distress anxiety-herpes simplex, mononucleosis
  • ANUG Lack of control-periodontal disease
  • High immune reactivity and high stress-high rate of disease
  • High immune reactivity and low stress-moderate rate of disease
  • Low immune reactivity and high stress-moderate rate of disease
  • Low immune reactivity and low stress-low rate of disease

Treatment and Assessment of Halitosis


An effective measuring tool, electrochemical sensor, and is efficient in assessing the amount of hydrogen sulfide that is present.  It measures the ppb of volatile sulfur compounds (VSC).  It does not measure Mercaptan well and will be compounded by alcohol, amount of saliva, and air pressure.


Exhaling and smelling, smelling saliva, smelling a partially dry wrist

Brushing and Cleaning the Tongue:

Tongue cleaners (decreases to a low level for several hours), dental debridement and prophylaxis (decreases to a low level for several hours), toothbrush with toothpaste (returns within 2 hours)

Antimicrobial Rinses:

In general, 3-4 hour protection.  Research indicates that CHX and zinc ion are very effective.

  1. Chlorhexidine (CHX)- longer time of protection and can last up to 24 hours if bacterial loading is moderate.  Can come in strengths of 0.12% and 0.2% and come in combination with alcohol or zinc gluconate.  Some disadvantages are:  taste depression and staining.  Also available in non-alcohol rinse.  70% reduction of mouth odor and effectiveness depends on microbial load. (Available at our office)
  2. Breath Rx- Combination of zinc gluconate and cetylperidium chloride (CPC) along with some eucalyptus and thymol.  It can be effective for 3-4 hours and may be longer if bacterial loading is moderate.  PerioWorks- Has a rinse that contains 0.2% zinc chloride.
  3. Peroxide Rinses- Such as Peroxyl are effective, but can only be used for short periods of time.  Baking Soda- These products also reduce odors well and have a time effect of about 3 hours ( 40% reduction).
  4. Herbal Rinses-  Such as tooth and gum are a good alternative for those who wish a natural treatment.  The effect is about 3-4 hours for moderate cases.
  5. Chlorine Dioxide-  Rowpar products, Oxyfresh, Oxygene, Therabreath, Profresh.  Disadvantages are the lack of research to show efficacy as well as studies on long tem effects.
  6. Biotene- Very effective in reducing the dry mouth conditions and can be combined with another antimicrobial for comfort and reduction of bad breath
  7. TriOral-  New rinse popular in the US and works on the principal of active zinc ions changing bacterial metabolic processes from protein degradation to carbohydrate metabolism.  Since carbohydrate metabolism produces odor free by products, there is a substantial relief odor.

Eating/Drinking Certain Foods:

Eating foods like celery and carrots can stimulate salivary flow.

Drinking plenty of water is needed to produce enough saliva.

Chewing Gum:

Sugar Free Gum or gum with Xylitol helps generate saliva.  This should only be done for short periods of time as chewing over long periods of time may encourage TMJ problems.

Successful treatment is usually a combination of good oral hygiene along with the use of an antimicrobial mouthwash.  A problem to watch for is the loss of effect as the bacteria rebound or become resistant to the antimicrobial compound. 

  • What To Do
  • Measure odors
  • Locate Source
  • Analyze Presence of Microbes
  • Assess Nutrition
  • Treat Condition
  • Reassess Treatment

This is a common problem that is easily eliminated in most cases.

Causes and Cures:

Certain foods such as onions and garlic can cause halitosis. Trapped in the lungs, the odor is mixed with the expelled air and may linger for quite some time. A temporary problem which can be improved with mouthwash.

Irregular oral hygiene, including absence of daily brushing and flossing will result in bad breath. When food and bacteria remains in the mouth, it decays. This process results in bad breath and can be eliminated with regular daily plaque and food removal.

Periodontal disease (gum disease) is a serious bacterial infection in which poisons are released into the gum tissues and bone. This infection results in inflammation which releases odors resulting in bad breath. Treatment of the infection along with regular bacteria removal, both professionally and at home, will help eliminate halitosis of this origin.

Xerostomia (dry mouth) which is a reduction of saliva can contribute to halitosis. A reduction in saliva may result from faulty salivary glands, medications, or mouth breathing. This reduces the natural cleansing of odor causing bacteria. Treatment may include frequent water and use of products which stimulate saliva. 

Regular tobacco use can result in mouth malodor. Smoking results in a greater risk of developing bad breath, gum disease, and more seriously, oral cancer. Cessation of smoking is indicated.

Systematic diseases can also cause halitosis. Upper respiratory infections, diabetes, and gastrointestinal disease can all cause bad breath. Treatment may include specific oral care such as: tongue cleaning, use of prescription strength antibacterial, or fluoride mouth rinses.