Probably a misdiagnosed systemic health, CA, oral ph, microbiota, many acidic foods, find out more.

Have they been tested with a Halimeter that measures volatile sulfur compounds (VSC) that are responsible for oral malodor?  Are they cleaning their tongue?  Post nasal drip or sinus problems?  High protein diet (ketones)? Medications that could cause it? Dry mouth?

Try chlorine dioxide mouthrinses if it is from VSC. 

check the tonsils for infection or Tonsilolith. Tonsilolith smells very bad. Better to have a ENT examination also for sinusitis, Tonsilolith, CA pharynx etc

Thank you all for your response and great answers, providing that nothing of mentioned is present and every thing is fine, could it be type of  the normal flora of the oral cavity  in some individuals causing that, if so what is the treatment specially if the patient if suffering a lot from what he got

Has halitosis been professionally diagnosed?  Halitophobia is a possibility if not as mentioned above.

http://www.nature.com/ijos/journal/v4/n2/full/ijos201239a.html

Psychogenic halitosis is becoming the most common presentation of halitosis in the Dental clinic. No diagnosis of psychogenic halitosis(halitophobia) should be made until you have ruled out both local and systemic causes of halitosis.

Check for Cryptic tonsils: these pockets in the tonsils accumulate food and other debris and cause bad breath.

Thank you Dr Okoh, could you please mention what does Halitophobia mean? does it mean it is not existed the patient just have a phobia of halitosis? and thanks again

thank you Mr. Zuluaga, i liked the answer  yes i think that is very possible with special type of food

Thank you Dr Donna, No, not diagnosed professionally but he always warned and strongly by his family and friends, could you please mention how the professional diagnosis of halitosis will be done??

email me at [email protected] and I will send you my presentation on this topic.

Smoking could cause it, as well as the causes mentioned from our collegue. Anaerobic microbial agents are the most common cause of malodor.

We suggest the following treatment with very successful results.

Metronidazole for 10 days 500mgr every 12 hours followed by Unisept buccal drops (O2 ) rinses for 20-30 days. Use of tongue cleanser and ofcourse excellent oral hyegene

Thank you Dr. Eleana, am going to follow your treatment regime with pleasure and let you know

Recurring sinus infections and base of the tongue tonsils harboring sulfur containing bacteria. Both conditions difficult to diagnosis from just a dental perspective. Would involve other medical professionals with this case to determine exact source of the odor. Also, rule out any history of bulimia or GERD

Please send me an e mail on [email protected]. Before, I answer your question, I would like to know certain things about the patient.

Dear Mr. Syed, Thank you for our response i would rather like to share our colleagues in this group all the discussion and answers please let the conversation be public nd dont hesitate to ask any question bout the case, you will get my answers on this page with pleasure

Lots of things. Please see my paper on this. It is on pubmed.

http://www.ncbi.nlm.nih.gov/pubmed/24624640

I have also attached it here for your convenience!

Thanks!

oral or extraoral halitosis (difference when somebody closes nose and exhales through mouth or closes mouth and exhales through nose)

oral-coated tongue and periodontal disease

extraoral-tonsilitis, tonsiloliths, lung diseases (pneumonia, abscessus and cancer), meds (disulfiram, phenotiazines, amphetamines, nitrates, chlor hidrate, dimetil sulphaxide) Helycobacter pylori infection, rinitis, sinusitis, nasopharyngeal absessus, faringitisom, bronchitis. Diabetes melitus, liver and kidney cirrhosis, hiatal hernia. Metabolic disturbance -trimethilaminuria and leukemia.

Thank you Dr. Solomon i appreciate very nice of you 

Many Thanks Dr. Vanja seems there are lot of systemic backgrounds behind oral mal-odour, I think appropriate and final diagnosis of the cause is a team collaboration to find out the exact source of halitosis thus its treatment

Have you assessed their malodor organoleptically or using a Halimeter? If you did and whether found presence or absence of odor while they had good oral hygiene without any other systemic problems, the ideal next step for you will be to carry out a cysteine challenge test to ascertain whether the odor originate from oral or non-oral sources.

Thank you Dr. Yes Don Codipilly exactly the case is a good orl hygiene no obvious local or systemic causes. and please what is a cysteine challenge test you mentioned in your answer?? I think you have a publication about the cysteine challenge test

Dr. Zardawi,

Cystein challenge test (CCT) is based on the ability of odorgenic bacteria in the mouth to rapidly use cysteine to produce hydrogen sulfide (HS). In a clinical situation the patient rinses his/her mouth with a cysteine solution for 30 seconds, spit out and record Halimeter readings at 2 minute intervals for 20 minutes (for more information see publications). What you will observe is a peak HS level reached around 2- 4 minutes and gradually falling back to baseline level in about 20 minutes. The peak HS value is an indication of the level of malodor producing potential which in turn is related to the level of odorgenic bacterial population in the mouth. I have observed that some subjects with apparently good oral hygiene show higher HS peak values. Most such subjects showed hidden areas that could harbor anaerobic bacteria such as overhanging restorations, malocclusions, malaigned teeth, loose tooth contact points, hidden cavitations, deep tongue papillae etc.

anaerobic bacterial infection.

Big question is 'can you smell anything'?

If you can't it may be psychological.

Next try tongue cleaning and chlorhexidine mouthwash.

System causes are very rare.

Very good training module available on halitosis from British Medical Journal website.

Thanks Patrick Magennis for your response. However, an online publication affirms that the examiner should

1. have "normal" sense of smell, is required to

2. Refrain from drinking tea, coffee, or juice

3. Refrain from smoking and using scented cosmetics

There are obvious problems with the organoleptic method including;

1.Low objectivity

2. Poor reproducibility

Therefore, simply dismissing the case as "psychological" because I can't smell anything appears overly simplistic. I think more details are obviously needed.

Thanks Patrick!

I did not say "dismiss the case as psychological", but rather consider this problem as one of your diagnoses (which no-one else had done thus far). Someone with any type of monosymptomatic hyperchondriacal neurosis have just as much of a problem as someone with deep smelly pockets. They just need different care.

If they are saying, and they often do, that people treat them differently because of the social impact of their halitosis, and no-one  else can smell it......

from BMJ Learning

http://learning.bmj.com/learning/home.html

Key Points

Halitosis is common and can affect people of all ages

In about 85% of patients with persistent pathological halitosis, the odour originates from the mouth

Respiratory, gastrointestinal, and metabolic diseases account for the remaining 15% of patients

Malignancy of the mouth and the upper respiratory and gastrointestinal tracts is a rare cause of halitosis

A subjective self reported bad breath, in the absence of any objective halitosis, can be an expression of a monosymptomatic hypochondriacal psychosis

Table 3: Common extraoral causes of halitosis

Nasal or sinusal disorders

Sinusitis

Foreign bodies in the nose

Cleft palate

Malignancy

Pharyngeal Tonsillitis

Tonsilloliths*

Malignancy

(*Controversial, perhaps depending on the extent to which they are exposed to the air passing over the tonsillar crypts)

Upper gastrointestinal tract

Oesophageal diverticulum*

Gastro-oesophageal reflux disease*

Malignancy* (*extremely rare)

Respiratory system Infections

Bronchiectasis

Lung abscess

Malignancy

Systemic disorders

Acetone-like smell in uncontrolled diabetes mellitus (rare in modern society)

Uraemic breath in renal failure

Foetor hepaticus in liver disease

Trimethylaminuria (fish odour syndrome)*

Hypermethioninaemia

(*In fish odour syndrome, others may or may not be able to verify the oral odour, although the subjects are sometimes adamant that this is the case)

The expertise of a Dentist should only be, to exclude all oral causes as responsible for the perceived oral odor. Once that task is complete, the patient should be referred to an appropriate medical specialist.

After all possible local and systemic causes have been considered you should consider psychogenic halitosis.

Dear Don Codipilly, I agree, just that we should not forget that 90% of causes are oral. We should be careful at really "confirming" possible causes before the exclusion process starts. Patients again are often quick to jump to the conclusion that their halitosis has medical roots even in the face of obvious oral causes. 

Attention to details I think holds the key. With many oral/dental problems, being a good dentist helps you to get by. Unfortunately, with halitosis, there is no substitute for excellent dentistry!

Cheers!

Change of strains or numbers of bacteria colonies and their metabolic products in the oral cavity could cause the halitosis problem with no obvious local or systemic cause.

Treatment with metronidazole for 10 days 500mgr x2 per day and then unisept (oral peroxide) drops twice /day for one month to stabilize the result is what we use with excellent results from the third day

If all the necessary investigations have be carried out and there's still no obvious cause for the halitosis, then it can be concluded that the patient is suffering from psychogenic halitosis (halitophobia).

primarily halitosis is caused by oral disturbance such as periodontal disease or coated tongue, and if not systemic causes might be various: sinusitis, tonsiloliths, pneumonia or even lung cancer, then gastrointestinal diseases such as H.pylori infection (smells usually like sewage), then medications (for exampel disulphiram for alcoholics), and inherited syndromes which are rare. First you have to smell whether patient has halitosis at all then distinguish oral and extraoral halitosis. Treatment is according to the cause.

si despues de un examen bucal minucioso no se corrabora causas dentales de la halitosis hay que dirigir la busqueda hacia causas sistemicas entre las mas comunes estan , diberticulos en el trayecto esofagico asi como problemas de reflujo gastrico, sinusitis maxilar y estres, penfigo vulgar.

Decomposition of food remnants and exfoliated epithelial cells as well as saliva stagnation are the factors which contribute to the occurrence of physiological halitosis leading to the bacterial accumulation on the dorsal surface of the tongue which is clinically manifested by the tongue coating.