Fetor hepaticus or Halitosis is a foul or disagreeable odor that emanates from the mouth. It is also termed bad breath, oral malodor, foul breath, or fetor ex oris.
Howe described Halitosis in 1874 until it did not become a clinical entity. Halitosis can be classified into genuine Halitosis, pseudo-halitosis, or halitophobia.
Genuine Halitosis can be physiological or pathological based on its origin. Based on the etiology, it is classified as Halitosis due to local factors and systemic factors of pathological and non-pathological origin, Halitosis due to drug administration, and xerostomia.
Over 600 species of microorganisms have been identified to have an association with Halitosis.
Some of them are Treponema denticola, Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia, Bacteroides loescheii, Enterobacteriaceae, Tannerella forsythia, Centipeda periodontii, Eikenella corrodens, Fusobacterium nucleatum, Micromonas micros, Campylobacter rectus, and Eubacterium species.
They act on sulfur-containing amino acids like methionine, cysteine, and methyl cysteine to produce volatile sulfur compounds (VSCs) like hydrogen sulfide, methyl mercaptan, and dimethyl sulfide  .
Halitosis is considered a significant social problem that affects an individual’s self-esteem. Bad breath is usually more of a nuisance rather than a serious medical condition. Most individuals with bad breath can treat and eliminate the disease on their own.
Additionally, they also seek dentists and physicians to help with chronic bad breath. The standard treatments like the prescription of mouthwashes provide only temporary relief. Understanding the etiology of Halitosis plays a significant role in eliminating it.
As Halitosis is primarily a result of microbial metabolism, ways to stop microbial growth can help to reduce malodor. The oral cavity provides an environment for the development of hundreds of microbial species with differing nutritional preferences.
Analyzing the presence of anaerobic Gramnegative proteolytic bacteria in the deep crevices of the tongue and hard and soft tissues of the oral cavity and treating them accordingly is essential.
In this review, the classification and characteristics of each odor are described (Table 1) so that the etiology of malodor can be better assessed for further management.
In addition, the available management methods of genuine Halitosis are presented (Table 2) so that it may be helpful for the oral health care providers to plan the treatment, educate, and counsel the patients who are burdened with Halitosis.
Etiological classification of Fetor hepaticus:
Halitosis can be classified into these categories:
- (1) Halitosis due to local factors of the pathological origin :
- The local factors include:
- Inadequate oral hygiene.
- Periodontal diseases.
- Extensive dental caries.
- Food impaction.
- Habits like smoking.
- Tobacco chewing can cause oral malodor.
Pathologies like Vincent’s disease, hairy tongue, and fissured tongue also are causes of Halitosis. The oral mucosa with some ulceration or necrotic tissue, healing extraction wounds, or any cyst or abscess draining into the oral cavity produces terrible breath.
Other conditions which can lead to Halitosis include chronic sinusitis, rhinitis, pharyngitis, oral, nasal, or tracheal tumors, cancrum oris, and syphilitic ulcers .
(2) Halitosis due to local factors of non-pathological origin:
Decreased salivary secretion in the night, which inhibits self-cleansing of the oral cavity and lack of movement of cheek and tongue during sleep, can lead to foul breath in the morning, commonly called ‘morning breath’ .
Dentures can produce a type of Halitosis referred to as ‘denture breath.’ This is more evident in patients wearing dentures made up of vulcanite than those wearing acrylic dentures.
This is because the porous nature of vulcanite dentures tends to trap more food debris leading to moral malodor .
Patients undergoing endodontic treatment can sometimes complain of bad breath due to leakage of eugenol and creosote placed in the tooth.
Children of 2 to 5 years of age may have a sweetish fetid odor emanating from the tonsillar crypts, which traps the food debris.
Men and women in their middle age suffer from severe morning breath. Improper maintenance of the dentures and saliva stagnation can lead to Halitosis in old patients  .
(3)Halitosis due to systemic factors of pathologic origin:
Uncontrolled diabetes mellitus, diabetic acidosis, or hyperglycemic coma can lead to a sweet, fruity odor in breath known as ‘ketone breath.
In patients with uremia or kidney failure, the odor of ammonia in-breath is present. Hepatic failure patients can have a sweetish feculent odor resembling a fresh corpse.
This is known as ‘fetor hepaticus'. A sweet acid odor is seen in patients with acute rheumatic fever, whereas a foul, putrefactive breath resembling odorous rotting meat suggests lung abscess or bronchiectasis.
Other systemic diseases causing Halitosis include toxemia, eosinophilic granuloma, polycythemia vera, anemia, acute and chronic scurvy, aplastic anemia, Letterer-Siwe disease, and Hand-SchiillerChristian disease, gastrointestinal disorders, gangrene of the lung and pulmonary tuberculosis- Patients under physical or mental stress tend to neglect oral hygiene that leads to Halitosis .
(4) Halitosis due to systemic factors of non-pathologic origin:
People who consume a vegetarian diet tend to produce less Halitosis than those who take excessive meat. This is because fewer waste products are made by degradation of vegetable proteins than meat.
Particular food like garlic, onion, leeks, and alcohol may produce malodor. People may also experience odor during hinger sensations due to putrefaction of pancreatic juices in the stomach called ‘hunger odor'.
(5) Halitosis due to systemic administration of drugs:
Drugs like isosorbide dinitrate, antineoplastic, antineoplastic agents, antihistamines, amphetamines, tranquilizers, diuretics, phenothiazines, and atropine are known to cause halitosis.
Atropine and antineoplastic drugs decrease the salivary flow, thereby decreasing the self-cleaning ability of the oral cavity leading to malodor. Patients who inhale amyl nitrate also produce an objectionable odor.
Phenothiazine occasionally causes black or white hairy tongue, which is difficult to clean and encourages the lodging of food debris. Dimethyl sulfoxide is prescribed for some patients suffering from muscle pain.
Though it is colorless and odorless, once metabolized, it is reduced to dimethyl sulfide, giving a distinct garlic-like odor .
(6) Fetor hepaticus due to xerostomia:
Apart from the above-mentioned drugs, salivary gland conditions like Sjogren’s syndrome, salivary gland aplasia, Mikulicz’s disease, radiation therapy exceeding 800 rads, macroglobulinemia with salivary gland involvement can lead to xerostomia.
Other conditions that may cause Halitosis include mouth breathing, high fever with dehydration, menopause, and emotional disturbances that can cause oral malodor .
Organoleptic measurements rank the intensity of odors are ranked by organoleptic measurements(Table 3). This is considered as the criterion standard for the size of malodor. In general, two separate judges evaluate the degree of Halitosis.
The intensity of malodor is marked either on a 5 point or 10 point scale. The intensity is based on the Rosenberg scale, which rates odor intensity and is as follows:
The best possible treatment is to identify the cause and eliminate it. So the treatment depends on the cause and often involves multiple modalities of treatment.
Masking agents like mint, toothpaste, mouth rinses, sprays, and chewing gums with pleasant flavors and smell can mask the malodor .
Mechanical reduction of microorganisms:
Bad breath caused due to fasting overnight or for long periods can cause bad breath, commonly referred to as ‘morning breath. The stagnation of food debris and epithelial cells over the tongue can cause bad breath.
When food is consumed, as it passes, it removes the coating over the tongue. Studies reveal that people who had solid breakfast showed 60% less VSCs one hour after breakfast.
A switch in diet can also help in reducing Halitosis. Intake of a high protein diet reduces the substrates for the production of VSCs, thereby reducing malodor. Preventing food intake that causes terrible breath like onion, garlic, prevention of drying of the oral cavity, proper hydration is the necessary steps to be followed.
Also, stimulation of salivary flow by using chewing gum can improve bad breath due to the presence of lysosomes in saliva that causes inhibition of bacterial growth.
Brushing the teeth, flossing, scraping of the tongue, and using toothpicks are few mechanical methods used to reduce malodor. They reduce the number of oral bacteria and their substrates, thereby reducing malodor .
All these methods can reduce the concentrations of VSCs for at least one hour. But in patients with high malodor, the limited duration of the effect makes the efficacy of these methods questionable .
Dentists and dental hygienists can provide professional oral health care. Usage of hand scalers, electric toothbrushes, interdental brushes, and cleaning of dentures can be carried out.
Complete mouth disinfection with scaling and root planning and usage of Chlorhexidine for patients with periodontitis is recommended. Elimination of habits like smoking and tobacco chewing can reduce Halitosis.
Chemical reduction of microorganisms:
Antimicrobial toothpaste and mouth rinses can reduce the number of microorganisms chemically, thereby reducing oral malodor.
Frequently used active ingredients in these products are Chlorhexidine, triclosan, essential oils, and cetylpyridinium chloride. Other effective chemical agents are allylpyrocatechol, Ltrifluoromethionine, and dehydroascorbic acid.
Active ingredients present in toothpaste, mouth rinses, lozenges, and other products such as metal ions (zinc, sodium, iminium, stannous, and magnesium and oxidizing agents are thought to interact with sulfur, neutralizing the VSCs and reduce malodor .
Combinations like Chlorhexidine and zinc, Cetylpyridinium chlide and zinc, Sodium and zinc, Iminium and zinc produce synergistic effects in reducing Halitosis. Full-strength oxidizing lozenges like dehydroascorbic acid were effective in lowering tongue malodor  .
Tonsillectomy may be indicated in patients in whom, even after proper management of tonsillitis, odiferous substances are still present in deep tonsillar crypts. Management of Helicobacter pylori that causes erosive and ulcerative changes in the gastrointestinal mucosa can improve halitosis .
Suspension of non-pathogenic Escherichia coli can be given to recolonize the intestinal tract with normal bacteria to suppress bacteria forming malodorous gases that can cause halitosis .
Halitosis is an unpleasant odor resulting from volatile sulfur compounds (VSCs) produced by the microbial putrefaction of food debris, cells, saliva, and blood.
It is essential to understand the pathogenesis, different types, and etiology of Halitosis to effectively treat it; often, oral malodor results from more than one factor. Hence, the treatment also involves multiple entities to achieve clinical success.
1. Akaji EA, Folaranmi N, Ashiwaju O. Halitosis: a review of the literature on its prevalence, impact and control. Oral Health Prev Dent. 2014 Jan 1; 12(4):297-304.
2. Howe JW. The Breath, and the Diseases which Give it a Fetid Odor: With Directions for Treatment. D. Appleton; 1883.
3. Yaegaki K, Coil JM. Examination, classification, and treatment of halitosis; clinical perspectives. Journal-Canadian Dental Association. 2000 May; 66(5):257-61.
4. Lu DP. Halitosis: an etiologic classification, a treatment approach, and prevention. Oral Surgery, Oral Medicine, Oral Pathology. 1982 Nov 1; 54(5):521-6.
5. Akaji EA, Folaranmi N, Ashiwaju O. Halitosis: a review of the literature on its prevalence, impact and control. Oral Health Prev Dent. 2014 Jan 1; 12(4):297-304.
6. Van Den Broek AM, Feenstra L, De Baat C. A review of the current literature on management of halitosis. Oral diseases. 2008 Jan 1; 14(1):30-9.
7. Lu DP. Halitosis: an etiologic classification, a treatment approach, and prevention. Oral Surgery, Oral Medicine, Oral Pathology. 1982 Nov 1; 54(5):521-6.
8. Burket, L. W.: Oral Medicine, Diagnosis and Treatment, ed. 7, Philadelphia, 1977, J. B. Lippincott Company, chaps, 7, 19.
9. Swenson HM. Halitosis: a brief review. Alumni bulletin-School of Dentistry, Indiana University. 1976 Dec:33-4.
10. Horowitz, A., and Folke, L.: Hydrogen Sulfide in the Gingival Environment, IADR Program and Abstracts, 1972, No. 39.
11. Lu DP. Halitosis: an etiologic classification, a treatment approach, and prevention. Oral Surgery, Oral Medicine, Oral Pathology. 1982 Nov 1; 54(5):521-6.
12. Kleinberg I, Westbay G. Salivary and metabolic factors involved in oral malodor formation. Journal of periodontology. 1992 Sep; 63(9):768-75.
13. Tonzetich J, Ng SK. Reduction of malodor by oral cleansing procedures. Oral Surgery, Oral Medicine, Oral Pathology. 1976 Aug 1; 42(2):172-81.
14. Edgar WM, Higham SM, Manning RH. Saliva stimulation and caries prevention. Advances in dental research. 1994 Jul; 8(2):239-45.
15. Coil JM, Yaegaki K, Matsuo T, Miyazaki H (2002). Treatment needs (TN) and practical remedies for halitosis. Int Dent J 52(Suppl. 3): 187-191.
16. Yaegaki K, Sanada K. Effects of a two-phase oil-water mouthwash on halitosis. Clinical preventive dentistry. 1992; 14(1):5-9.
17. Quirynen M, Mongardini C, van Steenberghe D. The effect of a 1stage full-mouth disinfection on oral malodor and microbial colonization of the tongue in periodontitis patients. A pilot study. Journal of periodontology. 1998 Mar; 69(3):374-82.
18. Brading MG, Cromwell VJ, Green AK, DeBrabander S, Beasley T, Marsh PD. The role of Triclosan in dentifrice formulations, with particular reference to a new 0.3% Triclosan calcium carbonate-based system. International dental journal. 2004 Oct 1; 54(S5):291-8.
19. Schmidt NF, Tarbet WJ. The effect of oral rinses on organoleptic mouth odor ratings and levels of volatile sulfur compounds. Oral Surgery, Oral Medicine, Oral Pathology. 1978 Jun 1; 45(6):87683.
20. Boulware RT, Southard GL. Sanguinarine in the control of volatile sulfur compounds in the mouth: a comparative study. The Compendium of continuing education in dentistry. 1984:S61.
21. Greenstein RB, Goldberg S, Marku-Cohen S, Sterer N, Rosenberg M. Reduction of oral malodor by oxidizing lozenges. Journal of periodontology. 1997 Dec; 68(12):1176-81.
22. Hoshi K, Yamano Y, Mitsunaga A, Shimizu S, Kagawa J, Ogiuchi H. Gastrointestinal diseases and halitosis: association of gastric Helicobacter pylori infection. International dental journal. 2002 Jun 1; 52(S5P1):207-11.
23. Henker J, Schuster F, Nissler K. Successful treatment of gutcaused halitosis with a suspension of living non-pathogenic Escherichia coli bacteria-a case report. European journal of pediatrics. 2001 Oct 1; 160(10):592-4.