INTRODUCTION:

Halitosis, fetor oris, oral malodor or bad breath are the general terms used to describe unpleasant breath emitted from a person’s mouth regardless of whether the odorous substances in the breath originate from oral or non-oral sources. Halitosis is an oral health condition characterized by consistently emanating odorous breath and may be caused by several agents including certain foods, poor oral health care, improper cleaning of dentures, decreased salivary flow rate, tobacco products or a medical condition. In 90% of cases, the causes of halitosis are located in the mouth and can be attributed to deep carious lesions, periodontal disease, oral infections, periimplant disease, pericoronitis, mucosal ulcerations, impacted food or debris, factors causing decreased salivary flow rate and, mainly, tongue coating (1).

The tongue is a major site of oral malodor production, while periodontal disease and other factors seem to be only a fraction of the overall problem and some systemic factors like tonsils, bronchiectasis, lung abscesses and gastrointestinal pathology (2). Halitosis may be an important factor in social communication and, therefore, may be the origin of concern not only for a possible health condition but also for frequent psychological alterations leading to social and personal isolation (3). About 50% of the population complains of malodor which leads to social embarrassment. The mouth air of chronic malodor sufferers is tainted with compounds such as hydrogen sulfide, methyl mercaptan and organic acids, which produce a stream of foul air that is gravely offensive to the people in their vicinity. Sufferers often make desperate attempts to mask their oral malodor with mints and chewing gum, compulsive brushing, and repeatedly rinsing with mouthwashes (4).

ETIOLOGY:

Halitosis is caused by oral and systemic effects. 85% of halitosis is caused by oral cavity, conditions like tongue coating, gingivitis, periodontitis, stomatitis, intra-oral neoplasia and xerostomia. The other causes are systemic effects like tonsilloliths, bronchiectasis, lung abscess (5) and some gastrointestinal pathologies (6).

ETIOPATHOGENESIS:

The oral microorganisms most likely to cause oral malodor are Gram-negative bacteria species including Treponema denticola, Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia, Bacteroidesloescheii, Enterobacteriaceae, Tannerella forsythensis, Centipedaperiodontii, Eikenellacorrodens, Fusobacteriumnucleatum (7). The bacterial interactions are most likely to occur in the gingival crevices and periodontal pockets, but oral malodor can also arise from the posterior dorsal tongue. As a consequence of its large and papillary surface area, the dorsum of the tongue can retain large amounts of desquamated cells, leucocytes, and microorganisms. Donaldson et al, examining the microflora present on the tongue dorsum of subjects with and without halitosis, observed that the predominant species in test and control groups were Veillonella sp. and Prevotella sp. Greater species diversity was found in the halitosis samples com- pared with controls. The halitosis samples contained an increased incidence of unidentifiable Gram-negative rods, Gram-positive rods and Gram-negative coccobacilli (8). The sample shows increased number of species which results of complex interactions between several bacterial species. Microbial degradation in the oral cavity is the main cause of oral malodour. Due to this process, volatile sulphur compounds (VSCs) are formed. The most important VSCs involved in halitosis are hydrogen sulphide (H2S), methyl mercaptan (CH3SH) and dimethyl sulphide (CH3)2S. These VSCs are mainly produced by Gram-negative anaerobic oral bacteria (9). Most of these components are produced in the proteolytic degradation process of peptides. Other molecules involved in this bacterial degradation process are: cysteine, cystine, methionine, diamines (indole and skatole) or polyamines (cadverin and putrescin) (10).

Fig:no:1 Halitosis and it's microbiology

TONGUE COATING:

It is the most common cause of bad breath (11). The dorsum of the tongue, which is irregular and has a surface of 25 cm 2 is an ideal niche for oral bacteria (12). Since desqua- mating epithelial cells and food remnants are available, putrefaction occurs. Hence, the tongue surface seems to be an important reservoir in the recolonisation of tooth surfaces (13). Tongue coating is not easy to remove. Thus, instead of reducing the bacterial load daily scrapping of tongue will help to reduce the substrate for putrefaction (14).

MORNING BREATH:

Due to the reduced saliva production during night, anaerobic putrefaction will increase, causing the typical morning breath. This is a non-pathological form of halitosis. Proper oral hygiene measures will reduce this problem. Snel et al. (15), concluded that gender seems to play an unknown role in this phenomenon: women manifest higher VSC levels than men in the morning. The reason for this is yet to be confirmed.

ODONTOGENIC HALITOSIS:

Poor oral hygiene, dental plaque, dental caries, accumulation and putrefaction of food remnants and unclean acrylic dentures (worn at night or not regularly cleaned or with rough surfaces) contribute to bad breath (16). Gingivitis and periodontitis are the main causes of the problem (17). Necrotizing gingivitis or periodontitis cause extreme soiled odours. This disease is caused by opportunistic bacterial infections occurring in individuals with stress, malnutrition, insufficient oral hygiene, smoking or systemic diseases (18).

XEROSTOMIA:

Patients with a dry mouth often show an increased volume of plaque on teeth and tongue (19). The lack of salivary flow, leads to the disappearance of the antimicrobial activity of the saliva and the transition from Gram-positive bacteria to Gram-negative species (20). Hyposalivation can be caused by diabetes, Sjo gren syndrome, stress, depression, medication, mouth breathing and alcohol abuse. Research groups of Kleinberg and Koshimune described properly the correlation between the dry mouth and the increase of halitosis (22-23).

Moreover, other salivary factors that can influence the development of malodour are an increase of the salivary pH by the intake of amino acids, a change in the oxygen depletion (a reduction stimulates the metabolism of Gram-negative bacteria, responsible for higher VSC production) (24-25).

Xerostomia related to ageing.Almost 25% of the elderly suffer from a dry mouth (21).A recent study in elderly found the accumulation of bacterial plaque on the tongue, oral dryness, burning mouth, overnight denture wear, and lower educational levels to be significantly related to oral malodour (26).Although xerostomia is associated with aging, studies have demonstrated that salivary gland function is well preserved in the healthy geriatric population. Saliva seems to undergo chemical changes with aging. As the amount of ptyalin decreases and mucin increases, saliva becomes thick and viscous and presents problems for the elderly.

Drug induced xerostomia (drugs like anti- cholinergics, antihistamines and diuretics dry the mucosa). Other causes chronic mouth breathing, radiation therapy, dehydration and autoimmune diseases (as Sjo gren’s) can also diminish salivation, as can systemic illness such as diabetes mellitus, nephritis and thyroid dysfunction.

Xerostomia can lead to dysgeusia, glossodynia, sialadenitis, crack- ing and fissuring of the oral mucosa, and halitosis. Dry mouth symptom can be treated with hydration and sialagogues or with arti- ficial saliva substitutes. In patients with Sjo gren’s syndrome and in those who have undergone radiation therapy, pilocarpine has been used with good results (27).

OTHER ORAL CAUSES:

Stomatitis, intra-oral neoplasia, exposed tooth pulps (with necrotic content), extraction wounds (with blood cloth or purulent discharges), or crowding of teeth (favouring food entrap- ment) can also be involved (28). Moreover, peri-implantitis, peri-coronitis, recurrent oral ulcerations and herpetic gingivitis, are described as origin for bad breath (29).

ENT AND PULMONARY PATHOLOGY:

Maximally 10% of the oral malodour cases originate from the ears, nose and throat (ENT) region, from which 3% finds its origin at the tonsils (30). Larynx is never involved. Therefore, when a clinical investigation is performed, attention should first be paid to the tonsils: size, structure (invaginations, coating and hyperaemia) and presence of tonsilloliths (5). Pulmonary pathology. bronchiectasis, lung abscesses and other endobrochial chronic disorders, i.e. necrotizing pulmonic neoplasias may cause an unpleasant odour (31).

GASTRO-INTESTINAL PATHOLOGY:

The gastro-intestinal tract can only indirectly (haematogenic) influence bad breath. Most of the population and physicians still believes that oral malodor is due to gastro-intestinal problems.The latter is only correct in 0.5% of the cases (6).

METABOLIC DISORDERS:

Preti et al. discussed already in 1992 a number of non-oral causes for oral malodour. Several well-documented etiologies for non-oral malodour include renal failure, cirrhosis of the liver and diabetes mellitus. In addition, there appeared to be several other metabolic conditions involving enzymatic and transport anomalies (such as tri- methylaminuria) which lead to the systemic production of volatile malodours that manifest themselves as halitosis and/or altered chemoreception (32).

HEPATHOLOGY AND ENDOCRINOLOGY:

Even a reduced liver function can cause “fetor heptaticus”- a sweet; excremental odour (the breath of death) as a waste products are diminished through the lungs in reduced liver function condition. Fetor hepaticus is an expression of hepatic encephalopathy (33). Liver failure inhibits the detoxification in the whole body, causing unpleasant odours (34). Also some hereditary disorders can influence the breath: tyrosinemy is the most important example (cabbage odour). Endocrinology can also contribute to halitosis. Not only the hormonal cycle seems to influence the mouth odour, but also a lot of other intestinal diseases (35 and 36).

MEDICATION:

Next to medication resulting in a dry mouth (see above); recently the use of bisphosphonates can contribute to oral malodour. Bisphospho- nate-induced osteonecrosis is since 2003 a common problem (37). The product is used systemically in cases of malignant bone tumours and their metastases. Often this results in jawbone necrosis, a clear origin for a filthy odour. The necrotic sequesters should be removed and it is tried to cover up the necrotic area with a steeled flap(38).

DETECTION:

The gold standard is the organoleptic scoring, i.e., smelling the odour of the patient. For analysis of bad breath; actual method to be used is by gas chromatography or by means of portable volatile sulphur compound analysers.

ORGANOLEPTIC SCORING:

In expired air, more than 150 different components have been detected. The perception of these molecules is dependent of the olfac- tory response, the threshold concentration, the strength of the odour and the volatility of the molecules. When organoleptical scoring is performed, a well-trained clinician determines if the odour samples smells bad or not, giving a score to the intensity. Theses scores go from 0 upto 5.(Table:1)

From every patient, different samples are analysed:

· mouth odour (smelled at 10 cm form the oral cavity: while the patient normally breaths and while the patient counts loudly to 10);

· saliva odour (measured by the wrist-lick test: the patient licks at the wrist, and after 10 s of drying, a score is given to this sample);

· tongue coating (a score is given to debris, scraped from the dorsum of the tongue with a periodontal probe);

Table:1 Organoleptical Scoring Scale

· interdental ‘floss’ (after flossing with dental tape, the odour of the floss is scored);

· nasal odour (while the patient is breathing through the nose (mouth closed), a score is given to the exhaled air);

· prosthesis odour (if the patient wears a partial or full removable denture, scoring of the odour of this prosthetic is noted).

To gather accurate test results the patients should avoid spicy foods, garlic and onions the day before the examination.

At least 12 h before the consultation, teeth should not be cleaned or rinsed, perfumes should be avoided and at least 6 h before the examination, the intake of food or liquids should be avoided. Smoking should be stopped at least 24 h before any examination (39).

The advantages of organoleptical scoring are: inexpensive, no equipment needed and a wide range of odours is detectable. As dis- advantages, the extreme subjectivity of the test, the lack of quantification, the saturation of the nose and the reproducibility can be mentioned (40). Still, organoleptic scoring is considered as the gold standard in the detection of oral bad breath.

PORTABLE GAS ANALYSIS:

Electronic devices like Halimeter and oral chroma are used to detect volatile sulphur components in the expired air. The Oral Chroma is a portable gas chromatograph offering lower cost, higher performance and more user-friendly operations than conventional gas chromato- graphs by limiting the target gases to three types: H2S, CH3SH and (CH3)2S and even the interpretation of the results can be shown to the patients. The Halimeter can only give an idea of the total amount of VSCs, present in a sample. In the Halimeter, the total amount ppb (parts per billion) of VSCs in the sample is marked. In normal situations this value is less than 100 ppb. When 300–400 ppb are detected in the mouth air, a persistent oral odour can be concluded(41and42).These portable machines have a lot of advantages: easy to handle, fast results, portable and reproducible. Furthermore, they are rather inexpensive and can be controlled by untrained staff. As disadvantage, the limited diversity in the explored gasses should be stated. Recently, it was shown that the OralChroma may produce a more comprehensive assessment of VSC production by oral microflora than the Halimeter(43).It would desirable to select one machine as gold standard to make different studies comparable in the future.

Fig no:2 Halimeter.

GAS CHROMATOGRAPHY:

In halitosis research, the gas chromatography (GC) analysis can be performed on breath, saliva and tongue debris. Almost all different air components can be detected. In expired air, almost 500 different sub- stances can be demonstrated (44). GC in malodour research is still in an experimental stage, although used since the late 1960s (45).VSCs can be well detected, but the challenge will be to analyze the other contributing components of oral malodour. Even different odours associated with systemic disease can be investigated using gas chromatography.GC has several advantages: an analysis of almost all components with high sensitivity and specificity. The method is non-invasive, but expensive and a well-trained staff is needed. The progression of the method takes much more time and the machine cannot be used in daily practice (46).

Recently, trailblazing research was performed by van den Velde et al.(47and34),with gas chromatography–mass spectrometry as a tool for differential diagnosis of halitosis, with the possibility to detect extra- oral causes, which often remain undetected unless characterized by a specific smell.

THERAPEUTIC APPROACH TO MANAGE ORAL HALITOSIS:

Successful treatment of halitosis depends on a correct diagnosis and the implementation of a cause-related therapy (48). After a positive diagnosis for oral halitosis has been made, the treatment plan is implemented, which comprises elimination of the causative agent and improvement of the oral health status (49).Although the multiple possible etiologies include oral and non-oral causes, the majority of breath malodor cases originate from the oral cavity. Briefly, the treatment of oral malodor can therefore be focused on the reduction of the intraoral bacterial load and/or the conversion of VSC to nonvolatile substrates.

Miyazaki et al(50). (1999) established the recommended examination for halitosis and a classification of halitosis with corresponding treatment needs. Accordingly, different treatment needs (TN) have been described for the various diagnostic categories. The responsibility for the treatment of physiologic halitosis (TN-1), oral pathologic halitosis (TN-1 and TN-2), and pseudo-halitosis (TN-1 and TN-4) resides on dental practitioners. However, extra-oral pathologic halitosis (TN-3) and halitophobia (TN- 5) should be managed by a physician or medical specialist and a psychiatrist or psychological specialist. Table 1 describes the 5 different categories of treatment needs according to diagnosis (Miyazaki et al.22, 1999).

The management of halitosis starts by taking a detailed history of the condition, duration, severity, and impact on the patient’s everyday life. Examination involves clinical, radiographic, and special tests. The contributing medical conditions, once identified, are referred for treatment accordingly. Clinical examination checks the patient’s oral hygiene, caries, and periodontal status; plaque retention factors are also recorded. Radiographic examination should look for evidence of dental caries, alveolar bone defects, and defective restorations.21 Special tests are performed to detect the foul-smelling VSCs along with the associated bacteria. The results collected can be used to confirm the diagnosis and to monitor the treatment progress. There are many diagnostic techniques among which are organoleptic measurement, gas chromatography, and halimeter examination (51-54).

Since malodor originating from the mouth is due to the metabolic degradation of available proteinaceous substrates to malodorous gases by certain oral microorganisms, oral malodor can be ameliorated through: (1) Reduction of bacterial load, (2) reduction of nutrient availability, (3) conversion of VSC to nonvolatiles and (4) masking the malodor(1,48,55)

TABLE:2 Treatment needs (TN) for breath malodor divided in 5 categories

Reference: José Roberto Cortelli, Mônica Dourado Silva Barbosa, Miriam Ardigó Westphal- Halitosis: a review of associated factors and therapeutic approach.

CONCLUSION:

Halitosis is a common condition, affecting around 25% of the general population. The major cause of halitosis is found to be intra-oral causes only limited number of cases are found to be extra-oral or systemic causes. Nevertheless, proper investigation and management of these extra oral causes is important for the total under- standing of this phenomenon. Halitosis from an extra-oral origin can be the sign of an underlying systemic disease. Therefore, it is substantiated to organize halitosis consultations in a multidisciplinary setting, assembling periodontologists, ENT specialists, specialists in internal medicine and psychologists or even psychiatrists.

Although oral malodour is mostly associated with poor oral hygiene and the presence of gingivitis or even periodontitis, evidence suggests that anaerobic microorganisms present in the tongue coating, are the overwhelming cause of this condition. A limited number of successful treatment regimens have been described, but more research on the long-term outcomes of these therapies will be required. Also new and more long lasting in-office treatments should be developed and tested.

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Received on 01.06.2017 Modified on 31.07.2016

Research J. Pharm. and Tech 2017; 10(11): 4024-4029.

DOI: 10.5958/0974-360X.2017.00729.6