Bad breath, or halitosis, is a frequent reason for consultation, often experienced as a lasting social embarrassment and sometimes discovered by chance during a scaling appointment. Epidemiological studies estimate that around one person in four is affected by persistent halitosis at some point in their life, with a prevalence that rises with age. In the great majority of cases (in the order of 85 to 90%), the origin is strictly oral, so the problem falls in the first instance to the dentist and the dental hygienist. The remaining cases (10 to 15%) stem from ENT, digestive, metabolic or, more rarely, systemic causes, and require coordination with other specialists.
The aim of this article is to offer a factual overview of halitosis, drawing a clear distinction between transient and chronic forms, detailing the main pathophysiological mechanisms, setting out the diagnostic process carried out in the dental practice, and presenting the treatment options currently available. No “miracle” cure is promised here: managing halitosis rests on a rigorous identification of the cause, followed by a tailored protocol, which is almost always effective when the origin is oral.
1. Transient halitosis and chronic halitosis: two distinct realities
Halitosis is defined as a measurable alteration of the odour of exhaled air, perceived as unpleasant by those nearby. It divides into two broad clinical categories.
Transient halitosis is physiological. It appears on waking (the overnight reduction in salivary flow), after eating foods rich in sulphur compounds (garlic, onion, certain cheeses), coffee, alcohol or tobacco, or during prolonged fasting. It clears on its own with brushing, hydration and chewing, and does not call for medical management.
Chronic halitosis is a persistent bad odour, present several times a week for more than three months, regardless of diet. It is this form that warrants a structured assessment. Alongside these two entities, there is also pseudo-halitosis (the patient complains of bad breath that examination does not confirm) and halitophobia (a persistent fear of having bad breath despite a reassuring objective examination and the resolution of any genuinely treated halitosis). These situations call for a different, more reassuring approach, sometimes combined with psychological support, and must not lead to unnecessary dental treatment.
2. Oral origin: 90% of cases
The vast majority of chronic halitosis originates in the oral cavity, where anaerobic bacteria break down salivary proteins, shed epithelial cells and food debris into volatile sulphur compounds (VSCs). The three main VSCs identified are hydrogen sulphide, methyl mercaptan and dimethyl sulphide. These molecules, detectable with dedicated instruments, are responsible for the characteristic odour.
The back of the tongue: the first area to examine
The posterior third of the tongue is anatomically the area most often involved. Its villous surface, irregular and poorly self-cleaning, harbours a dense bacterial biofilm that is particularly rich in anaerobic VSC-producing germs. It is estimated that close to 60% of the mouth’s bacteria reside on the tongue surface, and that the tongue alone accounts for around 40% of oral halitosis. A whitish or yellowish tongue coating visible on examination is a very common clinical sign.
Periodontal disease
Gingivitis and, above all, periodontitis (chronic infection of the supporting tissues of the tooth) are a major cause of halitosis. Periodontal pockets provide an ideal anaerobic environment for VSC-producing bacteria, notably Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola. Persistent halitosis associated with gum bleeding, tooth mobility or gum recession should first and foremost raise the suspicion of periodontitis. According to the Swiss Society of Periodontology, close to 40% of adults are thought to be affected by periodontal disease, and around half of them report associated halitosis.
Deep cavities and infectious foci
A cavitated lesion, a residual root, an infected non-vital tooth or a periapical focus (granuloma, cyst) constitute a bacterial reservoir capable of generating persistent odours. Radiographic diagnosis usually allows the lesion to be identified quickly.
Defective prostheses, crowns and restorations
A poorly maintained removable denture, a crown with a defective margin, or an overhanging filling that creates a plaque trap, all sustain local inflammation and encourage bacterial proliferation. Daily cleaning of removable dentures (brushing, antiseptic soak) and regular checking of the fit of fixed restorations are essential.
Reduced salivary flow and dry mouth
Saliva plays a major role in self-cleaning and antimicrobial buffering. Any reduction in salivary flow increases bacterial proliferation and VSC production. The causes of reduced salivary flow are numerous: age, chronic mouth breathing, dehydration, medication (antidepressants, antihypertensives, antihistamines, certain diuretics), radiotherapy to the head and neck, and Sjogren’s syndrome. Morning halitosis, more marked in everyone, illustrates this effect: the physiological drop in salivary flow during sleep is enough to let the oral flora proliferate.
3. Extra-oral origins: when to consider them
When the dental and periodontal examination is strictly normal, hygiene is rigorous and halitosis persists, an extra-oral origin should be considered. It accounts for 10 to 15% of chronic halitosis. Several broad categories should be explored.
ENT origin
Chronic sinusitis, chronic rhinitis with postnasal drip, cryptic tonsils (with the formation of tonsil stones, those small whitish, malodorous deposits lodged in the tonsillar crypts), chronic pharyngitis and certain tumours of the upper aerodigestive tract can all generate halitosis. An odour perceived both through the mouth and through the nose points towards an ENT or deeper cause. A consultation with an ENT doctor is indicated in the case of a history of sinusitis, postnasal drip, chronic throat discomfort or visible tonsil stones.
Digestive origin
Contrary to a very widespread belief, the stomach is only exceptionally responsible for bad breath. The lower oesophageal sphincter, when competent, effectively isolates the oral cavity from the gastric contents. The rare confirmed digestive causes involve severe gastro-oesophageal reflux, certain large hiatal hernias, Zenker’s diverticulum (a pouch of the cervical oesophagus where food stagnates) and, more rarely, Helicobacter pylori infection. A gastroenterology opinion is useful where there are associated digestive symptoms: heartburn, regurgitation, difficulty swallowing or epigastric pain.
Metabolic and systemic origin
Certain general illnesses alter the composition of exhaled air. Diabetic ketoacidosis gives a characteristic fruity odour (acetone). Liver failure can produce a foetor hepaticus, a sweetish odour linked to the build-up of mercaptans. Advanced chronic kidney failure is accompanied by an ammonia-like odour (foetor uraemicus) from the build-up of urea. Rare metabolic disorders (trimethylaminuria, or “fish odour syndrome”) can also present with a particular form of halitosis. These causes remain exceptional, but should be considered in the face of atypical halitosis, especially if it is accompanied by general signs.
4. Why self-assessment is unreliable
Many patients try to assess their own breath by breathing into a cupped hand, licking the inside of the wrist, or scraping the back of the tongue. These methods are poorly reproducible and weakly correlated with the objective perception of a third party, for two main reasons. First, the human sense of smell adapts quickly to its own odours (olfactory adaptation): we quickly stop perceiving an odour to which we are continually exposed. Second, the soft palate and the posterior part of the oral cavity, where VSCs are concentrated, are not reached by air expelled towards the hand.
Conversely, some people convinced that they have bad breath show no measurable halitosis on examination. This mismatch between subjective perception and clinical reality justifies a professional diagnosis rather than self-assessment, especially before considering repeated treatments or costly products. The role of the dental practice is precisely to confirm the symptom objectively before treating it.
5. The diagnostic process in the practice
Diagnosing chronic halitosis in the dental practice follows a structured process, combining history-taking, clinical examination, objective measurements and, where necessary, referral to a colleague.
History-taking
This covers how long the complaint has been present, the circumstances in which it appears (on waking, constant, after meals), hygiene habits, smoking, diet, current treatments, and ENT and digestive history. It also looks at the social and psychological impact: avoiding close contact, changing the way one speaks, relying on mints. A complaint reported by those around the patient is an important argument in favour of genuine halitosis, as opposed to halitophobia.
Clinical examination
The examination systematically explores the teeth (cavities, restorations), the gums (bleeding on probing, depth of periodontal pockets), the tongue (coating, fissures, candidiasis), salivation (volume, viscosity), the mucosa and the tonsils. The presence of generalised periodontal bleeding or a thick posterior tongue coating strongly points towards an oral cause.
Organoleptic assessment
This is the reference method. At about ten centimetres, the practitioner directly assesses the odour of the air exhaled through the mouth and then through the nose, after a period without speaking, eating, smoking, coffee, scented products or chewing gum in the preceding hours. A rating on what is known as the Rosenberg scale, from 0 (no odour) to 5 (very strong odour), allows the intensity to be quantified. Comparing the oral and nasal odour guides the topographical diagnosis: an odour from the mouth only indicates an oral origin, an identical odour through mouth and nose points towards a systemic cause or the deep airways, and an odour through the nose only suggests an ENT cause.
Instrumental measurements
Several instruments allow VSCs in exhaled air to be measured objectively. The halimeter is a portable electrochemical sensor that measures total sulphides in parts per billion (ppb). Gas chromatography (OralChroma and equivalent systems) separates and individually quantifies the three main VSCs, which provides an additional pointer: a raised methyl mercaptan suggests periodontitis, a predominant hydrogen sulphide points towards a tongue cause, and a dominant dimethyl sulphide suggests an extra-oral origin. These measurements are painless, quick, and particularly useful for confirming improvement under treatment.
ENT and digestive work-up
When the oral examination is normal and VSCs are abnormally high, or where there are signs pointing to another origin, the assessment is completed by an ENT consultation and, more rarely, a gastroenterology opinion. Coordination between practitioners is essential so as not to multiply unnecessary treatments.
6. Management: treat the cause, not the odour
The central principle is simple: treat the cause and do not mask the odour. Scented mouthwashes, chewing gum and mint sprays can be of occasional help, but they provide only a few minutes’ benefit and treat nothing. The treatment protocol is organised according to the identified origin.
Targeted tongue hygiene
When a posterior tongue coating is responsible, brushing the tongue with a soft toothbrush or, better still, a dedicated tongue scraper, becomes a daily step. The movement is made from back to front, without forcing, after brushing the teeth. This simple measure can significantly reduce measured VSCs, provided it is carried out daily and with the correct technique. The dental hygienist is the go-to person to teach this technique, check that it is being performed correctly and adapt the instrumentation.
Scaling and professional cleaning
Removing the bacterial biofilm and supragingival calculus is an essential step. The GBT, Guided Biofilm Therapy protocol begins by revealing the biofilm with a food-grade dye, which lets the patient see their areas of accumulation, then uses an air polisher with a fine erythritol powder to lift the biofilm without damaging the tissues, and finishes with piezoelectric ultrasound for any remaining calculus. The approach is less traumatic than conventional scaling, more effective in the shallow sub-gingival area, and particularly well tolerated.
Periodontal treatment
Where periodontitis is present, treatment begins with a non-surgical phase known as the aetiological phase: root planing (also called periodontal debridement or periodontal curettage) under local anaesthetic, which involves cleaning the root surfaces beneath the gum and removing the sub-gingival biofilm. Periodontal re-evaluation, two to three months after this phase, allows the reduction in pockets and the resolution of bleeding to be measured. Periodontal surgery may be necessary in the most advanced cases. The fall in VSCs generally parallels periodontal healing.
Treating infectious foci
Any cavitated lesion, residual root or endodontic lesion is treated according to the usual rules: restoration, root canal treatment, root canal retreatment or extraction. Removing the bacterial reservoir brings about a lasting fall in VSCs.
Redoing defective prostheses and restorations
An open crown, an overhanging filling or a bridge at the limit of its fit are redone. Removable dentures are the subject of maintenance education: daily mechanical cleaning, a weekly soak in a suitable solution, and removal at night.
Tackling reduced salivary flow
When dry mouth is responsible, regular hydration is encouraged, along with chewing (sugar-free xylitol chewing gum to stimulate salivary flow), avoidance of alcohol-based mouthwashes (which worsen dryness), and the use of saliva substitutes in cases of severe reduction in salivary flow. Reviewing medications that dry the mouth with the treating doctor can be helpful.
Mouthwashes: a complement, not a treatment
Mouthwashes containing chlorhexidine, cetylpyridinium chloride, stannous fluoride or hydrogen peroxide have shown short-term efficacy in reducing VSCs. They may be offered as a complement to aetiological treatment, for a limited period. Chlorhexidine is not indicated long term because of its side effects (tooth staining, taste alterations). Over-the-counter mouthwashes, alcohol-based and scented, should be regarded as cosmetic, not therapeutic.
Smoking cessation
Tobacco worsens halitosis through several mechanisms: the inherent odour of smoke compounds, the worsening of periodontitis, reduced salivary flow, and changes to the oral flora. Smoking cessation is systematically encouraged in the smoker with halitosis, supported where necessary by appropriate medical follow-up.
7. When to seek a consultation
Halitosis that persists for several weeks, that is not improved by correct oral hygiene (twice-daily brushing, floss or interdental brushes, tongue brushing), that is accompanied by gum bleeding, a persistent unpleasant taste or a sensation of dry mouth, or that affects social life, warrants a consultation. An annual check-up with the dental hygienist and the dentist is also recommended for the general population, regardless of any complaint of halitosis, and is the best form of prevention.
In certain situations, the consultation should be sought more quickly: halitosis associated with toothache or swelling (suspected abscess), significant spontaneous gum bleeding, tooth mobility, associated unexplained weight loss, or a palpable neck mass. These signals warrant an opinion within a few days, not a prolonged wait.
8. At Chantepoulet Dental Clinic
Chantepoulet Dental Clinic offers a multidisciplinary approach to halitosis, from the initial assessment through to aetiological treatment. The team of dental hygienists (Aurelie Phan, Emilie Gross, Aurelie Lagin) carries out the clinical assessment of hygiene, personalised teaching of brushing and interdental cleaning, instruction in tongue brushing, as well as scaling using the GBT protocol. The dentists manage cavities, defective restorations and the re-education of denture care. The oral surgeon Dr Alice Jurt handles the periodontology and surgery aspects when the situation requires it, in particular in the case of confirmed periodontitis.
The technical facilities include the GBT protocol for scaling and professional cleaning, as well as an operating microscope that provides valuable magnification for endodontic care and for detecting fissures or defective prosthetic margins that may sustain halitosis. Optical impressions also make it possible to plan precisely the replacement of ill-fitting crowns or prostheses.
The clinic is located at Rue de Chantepoulet 21, 1201 Geneva, around 300 metres from Cornavin station. The opening hours are as follows: Monday to Friday from 8am to 7pm, and Saturday from 8am to 5pm. Appointments can be booked by telephone on +41 22 547 44 44, online or via the OneDoc platform. For a complete and personalised assessment of persistent halitosis, booking an appointment with a dental hygienist in Geneva is a concrete and structuring first step in the diagnostic process.
