Examination and gum screening
A dentist checks every tooth and restoration, measures the gum around each one and looks at the tongue and soft tissues. X-rays are taken only where something needs a closer look.
About this treatmentDental condition · Wimpole Street, Marylebone
Bad breath: finding the dental cause of halitosis
Nine times out of ten, a breath problem begins between the teeth, under the gum margin or on the back of the tongue rather than in the stomach. That is good news, because it means a dentist and hygienist can usually find the source and deal with it. Odour is produced when bacteria break down protein in trapped food, plaque and dead cells, releasing sulphur gases. Anything that lets those bacteria settle undisturbed, such as gum pockets, a leaking filling, a cavity or a coated tongue, gives them a head start. Our Wimpole Street team will look for those hiding places, ask about saliva, medicines and habits, and give you a clear plan rather than another mouthwash.
Recognising it
How it usually feels
Odour that returns within an hour or two of brushing
Suggests bacteria are surviving somewhere your brush is not reaching.
A white, grey or yellow film on the back of the tongue
The rough surface of the tongue is one of the richest sources of sulphur compounds.
Gums that look puffy or bleed on flossing
Inflamed gum tissue and the pockets around it are classic culprits.
A stale or bitter taste, worst first thing in the morning
Saliva slows overnight, so bacterial activity climbs while you sleep.
Food packing in one particular spot
Points towards a gap around a filling, crown or a cavity that is trapping debris.
Friends or family noticing before you do
People habituate to their own breath, so honest feedback is genuinely useful.
Behind the symptoms
What's going on
- 01
Plaque left along the gum margin and between teeth
Most of us brush the flat surfaces well and miss the slots between teeth and the line where gum meets tooth. Plaque left in those zones matures within a day or two and shifts towards the anaerobic bacteria that produce volatile sulphur compounds, which are what you and others actually smell.
- 02
Gum inflammation and periodontal pockets
When the gum becomes inflamed it pulls slightly away from the tooth, creating a warm, oxygen-poor pocket. Bacteria thrive there and the tissue itself may bleed and weep, adding protein for them to break down. Deeper pockets from periodontitis are harder still to keep clean at home.
- 03
A coated tongue
The back third of the tongue has a rough, papillated surface that collects dead cells, mucus from the nose and throat, and bacteria. Very few people clean it, yet it can account for a large share of the odour even in mouths with healthy gums.
- 04
Cavities, cracked teeth and ageing restorations
A hole in a tooth, a crack, or a worn filling or crown margin all create ledges and gaps that hold decomposing food. An infected tooth or abscess draining into the mouth produces a particularly distinctive smell and taste.
- 05
Reduced saliva
Saliva rinses, buffers and contains antibacterial proteins. Mouth breathing, many common medicines, dehydration and some medical conditions lower flow, so bacteria are simply washed away less often. Morning breath is the everyday version of this.
- 06
Things beyond the mouth
Sinus and tonsil problems, smoking, certain foods and, less commonly, digestive or metabolic conditions can all contribute. We flag these when the mouth looks healthy and the story does not fit, and suggest you speak to your GP.
Before your appointment
What you can do today
- Clean between every tooth once a day with floss or interdental brushes sized to fit the gaps, and brush for a full two minutes twice a day with a fluoride toothpaste.
- Gently clean the back of the tongue with a tongue scraper or the back of a soft brush, working from as far back as is comfortable towards the tip.
- Drink water regularly through the day and chew sugar-free gum after meals to keep saliva moving.
- Do not rely on mouthwash to mask the problem; if you use one, choose an alcohol-free product and treat it as a supplement rather than a fix.
- Keep a note of when the odour is worst and what you have eaten, taken or done, which helps us narrow the cause quickly.
These are holding measures, not a substitute for an examination. Use any pain relief exactly as directed on the pack and check with a pharmacist if you take other medicines.
In the chair
How we treat it at Wimpole Street
Hygiene visit
Removal of plaque and hardened tartar above and just below the gum margin, followed by polishing and a frank, practical review of your cleaning technique and tools.
About this treatmentGum treatment for deeper pockets
Where pockets are found, cleaning is extended beneath the gum under local anaesthetic, usually over a couple of visits, then reviewed to check the tissue has tightened.
About this treatmentRepairing decay or failing fillings
Any cavity or leaking restoration that is trapping debris is cleaned out and rebuilt with tooth-coloured composite, removing the reservoir of bacteria.
About this treatmentFees
Costs to expect
A routine examination at Wimpole Street is expected to be £95, with a hygiene appointment from £89. For most people with halitosis these two visits are the whole plan, followed by improved home care and a review a few months later.
If gum pockets need deeper cleaning, gum treatment is quoted per session after the screening. Should a cavity or worn filling be part of the story, white fillings start from £185 per tooth. Every recommendation is written down with its fee before anything is booked.
Figures are indicative prices for Wimpole Street and are confirmed in a written plan once a dentist has examined you. Fees match our South Kensington and St Paul's clinics.
Don't wait if
When to see a dentist
- Breath odour has persisted for more than three or four weeks despite thorough daily cleaning.
- Your gums bleed when you brush or floss, or look red and swollen.
- You can taste something unpleasant coming from one area of the mouth.
- A tooth has become sensitive, tender or painful alongside the odour.
- Your mouth feels dry much of the time or you have recently started a new medicine.
- You have not had a dental examination in the last twelve months.
FAQ
Common questions
Genuine stomach-related halitosis is unusual. A quick self-check is to floss between the back teeth and smell the floss, or to scrape the back of the tongue with a clean spoon and smell that after a few seconds. If either is strong, the mouth is almost certainly the source and a dental visit is the right first step.
Often it makes a noticeable difference within days, because the hardened deposits that shelter bacteria are removed. Whether it lasts depends on home care afterwards and on whether deeper gum pockets, a cavity or a dry mouth are also involved. That is why we screen before we clean.
For many people, yes. The tongue coating is a major source of sulphur gases and neither brushing the teeth nor rinsing removes it. A daily gentle scrape, without pressing hard enough to make you gag or bleed, is one of the simplest changes with a real effect.
If you want one, choose an alcohol-free formulation, as alcohol dries the mouth and can worsen odour later in the day. Products containing zinc or cetylpyridinium chloride have some evidence for neutralising sulphur compounds. None of them treats the cause, so think of mouthwash as a finishing touch.
In the mouth it can indicate gum disease or an infected tooth, both of which need treatment but are very manageable. Rarely, persistent odour with a healthy mouth reflects a sinus, throat, respiratory or metabolic issue, and we would suggest you see your GP if our examination finds nothing to explain it.
It becomes more likely, mainly because saliva flow tends to fall, more medicines are taken, and gum pockets and older restorations accumulate over the years. None of that is inevitable, and the same measures work at any age.
Marylebone, W1
Wimpole Street opens 1 October 2026
Leave your details and we will be in touch when the Marylebone diary opens. If the problem cannot wait, the same clinicians are already seeing patients in South Kensington and at St Paul's.
Related conditions
Opening 1 October 2026
Wimpole Street is not yet seeing patients. Until then, please book or call our South Kensington clinic on 020 7183 2362 or our St Paul's clinic on 020 7183 3709. Questions about the new clinic: wimpolestreet@md.co.uk.
Until we open
Need an appointment before 1 October 2026?
The same clinical team already works from two other Medical & Dental clinics. Book at either one now and, if you prefer, move your ongoing care to Wimpole Street once the doors open.
South Kensington
- 20 Old Brompton Road, London SW7 3DL
- Open seven days a week
- 020 7183 2362
St Paul's, City of London
- 5 Ave Maria Lane, London EC4M 7AQ
- Open Monday to Friday
- 020 7183 3709
