Gum assessment
Pocket depths and bleeding are charted across the mouth to find where the odour is coming from. We also inspect the tongue, check for dry mouth and look at fillings and crowns that could be trapping plaque.
About this treatmentDental condition · Wimpole Street, Marylebone
Persistent bad breath from the gums: why pockets smell and what actually clears it
Breath that is unpleasant first thing in the morning is universal and disappears with breakfast and a brush. Breath that stays unpleasant through the day, that returns within an hour of cleaning and that mints and mouthwash only mask has a source, and in most adults that source is the gums. Bacteria living in the crevice between gum and tooth, and especially in the deepened pockets of gum disease, break down proteins from food, blood and dead cells into volatile sulphur compounds. These are the same chemicals that give rotten eggs and cabbage their smell, and they are produced continuously wherever bacteria sit undisturbed in a warm, oxygen-poor space. A toothbrush cannot reach into a pocket, so the odour persists however carefully you clean the surfaces you can see. The good news is that gum-related bad breath is one of the more treatable causes: remove the bacterial deposits, shrink the pockets and the sulphur production falls sharply. At Wimpole Street our hygienists and dentists find the sites responsible and treat them rather than prescribing another rinse.
Recognising it
How it usually feels
Odour that returns soon after brushing
The source is below the gum where the brush cannot reach.
A sulphurous or metallic taste, worst on waking
Sulphur compounds and blood from inflamed pockets accumulating overnight.
Floss that smells after use
A direct sample of the bacteria between the teeth and under the gum.
Gums that bleed when cleaning
Blood is a rich protein source for odour-producing bacteria.
A coated tongue
The tongue harbours the same bacteria and amplifies the smell.
Other people mentioning it, or stepping back
You cannot reliably smell your own breath; feedback from others is often the first clue.
Behind the symptoms
What's going on
- 01
Periodontal pockets
When the gum detaches from the root, a pocket several millimetres deep forms. It is warm, wet, sheltered and starved of oxygen, exactly the environment in which sulphur-producing bacteria thrive. The deeper and more numerous the pockets, the stronger the odour.
- 02
Gingivitis and bleeding
Even before pockets form, inflamed gum margins bleed and leak fluid rich in protein. Bacteria break this down into foul-smelling compounds. Treating gingivitis frequently resolves bad breath at the same time.
- 03
Tartar and plaque traps
Hardened calculus below the gum is porous and coated with bacteria. Overhanging fillings, crown margins and tightly packed teeth hold plaque where ordinary cleaning misses it.
- 04
Tongue coating
The back of the tongue has a rough surface that collects bacteria and debris. It contributes to bad breath in most people and interacts with gum disease, since the same organisms colonise both.
- 05
Dry mouth
Saliva rinses the mouth and neutralises odour. Medicines, mouth breathing, dehydration and some medical conditions reduce flow, concentrating the bacterial products and worsening breath from any gum source.
- 06
Non-gum sources
Tonsil stones, sinus infections, reflux and certain metabolic conditions can cause persistent bad breath. If the gums are healthy and the tongue is clean, we will say so and suggest your GP looks elsewhere.
Before your appointment
What you can do today
- Clean between all the teeth once a day with interdental brushes or floss; this reaches the spaces where most odour originates.
- Scrape or brush the back of the tongue each morning, gently, working from as far back as you can manage.
- Brush along the gum line for two minutes twice a day; bleeding is a reason to continue, not to stop.
- Drink water through the day and chew sugar-free gum after meals to keep saliva moving.
- Use a mouthwash containing chlorhexidine, cetylpyridinium or zinc for short periods only; it masks rather than treats and long-term chlorhexidine stains the teeth.
- Reduce smoking and alcohol, both of which dry the mouth and feed the problem.
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
Professional cleaning
For gingivitis and shallow pockets, a thorough scale and polish or Airflow session removes the deposits, and the hygienist tailors your home cleaning to the spaces where you are missing.
About this treatmentPeriodontal treatment
Deeper pockets are cleaned under local anaesthetic over several visits, removing the bacterial film and calculus from the root surfaces. As pockets shrink, the sulphur-producing population collapses.
About this treatmentCorrecting plaque traps
Ledges on fillings are smoothed, defective crowns re-margined and food-packing contacts reshaped so that the areas can be kept clean at home.
About this treatmentDry mouth management
Where saliva is low we identify contributing medicines with your GP and recommend substitutes and stimulants, because a dry mouth undermines every other measure.
About this treatmentMaintenance
Regular hygiene visits keep pockets shallow and deposits from re-forming, which is what keeps the breath fresh over the long term.
About this treatmentFees
Costs to expect
An examination at Wimpole Street to identify the cause of bad breath, including gum charting, is expected to be £95. A hygiene visit is from £89, or £142 with Airflow, and for gingivitis this together with improved home care usually resolves the problem.
Where periodontitis is found, a treatment course is indicative from £850 depending on the number of pockets, followed by maintenance visits from £89. Replacing a filling with an overhang that traps plaque is from £185. Fees are confirmed in writing after the assessment, and if the gums prove not to be the cause we will say so rather than treat them anyway.
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
- Bad breath that persists despite careful brushing and flossing.
- Gums that bleed, look red or have pulled away from the teeth.
- A constant bad taste in the mouth.
- A partner or colleague has commented on your breath more than once.
- You have a dry mouth alongside the odour.
- A swollen or painful gum with pus, which needs prompt attention.
FAQ
Common questions
Because it neutralises the sulphur compounds already present and briefly reduces the bacteria on the surfaces it touches, but it cannot penetrate a pocket or dislodge the film of bacteria on root surfaces. Within an hour production resumes. Treating the pockets removes the factory rather than clearing the fumes.
Floss between your back teeth and smell the floss; a foul odour points to the gum crevices. Bleeding on brushing, a bad taste on waking and a history of gum problems all support it. The definitive answer comes from having the pockets measured, which takes a few minutes.
If the gums are the source, treatment reduces the odour markedly in the large majority of cases, usually within a few weeks of the pockets healing. If breath remains a problem with healthy gums and a clean tongue, another source is likely and we will help you pursue it with your GP.
It can be. Persistent odour is one of the few symptoms of periodontitis that people notice, since the disease is otherwise painless. It does not necessarily mean the disease is advanced, but it is a reason to have the gums assessed rather than to rely on mints.
For most people, yes. The coating on the back of the tongue is a major reservoir of odour-producing bacteria, and gentle daily scraping reduces sulphur levels measurably. It works alongside gum treatment rather than instead of it.
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
