A bad smell or taste from an implant: what causes it, and when should you see a dentist?

Bad breath is produced by bacteria: as they break down the protein in food debris and shed cells, sulphur gases are released. These bacteria like corners where there is little oxygen and where the brush and saliva do not reach. In a mouth with implants, the addresses of these corners are known: the underside of the bridge facing the gum, the neck area where the implant emerges from the gum, the space above the screw of the top part and the gap where the implant and the top part join. The way to solve the smell is to find which of these addresses is responsible.

The first and most common source is under the bridge. A fixed bridge or full-arch prosthesis sits close to the gum; food and plaque build up in the gap underneath, and a flat toothbrush does not reach there. In a study in Sweden of 23 patients referred to a hospital's periodontology department because of inflammation around an implant, about two thirds (65%) of the implants with no access for oral hygiene had inflammation; among implants with access, the figure was about 18%. Three quarters of the implants were in a state that could not be cleaned. The authors emphasise the importance of a prosthesis design that allows cleaning around the implants. This study is small and made up of referred patients; it does not prove the cause, but it shows the link between inflammation around an implant and a surface that cannot be cleaned.

The second source is the screw hole. In bridges held in place with screws, there is a channel above each implant to give access to the screw. This channel is usually closed first with a filling material and, at the very top, with a tooth-coloured filling. If the filling at the top wears or falls out, food and saliva fill the channel and a stubborn smell coming from a single point can start. In a laboratory study, cotton placed in the screw channel was shown to accumulate more microbial biofilm than gutta-percha and Teflon tape (PTFE); this is a laboratory finding and does not directly measure smell in the mouth. When the screw loosens, bacteria can also build up in the connection gap; we have explained screw loosening on a separate page.

The third source is inflammation of the gum around the implant. The consensus report of the 2017 World Workshop defines this in two stages. The first stage is peri-implant mucositis: its main finding is bleeding on gentle probing; there may also be redness, swelling or pus, and the consensus report writes that there is strong evidence that plaque is the cause of this picture. The second stage is peri-implantitis: a disease associated with plaque that involves inflammation in the tissue around the implant followed by progressive bone loss. Its findings include bleeding or pus on probing, deepening pockets, recession of the gum margin and bone loss on the X-ray. Pus and dead tissue give a distinct smell and taste.

These pictures are not rare. In a systematic review combining eleven studies, the weighted mean prevalence of peri-implant mucositis was calculated as 43% and that of peri-implantitis as 22%; in individual studies the rates ranged from 19 to 65% and from 1 to 47% respectively. The authors state that differences in definition are the main reason for this wide range and that the prevalence of peri-implantitis increases the longer the implant has been in the mouth. The European Federation of Periodontology also writes that peri-implantitis develops in about 22% of implants in people who have had gum disease.

The insidious side of the inflammation is that it can progress without pain. There is no nerve inside an implant; no ache warns you as it would with a natural tooth. That is why a bad smell or taste, sometimes together with bleeding when you brush, may be the first sign that is noticed. The European Federation of Periodontology recommends that when you notice one of the signs of inflammation, you make an appointment with your dentist or your periodontist as soon as possible. As we also explain on our implant metal page, the bone may have started to be lost long before any metal shows.

The fourth source is not the implant itself but its surroundings. Most bad breath comes from the coating on the back of the tongue, from gum pockets and decay in natural teeth, and from dry mouth. The NHS lists gum disease, decay and infection, dry mouth, tonsillitis, reflux and smoking among the causes of bad breath. If surgery has been carried out on an implant in the upper jaw or in the sinus area, a bad smell coming from the nose also brings the sinus to mind; we have explained this distinction on our page on a bad smell from the nose. That is why whether the smell is around a single implant or throughout the mouth is the first question to ask.

There is also a difference between removable and fixed prostheses. In a small follow-up study of 48 people fitted with an implant-supported prosthesis, a clinically unacceptable level of bad breath was measured in the majority of participants at most of the measurement points. In a cross-sectional study of 88 patients over the age of 65, the level of sulphur gases was highest in those wearing complete dentures and lowest in the fixed prosthesis and implant group; dry mouth and the use of many medicines were associated with a higher level of smell. Both studies are observational and small; they show an association, not a cause. The practical conclusion is this: an implant on its own neither solves nor creates the smell; cleanability and saliva flow are what decide it.

The pictures in the first list usually suggest build-up and ease within a few days with the right cleaning. If an item on the second list applies to you, inflammation or a mechanical problem around the implant should be considered and you should not wait for an appointment.

The order starts with danger: first the emergency signs are ruled out, then the source is narrowed down with safe checks that can be done at home, and last of all come the examination and X-ray.

1. 1

   Ask about the emergency signs first

   If there is major swelling in the mouth, face or neck, inability to open the mouth, difficulty breathing, speaking or swallowing, swelling in the eye or a problem with vision, the assessment is carried out in A&E; call 112. If none of these is present, move on to the next steps.

2. 2

   The interdental brush test at home

   Pass a clean interdental brush or superfloss around each implant and under the bridge separately, then smell it and look at its colour. Note which implant the smell and the blood come from. This simple test can narrow the source down to a single point and gives the dentist concrete information.

3. 3

   A week or two of regular cleaning, then check again

   Every evening, clean under the bridge with an interdental brush, superfloss and a water flosser if you have one, and clean your tongue too. In a small 30-day randomised trial, one of whose authors worked for a water flosser manufacturer, bleeding on probing decreased in 81.8% of the implants where a water flosser was used and in 33.3% of those where string floss was used. If the smell and bleeding ease markedly, the source was most probably build-up.

4. 4

   Look at the screw holes and the gum margin in the mirror

   Is the filling in the screw holes on the chewing surface of the bridge in place, and is there a dip or a dark colour? Is there redness, swelling or metal showing around the implant? Do not try to squeeze pus out by pressing; only look and take a photograph.

5. 5

   Examination: probing and bleeding

   The dentist looks for redness, swelling and pus around the implant, measures the pocket depth with a fine probe and checks whether there is bleeding. The 2017 consensus report defines health around an implant as the absence of redness, bleeding on probing, swelling and pus.

6. 6

   X-ray and comparison with the baseline record

   An X-ray is taken to see bone loss. The consensus report recommends taking a baseline X-ray and probing measurement after the prosthesis is fitted; when the new film is compared with this, it becomes clear whether the bone level has changed. Keep your old films and bring them with you.

7. 7

   Removing the bridge if needed

   Because a screw-retained bridge can be removed, the dentist can take it off when necessary and see its underside, the implant necks and the screw connections directly. If build-up, a worn area or a loose screw is found underneath, cleaning and correction can be done in the same session.

There is no single treatment for implant smell; what is done changes according to what the source is, and usually several steps are applied together.

The following are decisions that mask the smell but leave the source, or that delay the inflammation being noticed.

The time depends on the source. The sequence below is a general framework; the plan of the dentist who examines you takes priority.

1. The first days

   If the source is build-up under the bridge, the smell starts to ease in the first days after you begin regular cleaning. The gum may bleed for a few more days; this is not a reason to stop cleaning.

2. A week or two

   Smell and bleeding due to build-up should have eased markedly. If they have not, or if they persist at a single implant, the source may be in the pocket, the screw connection or the prosthesis design; an examination is needed.

3. After the screw hole or a loose screw has been corrected

   Once the source has been removed, the smell generally disappears quickly. If the screw loosens again, the reason is looked for in the bite or in clenching at night.

4. The weeks after peri-implantitis treatment

   After non-surgical treatment, reassessment is usually carried out a few weeks later. If the bleeding and pus have decreased, check-up intervals are set; if they have not, the next step is discussed.

The same complaint can correspond to very different procedures, from a short clean to replanning the implant. The items that determine the extent are these:

The source of the smell

Build-up under the bridge, the screw hole, a loose screw and inflammation around the implant each require different procedures.

Whether the bridge needs to be removed

Taking off a screw-retained bridge and inspecting its underside and the connections can mean a separate session.

The stage of the inflammation

While mucositis affecting only the gum is managed with cleaning, peri-implantitis with bone loss requires staged and sometimes surgical treatment.

Prosthesis design

An underside that cannot be cleaned can be corrected, or the prosthesis may need to be remade.