7 Causes of Bad Breath: Tooth Decay Smell, Cavities, and More

man with bad breath
If you suffer bad breath the cause is most likely in your mouth. Conditions like tooth decay smell, cavities, or gum disease can all be bad breath causes.

Troubled with bad breath? It’s an embarrassing and frustrating problem. Luckily there are many easy solutions to chronic bad breath. One of the first ways you should look for a cure for bad breath is to see your dentist. Bad breath is often caused by oral diseases.

Ninety percent of cases of bad breath, or halitosis, actually originate in the mouth. The first port of call to cure bad breath is to see your dentist.

Bad breath causes that begin in the mouth:

  • Tooth decay smell and cavities
  • Failed dental work
  • Gum disease
  • White-coated tongue
  • Dry mouth (or low salivary flow rate)
  • Oral infections
  • Peri-implant disease
  • Oral cancer

Most dental diseases are caused by imbalances in your oral microbiome. In most cases, they are due to an overgrowth of ‘harmful’ bugs that release metabolites. This produces an odour that can be smelt on the breath.

 

Bad Breath Cause #1: Tooth Decay Smell and Cavities

Bad breath may signal tooth decay smell.  Initially, bacteria effect the hard outer enamel of your tooth. As bacteria burrow deeper into the softer inner tooth, the species causing the decay change.  E. faecalis, commonly found in the colon, and A. actinomycetemcomitans become prominent. Their presence changes the products released into your mouth.

 

Bad Breath Cause #2: Failed dental restorations

Have you had dental restorations, crowns or bridges? Decay or food traps beneath them may cause bad breath. You may notice a bad taste too. Visit your dentist, who will investigate with x-rays or radiographs to reveal underlying conditions. This cause of bad breath can not be discarded, it is as common as tooth decay smell and the ones that follow.

 

Bad Breath Cause #3: Gum disease

Gum disease progresses through different stages, which may all cause bad breath.  Let’s look at the stages of bleeding gums and gum disease.

 

Early-stage gum disease: ‘Food Caused’ bad breath

In early stage gum disease or bleeding gums, a buildup of plaque and calculus occur. This eventually causes enlarged gum ‘pockets’ (spaces between your teeth and gums). Food debris becomes trapped in the spaces between the teeth and gums. Bacteria find and eat these trapped food particles which can cause bad breath.  Foods that contain dense proteins such as meats, dairy or fish, are broken down to pungent volatile sulfur compounds (VSCs).

 

2 types of early stage ‘food caused’ bad breath

  • Rotten Eggs: Cysteine breaks down to hydrogen sulfide, which smells like ‘rotten eggs’.
  • Rotten Cabbage: The protein methionine (commonly found in meat, eggs, and dairy) breaks down to methyl meth mercaptan, which smells like rotten cabbage.

As gum disease worsens, the bacteria in these pockets become more harmful. A particular type, called anaerobes, thrive in the absence of oxygen. Their presence is a sign that your gum disease is later stages may also cause bad breath.

 

Late stage gum disease: ‘Blood caused’ bad breath  

As gum disease progresses, both the pH and oral microbiome changes. In this stage, bad breath can worsen. Increased inflammation from bleeding gums provides a nastier set of ‘anaerobic’ bacteria access to blood and immune cells. These bugs thrive on an alkaline pH in the gum pocket. They then feed blood and immune cells.

Bad breath is now caused less by food breakdown and more by a mixture of decaying immune and blood cells. It means that the smell changes too.

 

2 types of ‘blood caused’ bad breath

  • Metallic smell or taste: Initially, as the iron in the blood breaks down, you may notice a metallic smell or taste.
  • Putrid or ‘rotten smell: As gum disease worsens, or is left untreated, the smell becomes far more putrid smelling.

In these more serious cases of gum disease, periodontal treatment is often helpful in halitosis (severe bad breath). Removal of the harmful microbiota may only be achieved by dental root planning. It’s important to identify the root cause of your bad breath. In order to heal gum disease and bad breath you need to probiotic bacteria.

 

Bad Breath Cause #4: Tongue Coating

In some cases, neither your teeth or gums are unhealthy, or the cause of your bad breath. Instead, the culprit is your tongue.

Your tongue’s bumps and grooves are ideal for trapping debris and bacteria.

Just like bacteria like to hide in pockets in your gums, they also like to hide in the crevices of your tongue. A tongue coating is similar to dental plaque and can cause bad breath.  The coating appears on the top surface of the tongue. It’s usually towards the back of the mouth, near the throat.  It looks like a pale, white coating.

Tongue coating can be a mixture of sulfur compounds and mucus. It can also include food particles, coffee or tea, and bacteria. If it’s not cleaned away every 24 hours, bacteria can begin breaking these products down and cause bad breath.

In the same way, gum disease can cause bacterial imbalance, so can your tongue coating.  As anaerobic bugs infiltrate, they cause bad breath.  Many studies have shown that removing this tongue coating reduces bad breath and VSC levels.

If you suspect your tongue is causing your bad breath, try cleaning the dorsum (top surface) of the tongue regularly with a tongue cleaner.

 

Bad Breath Cause #5: Dry mouth or low saliva  

Saliva performs many functions, including balancing minerals and aiding the digestive system and immune system.

Saliva contains immune factors known as IgA and other factors called lysozymes. These help healthy digestion and also prevent the buildup of harmful bacteria. In a healthy mouth, saliva helps to maintain the oral pH at slightly acidic. This prevents harmful bacterial buildup and the breakdown of proteins such as cysteine and methionine. These proteins create sulfur containing compounds (VSCs) and cause bad breath.

When your salivary flow rate is low, you lose the benefit of saliva’s cleansing abilities. The environment in your mouth becomes alkaline, allowing the growth of harmful bacteria and those that break down VSCs.

So, what might affect your salivary flow rate and cause a dry mouth?

Diseases that affect the salivary glands, such as Sjogren’s Syndrome, certain medications and breathing through your mouth may all cause dry mouth.

The most common type of bad breath caused by saliva flow problems is ‘morning breath’ – bad breath that’s only present when you wake up. This is usually due to decreased production of saliva while you are asleep but may also indicate you are breathing through your mouth during the night.

 

Bad Breath Cause #6: Oral Infections

 

Dry Socket

After a tooth extraction, a blood clot normally forms to begin the healing process. Dry sockets occur when the blood clot is lost from the socket. This can happen because of negative pressure in the mouth, perhaps from sucking on a straw or smoking, which prevents clot formation. The resulting exposed wound may be very painful – and more painful than the original toothache.

This condition can cause both a bad taste and bad breath due to trapped food debris and bacteria. One of the most common signs of a dry socket, other than gum pain, is bad breath.  Large dry sockets can take weeks or even months to heal completely. They usually require irrigation after every meal to prevent food particles from lodging in them and festering.

 

Pericoronitis

When teeth are erupting in the gums, the slightest opening in your gum can allow saliva and bacteria into the space around the tooth. If the space can’t cleanse itself, you may find yourself with an infection.

This condition is called pericoronitis (infection in the soft tissues around the crown of the tooth).  It may cause just mild pain or a dull ache, but sometimes the area may become very painful and swollen. If your gum is red and inflamed around a tooth that hasn’t fully erupted, and you have a bad taste in your mouth and bad breath, you may have pericoronitis.

 

Peri-Implant Disease

In peri-implant disease,  inflammation occurs in the soft tissues around a dental implant. Generally, peri-implant mucositis (inflammation of gums) is a precursor to peri-implantitis where there is bone loss around a dental implant. If you’ve had an implant and have bad breath or an unpleasant taste in your mouth, it may be a sign of peri-mucositis. You should see your dentist straight away.

 

Mouth Ulcers

Mouth ulcers can occur on the lips, tongue or, more commonly, the inside of the cheeks.  They will look swollen and may be white, red, yellow or gray.  It’s possible to have more than one mouth ulcer at a time and they may spread or grow.

Mouth ulcers can occur due to:

  • Physical damage: wear and tear, biting your cheek or tongue, or puncture wounds caused by foods with sharp edges such as crisps.
  • An allergic reaction or auto-immune system response to chemical or biological agents. The primary damage happens underneath the surface, causing cells to die within the connective tissue. When the damage reaches the surface, the ulcer seems to appear from nowhere.
  • Inflammatory or infectious disorders, and cutaneous, gastrointestinal, and hematological diseases.

 

Bad Breath Cause #7: Oral Cancer

Remember, as you have already seen, there are many oral causes of bad breath. These also include systemic causes not covered here. You shouldn’t presume that bad breath means you have oral cancer, but be aware that it’s a potential if uncommon, cause of bad breath.

Often, oral cancer is only detected in its later stages, so if you have persistent bad breath or experience any of the following symptoms, visit your dentist immediately.

Signs of oral cancer:

  • A lump or thickening in the cheek
  • A white or red patch on the gums, tongue, tonsil, or lining of the mouth
  • Persistent mouth ulcers
  • A lump in the neck
  • Weight loss

 

Oral Causes of Bad Breath Screening Questionnaire

Most cases of bad breath are caused by disease in the mouth. Often it can be improved by a visit to the dentist and improved oral hygiene. However, sometimes bad breath originates from a problem elsewhere in the body (like the nose or the digestive system).

So, how can you tell if your bad breath originates from your mouth? Or should you be visiting your doctor?

If your bad breath is more likely to originate in your mouth if:

  • It is improved by the regular use of mouthwash (I don’t recommend mouthwash for bad breath)
  • It is improved by better oral hygiene and tongue brushing.
  • The odor does not exit from the nostrils.
  • The odor intensifies for an observer when you begin to talk, indicating that the odor is
  • coming from the mouth rather than the nose. Your pharmacist may ask you to count to 20 while they check your breath for this.
  • The odor worsens if the mouth becomes dry, as the buffering effect of saliva is lessened
  • and non-sulfur containing gases are liberated when oral tissue is dry.
  • You lick your hand and there is a detectable odor when the saliva dries.
  • You scrape the back of the tongue gently with a disposable plastic spoon and the residue on the spoon smells the same as your breath.

If you have bad breath, the first step you should take is to book in to see your dentist.

Let us know your experience with bad breath in the comments below.

For more information on Dr. Lin’s clinical protocol that highlights the steps parents can take to prevent dental problems in their children: Click here.

Want to know more? Dr Steven Lin’s book, The Dental Diet, is available to order today. An exploration of ancestral medicine, the human microbiome and epigenetics it’s a complete guide to the mouth-body connection. Take the journey and the 40-day delicious food program for life-changing oral and whole health.

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12 Responses

  1. I smell horrible, i brush, floss, use bottles of mouthwash a month, i have several rotten teeth, the smell comes out of my nose, ears, and eyes. People gag and vomit when i talk to them, I’m a 34 year old single Mom of 4. I cant go to the Dentist. Ive tried everything to get rid of the smell, von you recommend something otc and cheap?

  2. Hi There. I recently went out with a guy and really liked him but his breath was unusually bad each time. It was not “typical’ bad breath. It was like and “old person” if that makes sense? Hard to describe but sickly sweet (in a bad way). He was otherwise healthy and teeth looked good. I feel bad but I can’t really tell him without hurting his feelings. I can’t imagine that he hasn’t been told. It is a really weird odor and I don’t think its a quick fix kind of problem. It is something that has been lingering in his mouth for a long time. Any ideas?

  3. I’m in my 40’s single no kids. Since my mid 20’s I’ve had complaints about my breath. Ironically it started after a surgery I had that included surgery to my abdomen. Before then I had no complaints. I brush, floss, see my dentist even talked to him about it. I’ve been to a gastroenterologist (had H. Pylori), went to ENT (had tonsils shaved down, tonsil stones) , tried Therabreath, cut out certain foods etc. I’ve tried everything and sometimes I get so depressed and understand why no one wants to be around me. My hygienist says my hygiene is great. I don’t know what else to do. I have a few crowns and one came off the tooth under it is decayed, could that be it? It’s like the smell is coming from my lungs. I’m lost and want to give up. Please help!!!

    1. Hi Tabitha,

      Digestive problems can be very persistent. If you had bad breath, I would suspect small intestine bacterial overgrowth (SIBO). You can get breath tests that specifically test the gut. https://www.drstevenlin.com/gut-breath-the-digestive-system-and-bad-breath-causes/

      Checking your Vitamin D levels is also very important. You will also want to get checked for H.pylori infection (happens in both digestive system and mouth) https://www.drstevenlin.com/gerd-symptoms-h-pylori-begin-oral-microbiome/

      Also have your IgG food intolerance test done if possible and check your vitamin D status.

      Probiotics may also assist.
      https://www.drstevenlin.com/can-oral-probiotics-cure-bad-breath/

      Hope this helps!

      Chelsea
      Community Manager
      http://www.dstevenlin.com

  4. Hi,
    I have three dental bridges and they are all meta bridges. When I talk to people they always either cover their nose or take a few steps back. They try to do it so I don’t notice but I do.
    Could the bridges cause me to have bad breath? I brush, floss, scrape my tongue, cheeks and clean the roof of my mouth. Any suggestions would be appreciated.
    Thanks,

  5. hello I recently got one of my molars removed due to decay but since then I have been having a bad odor come out and also s bad taste from the area where the tooth was removed…what could be the problem? and its solution?

  6. got my tooth (wisdom tooth) pulled out, was quite the experience. its been three days and ive had no pain, just a very foul taste in my mouth. im not sure what the hole is supposed to look like, ive been avoiding eating from that side but food eventually goes there and i use mouthwash to flush it out. how can i get rid of the taste

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