All about cavities between teeth

Cavities between teeth

Cavities between teeth are the second most common cavities seen in the dental practice. These cavities often affect two teeth at the same time.

Each tooth has five surfaces; outer, inner, chewing or biting, and two side surfaces. The cavities between teeth occur where two sides of adjacent teeth come in contact. These cavities are also known as interproximal (inter means in between and proximal means surface of teeth next to each other) cavities.

In this article, I will discuss how you get cavities between teeth, how they look, the ways to fix and prevent them .  

Why do you get cavities between your teeth?

Cavities between teeth occur in difficult-to-clean places where two teeth make contact. The sides of the teeth standing next to each other are slightly convex, and they contact each other at the maximum bulge. 

Two types of contacts appear between the teeth; closed and open. Close contacts are areas where floss passes with resistance. In other words, the floss enters the interdental space with a snap. However, in open contact, the floss passes between the teeth with no resistance. 

Close contacts are at a greater risk of tooth decay because of the food entrapment and plaque build-up between them. Moreover, they are more challenging to clean. Open contacts are, however, easier to clean and less prone to plaque build-up.

People generally believe that toothbrushing alone eliminates all the plaque from the teeth. Therefore, it is critical to understand that toothbrushes can’t reach the spaces between teeth. American Dental Association (ADA) recommends brushing teeth twice daily and flossing once daily to eliminate plaque and residual food particles from the mouth. 

Other factors responsible for cavities between teeth are increased intake of refined foods and insufficient fluoride in diet.

The nasty bugs feed on sugars and multiply in plaque and convert simple sugars to acid. Saliva prevents tooth decay from occurring. It washes sugar away from your mouth, stops acid from causing damage, fights bacteria, and gives minerals back to the teeth (during the early stages of tooth decay). 

The increased consumption and frequency of high-sugar foods and snacks increase the episodes of acid formation and the chances of bacteria eroding the outer protective enamel and initiating cavities.  

Statistics of flossing   

Based on NHANES, 2011-2014 stats, 36% of people over 30, 26% of men, and 37% of women floss daily. Moreover, 68% of people only floss once a week.

According to Delta Dental’s national public opinion poll, 20% of Americans never floss. 

How to know if you have cavities between your teeth?

The cavities between the teeth are most difficult to detect at home. They are hidden behind the gums and between the teeth. Primarily it affects the premolars and molars (back teeth) in both baby and adult teeth.

You cannot see a cavity between teeth unless the side of the tooth breaks down into a hole. Look for a black cavity between teeth. If you don’t see a black dot or spot on a tooth but experience pain or sensitivity in the tooth, it can be a symptom of a cavity on the side of the tooth. Consult a dentist and get a bitewing x-ray to see if it is related to tooth decay or gums. 

In advanced cases, a cavity between teeth appears as a hole between two teeth.

Can you get cavities between teeth
Look at the upper tooth with an black hole: A naked eye cannot see cavities between teeth unless the side of the tooth breaks down into a hole. If you don’t see a black dot or spot in a tooth, but you experience pain or sensitivity in the tooth. It can be a symptom of a cavity on the side of the tooth. Consult a dentist and get a bitewing x-ray to see if it is related to tooth decay or gums. 

Symptoms of a cavity between teeth

Following are the symptoms of a cavity between teeth: 

  • Sensitivity of tooth to hot or cold food or drink. 
  • Pain felt while eating.
  • Pain triggered by eating sweets.
  • Severe and lingering episodes of pain in the tooth.  
  • Pain in teeth, but you cannot pinpoint the tooth.
Can you get cavities between your teeth
Bitewing x-ray showing decay on the lower second tooth from the right: The black area shows the cavity on the side of the tooth. The neighboring tooth seems to be okay. The decay is quite extensive, but the tooth is intact. The patient came to the clinic complaining of pain in the tooth. The cavities between teeth are diagnosed mainly by pain or during a routine dental examination.

The development of cavities in between teeth is a relatively slow process. It takes several years to decades to appear on an x-ray. Hence it is less likely to be seen in kids’ permanent teeth. However, the surface of the first molar tooth facing the baby’s second molar is expected to be affected in kids.

How to detect a cavity between teeth?

Dentists carry out two standard steps to detect a cavity; visual examination and dental X-rays.

The mouth or visual examination is conducted with an explorer to see if there is any surface roughness or a hole in a tooth. 

Bitewings x-rays are the most powerful tool to confirm the cavities between teeth and their spread. Bitewings capture the crown portion of six teeth, three upper and three lower, when in a bite. 

How to fix cavities between teeth? 

There are several treatment options for a cavity in between teeth. The decision banks on the damage caused by decay and the affordability of the patient. These options are: 

Interproximal cavity filling (Filling between teeth)

This is the simplest and the most affordable treatment option for tooth decay. Small to moderate sized cavities confined to dentin are filled with composite and amalgam fillings. 

a Dental Inlay

Amalgam contains metals and has the property to expand and contract on exposure to hot and cold foods. Also, it doesn’t bond to the teeth, and therefore, after the removal of decay, the tooth is cut in a box shape with the walls tapering upwards to retain it. 

Amalgam expands and contracts on exposure to hot and cold foods and drinks, respectively. Large amalgam fillings may cause micro-cracks in the tooth from the expansion of a filling or allow fluid to seep into space between the tooth and filling upon contraction, causing secondary decay. This problem can be dealt with by placing an inlay instead.

An inlay is a filling prepared in the laboratory according to the prepared cavity’s shape and is bonded to the tooth.

A Dental Onlay 

In patients where the tooth has lost its two to three walls due to decay, an onlay can be a great option. Similar to an inlay, an onlay is fabricated in the laboratory, but it provides more coverage, i.e., it also covers the projections on the tooth called cusps. 

a Crown 

A Crown is an outside covering given on a tooth to prevent it from further breakage. It is given on a root canal treated tooth, which is quite fragile and prone to breakage. It is made in a laboratory and is an exact copy of a natural tooth crown. 

Root canal filling 

The invasion of bacteria to the pulp on an x-ray (with or without pain) indicates that infection has spread to the root canals (long tracks present in the root of a tooth) of a tooth and requires root canal treatment.

During root canal treatment, the decayed part of the tooth is removed with a drill, and access is made to the pulp. The root canals are cleaned and shaped with sharp needles called files and filled with long sticks called Gutta-percha (GP) sticks. A filling is placed over it, and the tooth is trimmed and covered with a crown. 


Extensive destruction of the tooth may require removal.

How to prevent cavities between your teeth?        

Specific measures to prevent cavities between teeth

The measures that prevent cavities between teeth involves:

  • Floss once a day to prevent cavities between teeth. Thread floss is most commonly used to remove plaque between the teeth.
  • If you hate flossing, use a water flossing device before the toothbrush to clean spaces between the teeth. It is proven to be more effective than thread flossing.
  • You can also use an interdental brush instead of a floss. It is available in different sizes. Ask your hygienist about the brush that is suitable for your teeth. Interdental brushes are not standardized, so please ensure to go for the brand that your hygienist recommends.
  • Avoid using toothpicks as they cause more damage to the gums.
  • Gum stimulator is another device to keep your gums healthy and interdental areas clean. Use the tip of the gum stimulator to massage your gums along the gum line. Slide the tip between your teeth to remove any plaque and food particles stuck between the teeth.
  • You can also use plaque-disclosing tablets occasionally to see how efficiently you are brushing and flossing. These tablets stains plaque deposits on the teeth.    
  • Interproximal grinding of baby molars (reducing the surfaces between the teeth to open the contacts) reduces the chances of cavities between teeth. 

General measures to prevent cavities

The following instructions help prevent cavities from developing:

  • Eating a healthy and well-balanced diet prevent cavities. Replace refined carbohydrates with fiber-rich complex carbohydrates. Nasty bugs feed on simple sugars from refined foods. By adding complex carbohydrates to your diet, you shift your mouth bacteria that aren’t cariogenic (cavity-causing). 
  • Regular brushing of teeth twice daily for two minutes with fluoridated toothpaste keeps cavities between teeth in check. Good oral hygiene reduces bad bugs from the mouth. 
  • If you live in a community where there is no water fluoridation. Add fluoride supplements to your diet.  
  • Chewing on sugar-free Xylitol gums after meals increase salivary flow. Saliva contains enzymes and minerals that gives minerals (calcium and phosphate ions) back to the demineralized teeth, a process known as remineralization.
  • Avoid tooth brushing for at least 20 min after a sugary meal because toothbrush bristles can damage softened enamel. 
  • Annual dental checkup helps in the early diagnosis and treatment of interproximal tooth decay. 

Frequently asked questions

Why do I keep getting cavities between my teeth?

Tight interproximal contacts are optimal for the health of the teeth and their associated structures. You can determine the tightness of your interproximal contacts by passing dental floss between teeth.

Cleaning between teeth is critical to the health of teeth. Flossing with a thread or water flosser is an effective way to clean spaces between teeth. You may be missing on flossing if you are getting cavities between teeth. The toothbrush can’t clean the sides of the tooth. If you have open contacts, you can also use interdental brushes. 

Crowding of teeth creates larger and unhealthy contact areas between the teeth, causing more plaque build-up. The larger contact areas resist floss to pass between the teeth. Orthodontic treatment restores healthy teeth contacts prolonging the life of the teeth. 

How much does a cavity between teeth cost?

Primarily, the cavities between teeth affect two surfaces of the teeth facing each other. The dentist will fill both teeth, and you will be charged for treating two teeth. The cost of treatment varies depending upon the scenario: 

  • Both teeth require filling. Often, one cavity is larger than the other. It may cost you $200-$600, depending upon the size of the cavity. 
  • One requires a root canal and the other needs filling. The root canal will cost $600-$1600, and the filling $200-$500 without insurance. 

Why do I feel pain between teeth after filling?

It is normal to have mild discomfort on chewing after filling a deep cavity. The tooth may take a couple of days to heal. If you experience severe pain or swelling in the tooth after filling, call the dental office. 

 The filling between my teeth fell out – What should I do?

Don’t panic if the filling between the teeth falls out. Get an appointment for a new filling. In the meantime, chew from the other side and brush your teeth to keep the tooth clean and prevent food impaction and bacterial growth.

Why do you get a cavity between bottom front teeth?

The cavity between the front bottom teeth is uncommon due to the continuous saliva production from the submandibular gland below the tongue. Some people don’t clean the inner surface of the lower front teeth, and the plaque deposits on this surface quickly calcify due to minerals-rich saliva poured below the tongue.

According to a study, tooth decay on the front teeth affects vegetarians more than non-vegetarians. It is most likely to be linked to the intake of fluoride-rich seafood. 

Moreover, saliva neutralizes the acid produced by oral bacteria acting on sugar substrates. When simple sugars are absent in the saliva, putrefaction replaces fermentation (converting sugar to acids), alkalinity replaces acidity, and no decalcification occurs. Putrefaction is caused by protein consumption, and therefore, people eating a protein-rich and low-carb diet are protected from tooth decay. 

Furthermore, people with lower front teeth crowding have more plaque deposits in the areas where teeth overlap, making them more prone to tooth decay. A regular toothbrush doesn’t effectively remove plaque from the problem areas, and a single tufted toothbrush may help in such cases. 

Mostly, a black spot between the bottom front teeth may be calcified early enamel tooth decay and require strict oral hygiene maintenance. However, a cavity between the front teeth requires a filling. Consult your dentist for a complete evaluation of the lower front teeth. 

What to do if there is a cavity between gum and tooth?

A cavity along the gum margin is often seen in people with receded gums. In patients with gum recession, the teeth appear longer. The exposed roots are not rigid as tooth enamel to survive in the harsh oral environment and, therefore, develop cavities at the gum margin. 

Root cavities are wider and shallow and don’t frequently involve tooth nerves. They appear as black, hard calcified tooth decay that require filling to restore it.

I have Pain between front teeth but no cavity – What is the reason for it?

If you experience pain between the front teeth but no cavity, the pain could be periodontal. The plaque accumulation below the gums may cause pain in the front teeth. In gum disease, the gums appear red to purple due to inflammation caused by irritation to plaque build-up.

You may also notice yellow tartar deposits along the gum margin. The inner surfaces of the front teeth are often missed and can cause plaque build-up. Please ensure to clean the inner surface of the front teeth. A toothbrush can’t clean the spaces between the teeth, and it is recommended to floss daily at night to remove all the plaque deposits. 

If you want to uncover the plaque deposits, you can use plaque-disclosing tablets. Plaque-disclosing tablets contain a dye that stains plaque so that you can clean the areas missed by a toothbrush. 

Why do I have a cavity between molars?

A cavity between two molars (permanent) is frequently seen in the dental practice. It is the second most common site affected by tooth decay.  

The permanent molars are less susceptible to cavities during the first year of eruption. The chances of getting cavities increase once the tooth fully erupts and becomes functional. 

Moreover, first and second baby molars are most prone to develop cavities and are treated with pulpotomy and pulpectomy procedures. 

Improper oral hygiene, lack of flossing, and a high-sugar diet are linked to the high prevalence of cavities between back teeth. 

Can you have a cavity without pain?

Yes, a cavity in its early stage does not cause any pain. Initially, a brown, or black spot may be seen on the tooth. However, the pain starts when the bacteria invade nerves in the tooth. 

Sensitivity on eating hot and cold food that disappears as the stimulus is removed is a sign of dentinal tooth decay or a moderaltely deep cavity in a tooth.

Do sensitivity in teeth means cavities?

No, sensitivity in the teeth isn’t always related to the cavities. Frequently, it occurs due to environmental exposure to the roots of the teeth. The root surface isn’t covered by a tough enamel but is enveloped in a thin cellular cementum that can not sustain the harsh oral environment.

How long does it take for a cavity to hurt?

Pain in the tooth occurs when the infection spreads deep into the tooth. Everyone shares a different experience. It usually takes months or even years for the disease to reach the inner pulp. However, its progression is directly related to your dietary habits and oral hygiene practices. 

Are all black spots on teeth cavities?

No, all the black spots on the teeth are cavities. The black spots on the teeth can be stains produced by chromogenic bacteria. The chromogenic strains of bacteria produce hydrogen sulfide that reacts with iron in the saliva forming insoluble iron deposits and blackening of teeth.

Other causes of teeth staining are:

  • Tarr from smoking tobacco
  • Frequent habit of drinking tea and coffee.
  • Excess intake iron tonics
  • prolong use of Chlorhexidine mouth rinses.
  • Habit of betel nut chewing

Teeth staining usually involves several teeth in the mouth, but a tooth cavity involves one or two teeth.

Can you floss after a filling between your teeth?

Yes, you can floss after a filling. There are two types of composite filling materials used in dentistry; light cured and chemically cured materials. The light cured materials are most frequently used to fill the cavities. They completely set on UV light exposure used by dentists to cure it.

So you can floss anytime after getting back from the dental office. Amalgam fillings may take 24 hours to attain their maximum strength and is best to wait for 24 hours after an amalgam filling for it to fully mature. 

Are cavities always visible?

No, all the cavities are not visible, especially the cavities between teeth are diagnosed late when they cause pain or the tooth breaks down. They are often diagnosed during routine dental examinations. However, cavities on other surfaces can be identified earlier by a black or brown spot. 


The cavities between teeth are common among adults and frequently occur in people with tight contact between the teeth. These surface favors plaque deposition due to reduced visibility and lack of flossing.

The bitewing x-rays aid dentists in diagnosing and planning an appropriate treatment plan. Regular dental visit helps detect and treat early decay. 

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