Cavity between teeth (All you need to know)

cavity between teeth
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A cavity between teeth occurs below the point where two teeth make contact. This type of tooth decay or caries is most difficult to detect. It is hidden behind the gums and between the teeth. Mostly it affects the back teeth (premolars and molars). This type of caries or tooth decay is known as interproximal caries or tooth decay.

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.

What causes a cavity between teeth

Tooth decay is a diet related disease. It occurs in places that are difficult to clean and prone to plaque buildup like the sides of the teeth where two teeth make contact. The bad bugs that feed on sugars, multiply in the plaque and convert simple sugars to acid.

The saliva prevents tooth decay from occurring. It washes away sugar out of your mouth, stops acid from causing damage, fights bacteria and can repair the early stages of tooth decay by restoring the tooth mineral. 

The increase consumption and frequency of sugary foods and snacks increase the episodes of acid formation and increase the chances of bacteria to breach the outer enamel 1. It is known that enamel is the hardest structure in the human body (harder than the bone) and is 90% composed of mineral salts. Enamel when exposed to acid dissolves the minerals and softens it. Bacteria enters the tooth through this demineralized soft area.

Dentin (the next layer of the tooth) is porous, less hard than enamel and easy for the bacteria to destroy. The whole process takes months and even years to occur, reach the inner pulp and ultimately cause pain.

How do I know if I have a cavity between teeth?

The cavities between teeth cannot be seen by a naked eye. If you don’t see a black dot or hole in a tooth but you have the following symptoms, you must consult a dentist and get a bitewing x-ray to see if it is related to tooth decay or gums.

  1. Sensitivity to hot or cold food.
  2. Pain felt while eating.
  3. Episodes of severe pain in tooth.  
  4. Pain in teeth but you cannot tell which tooth is it

Treatment options for cavity on the side of tooth

There are several treatment options for a cavity in between teeth. The dentist decides on the basis of sound tooth structure left after the decay and the affordability of a patient. These options are:


The simplest and the most affordable treatment option for tooth decay limited to dentin is a composite or an amalgam filling. Small to moderate size cavities are ideal for these filling materials.

Inlays – A better option for a cavity between teeth

Amalgam fillings have a property to expand and contract on exposure to hot and cold foods. It doesn’t bond to the teeth but the cavity is specially designed for the filling to stay in place in a box shape whose wall gets narrow as it reaches the top.

Large silver fillings may crack a tooth from the expansion of filling or allow fluid to seep into space between the tooth and filling upon contraction and cause secondary (another) decay. However, this problem can be dealt by placing an inlay instead.

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

Onlays – An Ideal for a large cavity between teeth

Onlay is a partial crown bonded to a tooth. Sometimes a tooth is destroyed from the side and top or in few some cases both sides of the tooth are lost. These cases are good candidates for onlays. They are made of gold, ceramic or composite.


Crown is an outside covering given on a tooth to prevent them from further breakage. It can be given even if only 2mm of natural tooth that is visible in the mouth is left unaffected by decay. It is made in a laboratory and is an exact copy of a natural tooth crown.

Root canal treatment for cavity between teeth

The invasion of bacteria to the inner pulp on an x-ray (with or without pain) indicates that infection has spread to the root canals of a tooth and requires cleaning and shaping of root canals.

First, dentist removes the decayed part of tooth with a drill and makes access opening to the pulp. Second, the root canals are cleaned and shaped with sharp needles called files and are filled with long sticks called Gutta-percha (GP) points. 

Finally, an amalgam or white filling replaces the lost dentin over it. The whole treatment is known as root canal treatment

Tooth Extraction

Grossly decayed tooth where decay has spread to the root of the tooth requires removal. However, an implant or a bridge placement at site of tooth removal restores the lost tooth.

How to prevent cavity between teeth?

Following measures help decrease the incidence of caries or cavities between teeth:

  • Eating a healthy and well-balanced diet prevent cavities. Replace refined carbohydrates with fiber rich complex carbohydrate. Bad bugs feed on simple sugars from refined foods. By adding complex carbohydrates to your diet, you shift your mouth bacteria that aren’t cariogenic (caries causing).
  • Make a habit of brushing your teeth twice a day for two minutes and flossing once daily. Good oral hygiene reduces bad bugs from the mouth.
  • Use of fluoridated toothpaste protects teeth against tooth decay. Using fluoride toothpaste with 1.5% arginine affects the oral environment positively in adults with caries, by increasing plaque and salivary pH and to neutralize acids.
  • Chewing on sugar-free Xylitol gums after meals increase salivary flow. Saliva contains enzymes and minerals that aid in giving 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 brushing could potentially damage softened enamel.
  • Drinking some plain water to wash sugars out of mouth after a sugary food or drink .
  • Annual dental checkup helps in early diagnosis and treatment of the tooth decay.


Cavity between teeth is the second most common tooth surface affected by tooth decay because of the reduced visibility and difficulty to clean. X-rays aid dentists in detecting the extent of decay and to plan an appropriate treatment plan. Regular dental visit helps detect and treat the early decay.


  1. Atkinson, F. S., Khan, J. H., Brand-Miller, J. C., & Eberhard, J. (2021). The Impact of Carbohydrate Quality on Dental Plaque pH: Does the Glycemic Index of Starchy Foods Matter for Dental Health?. Nutrients13(8), 2711..

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