Worldwide, approximately 3.6 billion people have dental caries in their permanent teeth.
In baby teeth, it affects about 620 million people or 9% of the population.


Tooth decay, also known as dental caries or cavities, is the breakdown of teeth due to acids made by bacteria.

The cavities can be several colors from yellow to black.

Signs and symptoms:

They can vary depending on the expansion of the cavity:

  • Pain or a toothache that happens without warning
  • Sensitive teeth
  • Pain when you eat or drink sweet, hot, or cold things
  • Holes or pits in your teeth
  • Black, white, or brown tooth stains
  • Pain when you bite down
  • Tender to pressure
  • Bad breath and foul tastes


Tooth decay is caused by biofilm (dental plaque) lying on the teeth. Certain bacteria in the biofilm produce acid in the presence of fermentable carbohydrates such as sucrose, fructose, and glucose

Four things are required for caries to form: a tooth surface (enamel or dentin), caries-causing bacteria, fermentable carbohydrates, and time.

Risk factors:

  • Clingy foods and drinks: Foods like sugar, soda, milk, ice cream, cereal, and chips are more likely to stay put and cause decay.
  • Poor brushing: When you don’t brush your teeth after eating and drinking, plaque and decay have a chance to form.
  • A lack of fluoride: This mineral, found in toothpaste, mouthwash, and some tap water, helps to prevent cavities and can reverse early tooth damage. 
  • Eating disorders: When you throw up over and over, stomach acid can dissolve teeth enamel, which may lead to cavities. 
  • Acid reflux disease: This condition forces stomach acid into your mouth and wears down your teeth, causing cavities.
  • The use of tobacco may also increase the risk for caries formation. Some brands of smokeless tobacco contain high sugar content, increasing susceptibility to caries.
  • Poverty is also a significant social determinant for oral health. Lower socioeconomic status is often associated with dental caries.

*Risk factors include conditions that result in less saliva such as:

  • Diet high in simple sugar.
  • Diabetes mellitusdiabetes insipidus, Sjögren syndromesarcoidosis, and medications that decrease saliva flux such as antihistamines and antidepressants.
  • Stimulants, most notoriously methylamphetamine, also occlude the flow of saliva to an extreme degree. This is known as “meth mouth”. Tetrahydrocannabinol (THC), the active chemical substance in cannabis, also causes a nearly complete occlusion of salivation, known in colloquial terms as “cotton mouth”.
  • Radiation therapy of the head and neck may also damage the cells in salivary glands, somewhat increasing the likelihood of caries formation.

Reduced salivary flow rate is associated with increased caries since the buffering capability of saliva is not present to counterbalance the acidic environment created by certain foods.

*There are certain diseases and disorders affecting teeth that may leave an individual at a greater risk for cavities:

  • Molar incisor hypomineralization, which seems to be increasingly common.
  • Amelogenesis imperfecta.
  • Intrauterine and neonatal lead exposure promote tooth decay.


The presentation of caries is variable.

Initially, it may appear as a small chalky area (smooth surface caries), which may eventually develop into a large cavitation. Sometimes caries can be directly visible.

The inspection must include a good light source, dental mirror, and explorer.

However other methods of detection such as X-rays are used for less visible areas of teeth and to judge the extent of the destruction. 

Lasers for detecting caries allow detection without ionizing radiation and are now used for the detection of interproximal decay (between the teeth).

Early caries without cavitation is often diagnosed by blowing air across the suspect surface, which removes moisture and changes the optical properties of the unmineralized enamel.

Careful, in cases where a small area of the tooth has begun demineralizing but has not yet cavitated, the pressure from the dental explorer could cause a cavity.


Since the carious process is reversible before a cavity is present, it may be possible to arrest caries with fluoride and remineralize the tooth surface.

Once a lesion has cavitated, remineralization is much more difficult and a dental restoration is usually indicated after removing the cavity.

Restorative materials include dental amalgam, composite resin, porcelain, and gold.

When the decay is too extensive, there may not be enough tooth structure remaining to allow a restorative material to be placed within the tooth. Thus, a crown may be needed.

Crowns are often made of gold, porcelain, or porcelain fused to metal.

For children, preformed crowns are available to place over the tooth. These are usually made of metal.

In certain cases, endodontic therapy may be necessary for the restoration of a tooth.

Endodontic therapy, also known as a “root canal”, is recommended if the pulp in a tooth dies from infection by decay-causing bacteria or from trauma.

An extraction can also serve as a treatment for dental caries. The removal of the decayed tooth is performed if the tooth is too far destroyed from the decay process to effectively restore the tooth.


Oral hygiene

1.Tooth brushing and flossing

A toothbrush can be used to remove plaque on accessible surfaces. 

Dental floss removes plaque from areas between the teeth.

American Dental Association Council suggest that for children <3 years old, caregivers should begin brushing their teeth by using fluoridated toothpaste with an amount no more than a smear. Supervised toothbrushing must also be done to children below 8 years of age to prevent swallowing of toothpaste.

2.Professional hygiene care consists of regular dental examinations and professional prophylaxis (cleaning). Sometimes, complete plaque removal is difficult, and a dentist may be needed.

3.Alternative methods of oral hygiene also exist around the world, such as the use of teeth cleaning twigs such as miswaks in some Middle Eastern and African cultures. But, there is some limited evidence demonstrating the efficacy of these alternative methods of oral hygiene.

Dietary modification

Chewy and sticky foods tend to adhere to teeth longer. However, dried fruits such as raisins and fresh fruit such as apples and bananas disappear from the mouth quickly and do not appear to be a risk factor.

For children, the American Dental Association and the European Academy of Paediatric Dentistry recommend limiting the frequency of consumption of drinks with sugar and not giving baby bottles to infants during sleep. Parents are also recommended to avoid sharing utensils and cups with their infants to prevent transferring bacteria from the parent’s mouth.

Calcium, as found in food such as milk and green vegetables, is often recommended to protect against dental caries. 

Fluoride helps prevent decay of a tooth by binding to the hydroxyapatite crystals in enamel.

Xylitol is a naturally occurring sugar alcohol that is used in different products as an alternative to sucrose.

Other measures

The use of dental sealants is a means of prevention.

A sealant is a thin plastic-like coating applied to the chewing surfaces of the molars to prevent food from being trapped inside pits and fissures. 

Sealants are usually applied on the teeth of children, as soon as the teeth erupt but adults can also receive them if not previously performed. Sealants can wear out and fail to prevent access to food and plaque bacteria inside pits and fissures and need to be replaced so they must be checked regularly by dental professionals.


Inflammation of the tissue around the tooth.

Tooth loss.


Abscess formation.


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