The tooth is made up of different layers. The outermost layer is the enamel and cementum, followed by the dentin and pulp.
There are different stages of tooth decay. The bacterial attack starts from the enamel and then progresses inwards.
Dental decay is small in the beginning and is not visible to the naked eye. After reaching the innermost layer, tooth decay can cause severe damage to the tooth.
Dental caries, also known as tooth decay, is defined as a microbial disease of the calcified tissues of the tooth, characterized by demineralization of the inorganic portions and destruction of its organic structures.
Acids formed due to the fermentation of dietary carbohydrates by oral bacteria lead to progressive decalcification of the tooth structures.
This leads to subsequent disintegration of the organic matrix.

Table of Contents
The different stages of tooth decay
It is important to understand the stages of tooth decay so that tooth decay can be prevented and treated. The stages are as follows :-
Stage 1: Demineralisation
During the development of caries, a large variety of acids are produced in the oral cavity due to the bacterial fermentation of dietary carbohydrates.
Metabolism of carbohydrates produces organic acids, which result in a highly localized drop in the pH.
A decrease in the pH below 5.5 causes demineralization of tooth surfaces. The enamel becomes weak and is at the risk of chipping off.
This demineralization is visible as chalky white areas on the surface of the tooth.
If the tooth decay is identified at this point , steps can be taken to stop the decay and to remineralize the structure.
Following the correct brushing technique and using fluoridated toothpaste and topical fluoride can help in remineralizing the enamel.
Stage 2: Enamel decay
At this stage, the enamel breaks down due to bacterial attack, and the dentinal layer gets exposed. Tooth decay cannot be reversed at this stage.
Due to the exposure of the dentin, patients may experience sensitivity or pain. Discoloration will also be observed.
A dentist should be consulted at this stage to stop further spread of decay. Treatment for enamel decay may include fillings or crowns depending on the severity and location of the issue.
Stage 3: Dentin decay
If the decay in the enamel is not treated, the enamel weakens.
After the breakdown of enamel, dentin gets exposed and infected.
The spread of decay is faster in the dentin because of its porous nature. The pain also intensifies when the decay reaches the pulp.
Decay in the dentin is sharp and painful. Dentin decay should be treated as soon as possible.
A dental filling is needed to restore the tooth.
If the infected dentin is left untreated, the infection will reach the pulp.
Stage 4: Dental pulp infection
The dental pulp forms the innermost layer of the tooth. It is made up of nerves, blood vessels, and connective tissue.
The pulp provides nutrition and maintains the health of the tooth.
The infection of the pulp is excruciating and uncomfortable.
The bacterial invasion of the pulp kills the blood supply and innervation of the tooth.
Root canal treatment is the treatment of choice for an infected pulp.
Post the root canal treatment, a crown should be cemented on the tooth to protect it from further decay.
Stage 5: Abscess formation
If the infected pulp is not treated by root canal treatment, the infection from the pulp will spread to the surrounding gums and bone.
This will result in inflammation and swelling of the surrounding tissues.
Pus formation may be observed in the gums and alveolar bone.
Abscesses need urgent attention because they have an impact on general health too. Antibiotics are prescribed for treating dental abscesses, followed by root canal treatment.
If the severity of tooth destruction is excessive, then the tooth needs to be extracted.
How to prevent tooth decay?
Tooth decay should not be ignored. A natural tooth can be saved by treating it at the right time.
A tooth is an organ of the body which is unable to repair itself.
Undertaking preventive measures to control the start and spread of infection is essential.
Methods to avoid tooth decay and maintain healthy oral hygiene :
- Brushing twice a day daily
- Rinsing mouth post every meal
- Flossing daily
- Visiting the dentist every six months
Taking care of teeth and gums is essential. It helps to prevent tooth decay and gum recession. Maintenance of good oral hygiene helps to prevent and control the different stages of tooth decay.