Tooth decay stages: From cavity to serious complications

Tooth decay is one of the most common diseases in the world. It has been a real problem for the last 10,000 years when our diet became based on sugars. Tooth decay is the result of the mineral dissolution in the tooth due to the acidity released by the bacteria.
Discover the different stages of tooth decay and the treatments available.

How does tooth decay progress?

Did you know that?

The enamel that covers the tooth is the hardest tissue in our body. It contains the highest percentage of minerals (at 96%).

enamel rods

Under the microscope, we can see that enamel contains multiple segments called enamel rods. These rods are composed of closely packed oblong crystals that are about 1,000 times smaller than a strand of hair. Their job is to ensure the rigidity of the rods and strengthen the enamel.
In short, the juxtaposition of the crystals will form the rods, which themselves will form the enamel.

Although enamel is the hardest tissue, it has a weakness, as do all minerals.

palatal expander

In an acidic environment, the chemical bonds that form the hydroxyapatite crystals will break, creating small cavities. These cavities will fuse to form a superficial lesion called demineralization. The enamel can't regenerate, but the decay at this stage can be stopped.
If left untreated, demineralization can turn into a cavity that is irreversible.

Enamel decay will continue to progress deeper into the layer below: the dentin.
Dentin is also a mineralized tissue, but it is less dense than enamel, resulting in rapid destruction and progression to the pulp.
Unlike enamel, dentin can regenerate, the treatment at this stage aims to preserve the tooth by a dental filling.

The decay will continue to progress to reach an innervated and vascularized tissue: the pulp. At this stage, different complications can occur.

Tooth decay stages

Tooth decay goes through 4 stages:

Enamel stage

superficial stage

Decay first affects the enamel, which is the outermost layer covering the tooth.
At this stage, the decay can be easily stopped. The lesion is superficial enough to respond well to remineralization treatments.
When enamel decay has set in, you will not feel any pain which makes it difficult to spot, but you may notice whitish or brownish spots that show the signs of demineralization.
Untreated, demineralization may evolve into a cavity.

Dentin stage

Dentin is in direct contact with the pulp.
When dentin is affected, your tooth will be sensitive to cold and pressure.
Dentin decay is quite deep, so it is inaccessible to topical remineralization treatments. The treatment aims to eliminate the decay and replace the destroyed tissue with a filling to protect the pulp.
Dentin decay progresses rapidly because it is less resistant than enamel. This is a real threat to the pulp.

Pulp stage

deep stage

The pulp is an innervated and vascularized tissue located in the center of the tooth. Once affected, inflammation will occur resulting in pulpitis.
Immune reactions within the pulp will increase the pressure inside the tooth causing severe pain.
If the infection persists, the blood vessels supplying the tooth will become congested resulting in pulp death or necrosis.
This is also the stage where complications occur, including dental abscess, cellulitis, sinusitis, septicemia and endocarditis.


If left untreated, pulpitis can lead to serious complications, the most common is dental abscess. Dental abscesses form under the tooth and cause swelling, redness and pain on the gums that can spread to the rest of the jaw.

final stage

Other complications include:

  • Cellulitis: In an advanced stage, the infection can spread to the external tissues of the face and neck and cause swelling, redness and heat sensation.
    Facial cellulitis must be treated as soon as possible because it can progress to the diffuse stage which can be life-threatening.

  • Sinusitis: The roots of the upper molars are very close to the maxillary sinuses. Dental infection can contaminate them and lead to sinusitis of dental origin.

  • Endocarditis: Bacteria from the dental abscess can reach the heart through the bloodstream and lead to bacterial endocarditis.

  • Septicemia: Bacteria involved in pulpitis can reach the bloodstream and affect other organs including the kidneys, lungs, liver.
    People who have diseases related to one of the organs are most at risk.

Treatment options

The treatment of tooth decay depends on its stage. The preservation of the tooth must be the priority. Keep in mind that extraction is the last option, considered only if the initial treatment has failed.

When decay is limited to the enamel, it can be reversed by remineralization procedures and good oral hygiene. Fluoride bind to the crystals that form enamel and make them stronger and more resistant, which makes it possible to stop the progression of tooth decay. It has also anti-bacterial properties and prevents the formation of dental biofilm.
Among the different forms of fluoride applications:

  • Brushing twice a day with fluoride toothpaste.
  • A fluoridated mouthwash.
  • Fluoride gel and varnish

When remineralization procedures have failed or if the cavity has reached the dentin, your dentist will choose a conservative treatment. He will first remove decayed tissue. If the cavity is deep, he will put a dental material in contact with the dentin to promote its remineralization. The cavity will be filled with a material such as resin, ceramic, or dental amalgam.
In advanced cases where the tooth cannot support a filling, a crown will be placed to protect the weakened tooth.
Here are some options that your dentist may suggest:

Dental filling

dental filling types

When the decay has not yet reached the pulp and the crown destruction is not very extensive, the tooth will be filled with dental material to protect the pulp and restore the shape and function of the tooth.
After cleaning the cavity, the filling will be made directly on the tooth.


inlay and onlay

Inlays and Onlays are ceramic restorations that fit the tooth cavity. It is a good alternative when dental fillings cannot be made due to a too large cavity. Unlike dental fillings, inlays and Onlays are made outside the mouth.


dental filling crown

Your dentist will suggest a crown when the destruction of the tooth is much more important.

If the pulp is affected, your dentist will perform an endodontic treatment to remove all the infected tissues and then he will fill the emptied root canals.
Among the options available to restore the tooth with a root canal treatment:



Endocrowns are ceramic restorations indicated for severely damaged molars with root canal treatment.

Post crown

post crown

Post crowns are also indicated for teeth with root canal treatment. They are composed of 2 parts: a part that will fit the root canal called “post”, and another visible external part called “crown” which is identical to the conventional crown.
You may need a post crown if your tooth has a root canal treatment and the crown is too weak to support a crown or endocrown.

Sometimes, it is impossible to keep the tooth, extraction is necessary. The missing tooth will be replaced by an implant or bridge.


Here are some tips to prevent tooth decay:
  • Brush with fluoride toothpaste at least twice a day.
  • Floss your teeth daily.
  • Rinse your mouth with natural mouthwashes.
  • Visit your dentist regularly.
  • Drink a lot of water.
  • Balance your diet.
  • Avoid snacking and sipping frequently.
  • Eat healthy foods for your teeth that are rich in minerals and water like green vegetables, cheese, apples, tea, fish...
  • Consider fluoride treatments.
  • Learn about antibacterial treatments. If you're especially vulnerable to tooth decay — for example, because of a medical condition — your dentist may recommend special antibacterial mouth rinses or other treatments to help cut down on harmful bacteria in your mouth.