An Insight on Cementoenamel Junction

The tooth is made up of several mineralized layers that protect the pulp tissue and maintain the integrity of the tooth. It is essential to know about each component of the tooth to understand different oral conditions that can affect the teeth and the gums. Everyone is well aware of the enamel and its functions. Another most critical component of the tooth is the cementoenamel junction.

A cementoenamel junction is an anatomical border present on the surface of the tooth. It is commonly known as the neck of the tooth. The overlapping of enamel and cementum forms a cementoenamel junction. The gingival margin usually covers it. However, during active gum recession, cementoenamel may get exposed.


Commonly abbreviated as CEJ, the cementoenamel junction is the source of tooth sensitivity for many people who do not follow proper oral hygiene measures. The cementoenamel junction is a delicate zone which is prone to progressive depletion. Therefore, it is essential to protect this area. Today’s article will highlight the importance of cementoenamel junctions, its formation, and simple ways to protect this unique junction.

What is the cementoenamel junction?

Cementoenamel junction, abbreviated as CEJ, is characterized by a specific line around the perimeter of the tooth. This is the junction where the layer of enamel covering the crown meets cementum that includes the root of the tooth. (1) Most of the cementoenamel intersections are formed by overlapping of enamel and cementum. However, in some cases, the two layers may not overlap and create a gap which is covered by a thin band of exposed dentin.

Frequently, the cementoenamel junction is also referred to as the neck of the tooth. This is because the location of this unique junction is close to the gingival attachment of a healthy tooth. The connective tissue layer of the gingival forms a protective cover over the CEJ. It keeps the less mineralized cemental layer of the root warm and away from bacteria and acids. (2)

What are the different types of the cementoenamel junction?

The formation of the cementoenamel junction, typically, involves three types of mineralized tissues – enamel, dentin, and cementum. Clinically, the cementoenamel intersection is a non-uniform line with regular contour. However, the formation of the cementoenamel junction may vary from one person to another. Following are the different types of the cementoenamel junction –

  • The overlapped junction – in this the cemental layer usually overlaps the enamel for a short distance. Overlapped junctions are seen in 60% of all the teeth. Typically, the degeneration of enamel at the cervical region allows connective tissue cells of cementum to contact the enamel directly. (3)
  • Alternate overlap junction – a variation to the CEJ mentioned above is the overlap junction wherein the enamel overlaps the cementum. This type of junction occurs rarely and is seen in 1.6% of all teeth.
  • End to End junction – as the name suggests, in this case, the cemental and enamel layer meet end to end with each other. The junction formed is called a butt joint. End to end cementoenamel junctions are seen in 30% of all teeth.
  • Gap junction – often, the enamel and cemental layers may not overlap or meet at the junctional point. During this stage, the junction is covered by a thin band of dentin. The absence of contact leads to elimination of cementoenamel junction. Gap junctions are seen in 10% of all teeth.

Often one of these patterns predominates in an individual. However, when traces circumferentially, all these patterns can be observed.

What are the symptoms of cementoenamel exposure?

Usually, the cementoenamel junction is protected by the gingival margin. However, during the gum recession, the CEJ may get exposed to the mouth. This makes the cementum vulnerable to wear and tear from aggressive brushing habits. Moreover, chewing and clenching of teeth may also affect the integrity of exposed cementum.

Removal of the cemental layer from the junction exposed the dentin covering the root of the tooth. Exposure of dentin to the mouth may lead to tooth sensitivity, especially to hot and cold foods. As the CEJ gets exposed to bacteria and acids in the mouth, it increases the risk of root caries and tooth decay. (4)

How is the clinical attachment of gums measured?

During the gum recession, dental professionals often measure the clinical attachment of the gums to determine the degree of CEJ exposure. Usually, the clinical attachment of the gums is measured by running a periodontal probe around the tooth. (5)

A periodontal probe is a unique measuring ruler which is used to assess the gingival health of an individual. The dental professional may place the periodontal probe in the space along the CEJ to determine the clinical attachment of the gingival tissue.

During the assessment, the dentist also makes a note of the areas of gum recession. These areas compared to the previous charting visit, determining the progression of gum disease. Often, the evaluation of attachment fibers between the teeth and bone can predict the presence of periodontal infections, inflammation, or further recession.

How to protect the Cementoenamel junction?

As mentioned above, the cementoenamel junction is protected by the gingival tissue. Therefore, to protect the CEJ, it is essential to maintain the health of our teeth and gums.

  • Follow a proper oral healthcare routine which includes regular tooth brushing and flossing.
  • Always rinse your mouth after every meal
  • An antibacterial mouthwash can add beneficial value to your oral health
  • Regular dental appointments will help to detect early signs of gum disease or tooth decay. Early diagnosis and prompt treatment will help to eliminate the disease progression and exposure of CEJ.

Take away message

CEJ is usually formed by the overlapping of enamel over cementum or vice versa. This overlapping of mineralized tissues creates a distinct line which forms the neck of the tooth. The gingival tissue often covers Cementoenamel junctions. But, they may get exposed to the mouth during the gum recession.

Most of the cases may have overlapped cementoenamel junctions. However, in some rare instances, the two mineralized layers may not overlap or meet, which leaves a gap in between. This gap is covered by a thin layer of dentin covering the root of the tooth. Often in this situation, exposure of CEJ may cause tooth sensitivity.


Good oral health care routine and regular dental appointments are essential to maintain in the health of your teeth and gums. Moreover, it protects the delicate parts of the tooth, such as the cementoenamel junction.


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