Cementoenamel junction

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Cementoenamel junction
Labeledmolar.jpg
Labeled molar
The Periodontium.jpg
The CEJ is the more or less horizontal demarcation line that distinguishes the crown (A) of the tooth from root (B) of the tooth.
Identifiers
MeSH D019237
Anatomical terminology

Cementoenamel junction (CEJ) is defined as the area of the union of cementum and enamel at the cervical region of the tooth. It is a slightly visible anatomical border identified on a tooth. It is the location where the enamel, which covers the anatomical crown of a tooth, and the cementum, which covers the anatomical root of a tooth, meet. Informally it is known as the neck of the tooth. [1] The border created by these two dental tissues has much significance as it is usually the location where the gingiva attaches to a healthy tooth by fibers called the gingival fibers. [2]

Contents

Active recession of the gingiva reveals the cementoenamel junction in the mouth and is usually a sign of an unhealthy condition. The loss of attachment is considered a more reliable indicator of periodontal disease. The CEJ is the site of major tooth resorption. A significant proportion of tooth loss is caused by tooth resorption, which occurs in 5 to 10 percent of the population. The clinical location of CEJ which is a static landmark, serves as a crucial anatomical site for the measurement of probing pocket depth (PPD) and clinical attachment level (CAL). The CEJ varies between subjects, but also between teeth from the same person. [1]

There exists a normal variation in the relationship of the cementum and the enamel at the cementoenamel junction. In about 60–65% of teeth, the cementum overlaps the enamel at the CEJ, while in about 30% of teeth, the cementum and enamel abut each other with no overlap. In only 5–10% of teeth, there is a space between the enamel and the cementum at which the underlying dentin is exposed. [3]

Formation

In the tooth bud, regions where enamel formation is completed, the enamel organ gives rise to Hertwig's epithelial root sheath, composed of two epithelial layers derived from the external and internal epithelia. The sheath is irregularly fragmented in time and space as it promotes cementum deposition on the newly formed dentin. After this fragmentation, Hertwig's epithelial root sheath also participates in cementogenesis and formation of the periodontal ligament, giving rise to the epithelial rests of Malassez. This irregular fragmentation of Hertwig's epithelial root sheath yields an equally irregular limit of cervical enamel and an irregular onset of formation and deposition of cementum. Consequently, the relationship between cementum and enamel at the CEJ presents an irregular contour, as observed during scanning electron microscope (SEM) analysis of the primary teeth.

Fragmentation of Hertwig's epithelial root sheath and exposure of dentin covered by a thin layer of intermediate cementum are fundamental for the onset of cementogenesis. If Hertwig's epithelial root sheath is not fragmented, there will be enamel deposition and it will be transformed into reduced epithelium, thus preventing cementum deposition on its surface. [4]

Types

Curvature

Comparison of the cementoenamel junction on the mesial surfaces of the maxillary central, first bicuspid, and first molar Curvature of CEJ.jpg
Comparison of the cementoenamel junction on the mesial surfaces of the maxillary central, first bicuspid, and first molar

The shape and location of the cementoenamel junction (CEJ) on each tooth surface should be considered. CEJs differ from tooth to tooth in terms of their anatomy. The curvature of the CEJ is greatest on anterior teeth due to the narrow profile of these teeth. [6] On the anteriors, the distal aspect's curvature is usually one mm lower than the mesial aspect. Posterior teeth have flatter CEJ curvatures on the inter-proximal surfaces in comparison to the anteriors. [7]

Teeth resorption

Root resorption often starts at cementoenamel junction (CEJ) in teeth. Types of tooth resorption include internal resorption and external resorption. [8]

Internal

There are two types of internal resorption - root canal (internal) replacement resorption and internal inflammatory resorption.

Types of Resorption Types of Resorption.png
Types of Resorption

External

External resorption can be classified into four categories by its clinical and histologic manifestations: external surface resorption, external inflammatory root resorption, replacement resorption, and ankylosis. External inflammatory root resorption can be further categorized into cervical resorption with or without a vital pulp (invasive cervical root resorption) and external apical root resorption. [8]

Related Research Articles

<span class="mw-page-title-main">Human tooth</span> Calcified whitish structure in humans mouths used to break down food

Human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. As such, they are considered part of the human digestive system. Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla or the mandible and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.

<span class="mw-page-title-main">Cementum</span> Specialized calcified substance covering the root of a tooth

Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.

<span class="mw-page-title-main">Abfraction</span> Loss of tooth structure not caused by tooth decay

Abfraction is a theoretical concept explaining a loss of tooth structure not caused by tooth decay. It is suggested that these lesions are caused by forces placed on the teeth during biting, eating, chewing and grinding; the enamel, especially at the cementoenamel junction (CEJ), undergoes large amounts of stress, causing micro fractures and tooth tissue loss. Abfraction appears to be a modern condition, with examples of non-carious cervical lesions in the archaeological record typically caused by other factors.

<span class="mw-page-title-main">Enamel organ</span> Aggregate of cells involved in tooth development

The enamel organ, also known as the dental organ, is a cellular aggregation seen in a developing tooth and it lies above the dental papilla. The enamel organ which is differentiated from the primitive oral epithelium lining the stomodeum. The enamel organ is responsible for the formation of enamel, initiation of dentine formation, establishment of the shape of a tooth's crown, and establishment of the dentoenamel junction.

<span class="mw-page-title-main">Human tooth development</span> Process by which teeth form

Tooth development or odontogenesis is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. For human teeth to have a healthy oral environment, all parts of the tooth must develop during appropriate stages of fetal development. Primary (baby) teeth start to form between the sixth and eighth week of prenatal development, and permanent teeth begin to form in the twentieth week. If teeth do not start to develop at or near these times, they will not develop at all, resulting in hypodontia or anodontia.

<span class="mw-page-title-main">Dental papilla</span>

In embryology and prenatal development, the dental papilla is a condensation of ectomesenchymal cells called odontoblasts, seen in histologic sections of a developing tooth. It lies below a cellular aggregation known as the enamel organ. The dental papilla appears after 8–10 weeks intra uteral life. The dental papilla gives rise to the dentin and pulp of a tooth.

A cementoblast is a biological cell that forms from the follicular cells around the root of a tooth, and whose biological function is cementogenesis, which is the formation of cementum. The mechanism of differentiation of the cementoblasts is controversial but circumstantial evidence suggests that an epithelium or epithelial component may cause dental sac cells to differentiate into cementoblasts, characterised by an increase in length. Other theories involve Hertwig epithelial root sheath (HERS) being involved.

<span class="mw-page-title-main">Epithelial root sheath</span>

The Hertwig epithelial root sheath (HERS) or epithelial root sheath is a proliferation of epithelial cells located at the cervical loop of the enamel organ in a developing tooth. Hertwig epithelial root sheath initiates the formation of dentin in the root of a tooth by causing the differentiation of odontoblasts from the dental papilla. The root sheath eventually disintegrates with the periodontal ligament, but residual pieces that do not completely disappear are seen as epithelial cell rests of Malassez (ERM). These rests can become cystic, presenting future periodontal infections.

Cementogenesis is the formation of cementum, one of the three mineralized substances of a tooth. Cementum covers the roots of teeth and serves to anchor gingival and periodontal fibers of the periodontal ligament by the fibers to the alveolar bone.

Dens invaginatus (DI), also known as tooth within a tooth, is a rare dental malformation where there is an infolding of enamel into dentine. The prevalence of condition is 0.3 - 10%, affecting more males than females. The condition is presented in two forms, coronal and radicular, with the coronal form being more common.

<span class="mw-page-title-main">Enamel pearl</span> Medical condition

Enamel pearls are developmental variations of teeth that present as beads or nodules of enamel in places where they are not normally observed.

<span class="mw-page-title-main">Taurodontism</span> Molar condition in which the root is relatively short

Taurodontism is defined as the enlargement of pulp chambers with the furcation area being displaced toward the apex of the root of a tooth. It cannot be diagnosed clinically and requires radiographic visualization since the crown of a taurodontic tooth appears normal and its distinguishing features are present below the alveolar margin. Taurodontism can present in deciduous or permanent dentition, unilaterally or bilaterally, but is most common in the permanent molar teeth of humans. The underlying mechanism of taurodontism is the failure or late invagination of Hertwig's epithelial root sheath, which leads an apical shift of the root furcation.

Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. Tooth formation begins before birth, and the teeth's eventual morphology is dictated during this time. Dental anatomy is also a taxonomical science: it is concerned with the naming of teeth and the structures of which they are made, this information serving a practical purpose in dental treatment.

<span class="mw-page-title-main">Crown-to-root ratio</span>

Crown-to-root-ratio is the ratio of the length of the part of a tooth that appears above the alveolar bone versus what lies below it. It is an important consideration in the diagnosis, treatment planning and restoration of teeth, one that hopefully guides the plan of treatment to the proper end result.

The junctional epithelium (JE) is that epithelium which lies at, and in health also defines, the base of the gingival sulcus. The probing depth of the gingival sulcus is measured by a calibrated periodontal probe. In a healthy-case scenario, the probe is gently inserted, slides by the sulcular epithelium (SE), and is stopped by the epithelial attachment (EA). However, the probing depth of the gingival sulcus may be considerably different from the true histological gingival sulcus depth.

Dental pertains to the teeth, including dentistry. Topics related to the dentistry, the human mouth and teeth include:

<span class="mw-page-title-main">Tooth resorption</span> Medical condition

Resorption of the root of the tooth, or root resorption, is the progressive loss of dentin and cementum by the action of odontoclasts. Root resorption is a normal physiological process that occurs in the exfoliation of the primary dentition. However, pathological root resorption occurs in the permanent or secondary dentition and sometimes in the primary dentition.

In dentistry, enamel matrix derivative (EMD) is an extract of porcine fetal tooth material used to biomimetically stimulate the soft and hard tissues surrounding teeth to regrow following tissue destruction.

Height of curvature in the tooth can be defined as the line encircling a tooth at its greatest bulge to a selected path of insertion. The height of curvature is the same as the height of contour.

Hard tissue, refers to "normal" calcified tissue, is the tissue which is mineralized and has a firm intercellular matrix. The hard tissues of humans are bone, tooth enamel, dentin, and cementum. The term is in contrast to soft tissue.

References

  1. 1 2 Vandana KL, Haneet RK (September 2014). "Cementoenamel junction: An insight". Journal of Indian Society of Periodontology. 18 (5): 549–554. doi: 10.4103/0972-124X.142437 . PMC   4239741 . PMID   25425813.
  2. ↑ Clemente CD (1987). Anatomy, a regional atlas of the human body. Internet Archive. Baltimore : Urban & Schwarzenberg. ISBN   978-0-8067-0323-7.
  3. ↑ Carranza FA, Bernard GW (2002). "The Tooth-Supporting Structures". In Newman MG, Takei HH, Carranza FA (eds.). Carranza's Clinical Periodontology (9th ed.). Philadelphia: W. B. Saunders. p. 43. ISBN   978-0-7216-8331-7.
  4. ↑ Scheid RC (2012). Woelfel's Dental Anatomy (7th ed.). Lippincott Williams & Wilkins. ISBN   978-1-60831-746-2.
  5. ↑ Metwally S, Stachewicz U (October 2020). "Teeth resorption at cement - enamel junction (CEJ) - Microscopy analysis". Micron. 137: 102913. doi: 10.1016/j.micron.2020.102913 . PMID   32590194. S2CID   220120744.
  6. ↑ "Remembering Your Roots". Dimensions of Dental Hygiene | Magazine. 2021-09-22. Retrieved 2023-08-07.
  7. ↑ Nelson SJ, Ash MM (2010). Wheeler's dental anatomy, physiology, and occlusion (9th ed.). Philadelphia, Pa., London: Saunders. ISBN   978-1-4160-6209-7.
  8. 1 2 Ne RF, Witherspoon DE, Gutmann JL (January 1999). "Tooth resorption". Quintessence International. 30 (1): 9–25. PMID   10323155.
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