Dentin. Types. Structure. Role

Lying immediately beneath dental enamel and cementum, dentin is the main mass, the formation that occupies most space both coronally and root-wise.

It is an important tissue, immediately adjacent to the dental pulp, so dentin has the ability to adapt to changes caused by oral health disruptors.

Types of dentin

There are 3 different types of dentin, each occurring at different times of life and fulfilling distinct roles:

  • Primary dentin: is present from the very beginning, during tooth formation, and is strongly innervated but not vascularized. It has the ability to transmit information about conditions in the oral cavity to the dental pulp.

  • Secondary dentin: settles with age, as root canals narrow over time. It has a darker color and gives the teeth a yellowish tint in elderly people.

  • Tertiary dentin or reaction dentin: this last type of dentin only forms when there is a factor that aggresses the dental unit. As a response in an attempt to protect the dental pulp, reaction dentin is deposited in the direction from which the stimulus originates. If, however, the speed of deposition of the reaction dentin is slower than the speed of penetration of the infectious process, the defense capacity is exceeded and we will have pulpal complications. Usually, the rate of deposition of tertiary dentin is faster in younger patients.

Dentin structure and properties

It is a less mineralized tissue than tooth enamel, containing 70% hard substance (compared to 90% enamel). On radiological examination, it appears less opaque than enamel, with a greyish shade.

Roles of dentin

  • plays a decisive role in the shade of the tooth: enamel is a translucent tissue that allows the dentin to be seen through its transparency. The darker the shade of dentin, the yellower the tooth will be.

  • it receives sensations transmitted by stimuli: the dentin is crisscrossed by canaliculi that present nerve endings. The metabolism of dentin is influenced by this information received via nerve endings. The stimuli that can be received are thermal, tactile or painful.

  • fight destructive processes: they have the ability to protect the dental pulp. By depositing tertiary dentin, the advance of pathogenic processes is slowed down. Once the pathological process, be it carries or abrasion, has reached the dentin, it will spread much more rapidly due to its reduced hardness.

Pathology treatment that affects dentin

The therapeutic approach is varied depending on the amount of dentin affected and the existence of pulpal complications.

In most cases, the approach to patients requires multidisciplinary collaboration.

Regardless of which service the patient is referred to, the universal goal is the preservation of healthy tissue.

In the case of small losses of dental hard substance, the deficit will be replaced by filling with composites that will accurately mimic the physical properties of the tooth. For moderate and large losses, dental laboratory intervention is required for the production of inlays, onlays, veneer or replacement crowns. Prevention is also in this case the best solution in maintaining the integrity of the teeth.

Often, a crack or a minimal loss of enamel substance hides an extensive caries process at the dentinal level.

This phenomenon is due to weaker dentin mineralization.

The dentist will examine each tooth of the arch and will use additional examinations such as radiology or transillumination to detect the destructive processes affecting the dentin and their relationship with the pulp chamber.

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