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Topic

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Dentine

Dentine is the hard, calcified tissue that forms the bulk of the tooth, lying beneath the enamel in the crown and beneath cementum in the root. It surrounds and protects the pulp chamber and root canal system, providing both structural strength and shock absorption during mastication.

Unlike enamel, dentine is less mineralized, more elastic, and biologically active, containing microscopic dentinal tubules that extend from the pulp outward toward the enamel or cementum. These tubules play a key role in tooth sensitivity and structural resilience.

Synonyms

  • Dentin (American spelling)

  • Dental dentine

Location and Structure

  • Position: Between enamel (externally) and pulp (internally) in the crown; between cementum and pulp in the root

  • Composition:

    • Approximately 70% inorganic (hydroxyapatite)

    • 20% organic matrix (mainly collagen type I)

    • 10% water

  • Dentinal tubules: Microscopic channels radiating from pulp to periphery, increasing in density toward the pulp

  • Types of dentine:

    • Primary dentine (formed during tooth development)

    • Secondary dentine (formed after eruption)

    • Tertiary dentine (reactionary or reparative)

Relations

  • Externally (crown): Enamel

  • Externally (root): Cementum

  • Internally: Dental pulp

  • Peripherally: Dentinoenamel junction (DEJ) and dentinocemental junction (DCJ)

Function

  • Structural support: Forms the main body of the tooth

  • Shock absorption: Protects brittle enamel during mastication

  • Protection of pulp: Acts as a barrier against thermal and mechanical stimuli

  • Sensory role: Dentinal tubules transmit stimuli to the pulp

  • Adaptability: Capable of continued deposition throughout life

Clinical Significance

  • Determines overall tooth strength and resilience

  • Plays a major role in tooth sensitivity

  • Serves as a protective layer for the pulp chamber

  • Critical reference tissue in dental imaging and restorative planning

MRI Appearance

T1-weighted images:

  • Dentine appears as low-to-intermediate signal intensity

  • Signal is lower than fatty bone marrow and higher than enamel

  • Clear contrast between dentine and pulp, with pulp appearing relatively brighter

  • Enamel remains very low signal, allowing dentine to be distinguished as an intermediate layer

T2-weighted images:

  • Dentine shows low-to-intermediate signal, slightly brighter than enamel

  • Pulp appears hyperintense due to its fluid content

  • Dentinal tubule structure is not individually resolved but contributes to uniform intermediate signal

STIR:

  • Dentine appears intermediate-to-dark

  • Strong suppression of fat improves contrast with surrounding alveolar marrow

  • Dentine remains clearly distinguishable from bright pulp and suppressed marrow

CT Appearance (Pre-Contrast Only)

Non-Contrast CT:

  • Dentine appears as a moderately hyperdense structure

  • Density is less than enamel but greater than pulp

  • Forms a thick concentric layer around the pulp cavity

  • Dentinoenamel junction and dentinocemental junction are well visualized

  • High spatial resolution CT clearly differentiates enamel, dentine, pulp, and surrounding bone

Dental X-ray Appearance

  • Dentine appears radiopaque, but less radiopaque than enamel

  • More radiopaque than pulp, which appears radiolucent

X ray image

Dentine