Dental Anatomy: Enamel and Dentin Overview

Dental enamel is primarily composed of inorganic material (96%) with organic material and water making up the remaining 4%.

The main inorganic component of dental enamel is hydroxyl apatite.

The basic structural units of enamel, arranged in a rod-like shape.

Generally perpendicular to the dentin surface, becoming straight near the enamel's outer surface.

A thin organic layer covering the enamel surface of newly erupted teeth.

Alternating dark and light bands visible in the middle and cervical thirds of enamel, absent in occlusal/incisal portions.

Dark transverse lines of enamel indicating growth stages—includes cross-striations and striae of Retzius.

A delicate organic membrane covering newly erupted teeth (primary enamel cuticle).

Organized structures in dental enamel, arranged in a specific orientation.

Material that fills the space between enamel rods.

A line in enamel showing the boundary between enamel formed before birth and after.

The border between enamel and dentin in teeth.

Thin, sheet-like structures within enamel, extending from the surface.

Ribbon-like structures in enamel, extending from the amelodentinal junction.

Areas where enamel rods are twisted together for extra strength.

Ranges from yellowish-white to grayish-white.

Variable, thickest on cusps and incisal edges, thins at the neck.

Hardest calcified tissue due to mineral content and crystal structure.

Decreases from outer surface to the dentin boundary, permanents are denser.

Enamel has a degree of permeability, ability to let things pass through.

A type of cementum that lacks cells (cementocytes), located on the coronal and middle thirds of the root.

Dental dentin is composed of dentinal tubules, odontoblastic processes, and incremental lines.

Closely packed, hollow tubes running through dentin from pulp to surface.

A type of cementum that contains cells (cementocytes), found mostly at the root's apical third and interradicular areas. Often termed Secondary cementum

Cytoplasmic extensions of odontoblasts, found within dentinal tubules.

Cells found in cellular cementum, with the cell body in lacunae. Have a granular cytoplasm and a faint nucleus.

A layer that sometimes separates cementum from dentin. It's neither dentin nor cementum in its structure.

Fine lines in dentin marking periods of activity and rest during formation.

Cementum attaches periodontal ligament fibers to the alveolar bone.

Areas of hypocalcification in dentin, highlighting calcification disturbances.

A line in deciduous teeth and some permanent molars marking the birth-related change.

Cementum deposition can offset enamel loss from wear, mostly towards apical parts of roots.

Dentinal tubules follow S-shaped paths in crowns, straighter courses in roots.

A major tissue for repairing root surface damage from fractures or resorption.

The boundary between dentin and enamel; Scalloped in permanent, smooth in deciduous.

Excessive cementum growth.

The boundary between dentin and cementum; usually smooth in permanent, scalloped in deciduous.

The ability of cementum to allow substances through

Nerve fibers branching to areas near odontoblasts.

Endings of odontoblastic processes within enamel, found in the occlusal/incisal crown third, not in Hunter-Schreger bands.

Calcified dental tissue covering tooth roots.

Starts at the cemento-enamel junction, goes to the apex.

Part of the dentin formation process. They extend between the enamel epithelium.

Space between the dentinal tubule wall and odontoblastic processes, containing tissue fluid and collagen fibers.

Light yellow.

Thicker near the apex (150-200 microns), thinner (20-50 microns) at root neck.

Highly calcified dentin surrounding odontoblastic processes, forming dentinal tubule walls.

Less hard than enamel but harder than dentin.

Main body of dentin, located between dentinal tubules.

More elastic than enamel and dentin.

Areas of unmineralized or hypomineralized dentin in mature dentin.

Always near the cementum, a constant root dentin feature with a granular appearance from interglobular dentin.

45-50% inorganic, 50-55% organic materials.

Lines showing cementum growth stages.

Main bulk of the tooth, covered by enamel in the crown and cementum in the root.

Usually smooth in permanent teeth, scalloped in deciduous teeth.

Yellowish

Ranges from 3-10 mm or more.

Variable; meets enamel in sharp line in 30% of teeth; not uniform throughout teeth.

Less hard than enamel.

Network of nerves in the dentin close to the cementum.

More elastic than enamel.

Dental dentin contains a higher percentage of organic material than enamel.