TERMINOLOGY USED TO DESCRIBE THE PARTS

OF A TOOTH

FOUR TISSUES OF A TOOTH

Enamel

Dentin

Cementum

Pulp

Enamel It is the white, protective external surface layer of the anatomic crown.

highly calcified or mineralized,

hardest substance in the body.

Its mineral content is 95% calcium hydroxy- apatite (which is calcified).

The remaining substances include 5% water and enamel matrix.

It develops from the enamel organ (ectoderm) and is a product of specialized epithelial cells called ameloblasts

Cementum It is the dull yellow external layer of the tooth root.

The cementum is very thin, especially next to the cervical line (only 50–100 μm thick)

It is composed of 65% calcium hydroxyapatite (mineralized and calcified),

35% organic matter (collagen fibers), and 12% water.

It develops from the dental sac (mesoderm), and is produced by cells called cementoblasts

Cementoenamel Junction (CEJ)

It separates the enamel of the crown from the cementum of the anatomic root.

Also known as the cervical line, denoting that it surrounds the neck or cervix of the tooth.

DentinIt is the hard yellowish tissue underlying the enamel and cementum

Makes up the major bulk of the inner portion of each tooth crown and root.

Mature dentin is composed of about 70% calcium hydroxyapatite, 18% organic matter (collagen fibers), and 12% water,

Making it harder than cementum but softer and less brittle than enamel.

It develops from the embryonic dental papilla (mesoderm).

The odontoblasts cells that form dentin, are located at the junction between pulp and dentin.

Dentinoenamel Junction (DEJ)Cementoenamel Junction (CEJ)

DEJ = is the inner surface of the enamel cap where enamel joins dentin.

This junction can be best seen on a radio- graph.

CEJ = is the inner surface of cementum where cementum joins dentin.

Cementum is so thin that it is difficult to identify this junction on a radiograph.

Pulpis the soft (not calcified or mineralized) tissue in

the cavity or space in the center of the crown and root called the pulp cavity.

The pulp cavity has a coronal portion (pulp chamber) and a root portion (pulp canal or root canal).

Pulp It develops from the dental papilla (mesoderm).

Pulp is soft connective tissue containing a rich supply of blood vessels and nerves.

Functions of the dental pulp are as follows: FormativeSensory Nutritive Defensive

ANATOMIC VERSUS CLINICAL CROWN AND ROOT

The anatomic crown is that part of the tooth (in the mouth or handheld) normally covered by an enamel layer

Anatomic root is the part of a tooth covered by cementum.

The clinical crown refers specifically to the amount of tooth visible in the oral cavity,

The clinical root refers to the amount of tooth that is not visible since it is covered with gingiva (gum tissue).

End.