Tooth Development Intro DS1101

A comprehensive set of vocabulary flashcards covering the stages, cell layers, transitory structures, and clinical abnormalities related to tooth development (odontogenesis) as presented in the DS1101 lecture.

Tooth germ

An anatomically distinct unit that develops into a tooth and its supporting structures, consisting of the enamel organ, dental papilla, and dental follicle.

Ecto-mesenchyme

A type of connective tissue derived from neural crest cells (originally ectoderm) that gives rise to the dental papilla and dental follicle.

Enamel organ

The epithelial component of the tooth germ, derived from ectoderm, which is responsible for the formation of enamel.

Dental papilla

The part of the tooth germ derived from ecto-mesenchyme that produces dentine and pulp.

Dental follicle

The part of the tooth germ derived from ecto-mesenchyme that gives rise to the cementum, periodontal ligament, and alveolar bone.

Primary epithelial band

A structure formed by the proliferation of oral epithelium that appears by the $6^{th}$ week of intra uterine life (IUL).

Dental lamina

A process of the primary epithelial band, appearing by the $7^{th}$ week of IUL, whose formation signals the beginning of tooth development and eventually gives rise to $52$ buds.

Vestibular lamina

One of the two processes formed by the division of the primary epithelial band by the $7^{th}$ week of IUL.

Bud stage

The initial stage of definitive tooth development characterized by localized proliferation of epithelial cells of the dental lamina, forming a bud-shaped enamel organ.

Cap stage

A stage occurring by the $11^{th}$ week of IUL where the deeper surface of the enamel organ invaginates to form a cap shape.

Stellate reticulum

Star-shaped cells in the center of the enamel organ, fully developed at the bell stage, whose inter-cellular spaces are filled with fluid for protection.

Stratum intermedium

A layer of $2$ to $3$ flattened cells lying over the IEE, containing alkaline phosphatase and involved in protein synthesis and transport to ameloblasts.

Inner enamel epithelium (IEE)

Columnar cells at the bell stage, rich in RNA, that eventually differentiate into pre-ameloblasts and then ameloblasts.

Outer enamel epithelium (OEE)

Cuboidal cells separated from surrounding mesenchyme by a basement membrane, involved in maintaining the shape of the enamel organ and substance exchange.

Bell stage

Occurring by the $14^{th}$ week of IUL, this 'differentiation stage' defines the future crown shape and is characterized by the differentiation of IEE cells into pre-ameloblasts.

Epithelial cell rests (pearls) of Serres

Remnants of the dental lamina that may remain in the adult mucosa after the dental lamina breaks down and degenerates.

Reciprocal induction

The process in the late bell stage (starting about the $18^{th}$ week of IUL) where IEE cells and dental papilla cells influence each other to form dentin and enamel.

Ameloblasts

Future enamel-forming cells that differentiate from the inner enamel epithelium after being induced by the first formed dentine.

Odontoblasts

Dentine-forming cells that differentiate from dental papilla cells after induction by pre-ameloblasts.

Enamel knot

A transitory signaling center made of a localized mass of cells in the center of the IEE that bulges into the dental papilla and disappears in the bell stage.

Enamel cord

A transitory strand of cells extending from the stratum intermedium to the stellate reticulum; it is called an enamel septum if it completely divides the stellate reticulum.

Enamel niche

A transitory structure seen when the tooth germ appears to have a double attachment to the dental lamina, enclosing connective tissue within strands.

Cervical loop

The location where the inner enamel epithelium and outer enamel epithelium meet and proliferate to initiate root formation.

Hertwig’s epithelial root sheath (HERS)

A structure created by cell proliferation at the cervical loop that maps out the shape of the root and induces dentine formation in the root.

Epithelial diaphragm

The inward-bent portion of the epithelial root sheath toward the dental papilla that guides the root's base development.

Cell rests of Malassez

Remnants of Hertwig’s epithelial root sheath (HERS) that become trapped in the periodontal ligament and may lead to the development of cysts.

Cementoblasts

Cells differentiated from the dental follicle that produce cementum after the onset of dentinogenesis and the disintegration of HERS.

Hypodontia

A clinical condition referring to the absence of fewer than $6$ teeth, not including third molars.

Oligodontia

A clinical condition referring to the absence of $6$ or more teeth, not including third molars.

Anodontia

The complete clinical absence of all teeth.

Gemination

A developmental disturbance characterized by the partial division of a single tooth germ.

Microdontia

A clinical condition characterized by teeth that are smaller than the normal size.

Macrodontia

A clinical condition characterized by teeth that are larger than the normal size.