DH220 Ch. 6

The process of tooth development

odontogenesis

When does development of primary teeth begin

During the 6th to 7th prenatal week

What are the stages of tooth development

Initiation, bud, cap, bell, apposition and maturation

What happens during the initiation stage

The dental lamina begins to form, induction occurs

What happens during the bud stage

The dental lamina grows into the underlying ectomesenchyme to form tooth buds

What happens during the cap stage

The tooth bud develops into a cap-shaped enamel organ

What happens during the bell stage

The tooth germ develops its final shape and cells begin differentiating

What happens during the apposition stage

Hard tissue matrix is deposited

What happens during the maturation stage

The hard tissues mineralize and become fully developed

One group of cells signals another group of cells to develop in a specific way

induction

An increase in the number of cells through cell division

proliferation

The process in which cells become specialized

differentiation

The process of forming the shape and structure of an organ

morphogenesis

The final development and mineralization of tissues

maturation

The primitive mouth

stomodeum

The tissue that lines the developing oral cavity

oral epithelium

Connective tissue derived from neural crest cells

ectomesenchyme

A thin layer separating the oral epithelium from the underlying ectomesenchyme

basement membrane

A band of oral epithelium that grows into the underlying ectomesenchyme and initiates tooth development

dental lamina

What does the dental lamina give rise to

developing tooth buds

The complete absence of teeth

anodontia

The congenital absence of one or more teeth

partial anodontia

Extra teeth that develop in addition to the normal number

supernumerary teeth

A supernumerary tooth located between the maxillary central incisors

mesiodens

A supernumerary tooth located behind a third molar

distomolar

A developmental condition that can affect the formation of teeth and other ectodermal structures

ectodermal dysplasia

How many tooth buds form in each arch

Ten

Teeth that are larger than normal

macrodontia

Teeth that are smaller than normal

microdontia

the Enamel organ, dental papilla, and dental sac are all parts of what?

the tooth germ

What does the enamel organ develop into

Enamel

What does the dental papilla develop into

Dentin and pulp

What does the dental sac develop into

Cementum, PDL, and alveolar process

A signaling center that helps control cusp development and shape

enamel knot

The dental lamina that produces the permanent teeth that replace primary teeth

successional dental lamina

Permanent teeth that replace primary teeth

succedaneous teeth

Which permanent teeth are succedaneous

Incisors, canines, and premolars

Permanent teeth that do not replace primary teeth

nonsuccedaneous teeth

Which permanent teeth are nonsuccedaneous

molars

An invagination of the developing tooth that creates a tooth within a tooth appearance

dens in dente

An attempt by one developing tooth germ to divide into two teeth

gemination

The joining of two developing tooth germs to form one enlarged tooth

fusion

the outer enamel epithelium, stellate reticulum, stratum intermedium, and inner enamel epithelium are all layers of what?

the enamel organ

What does OEE stand for

Outer enamel epithelium

what forms the outer protective layer of the enamel organ

outer enamel epithelium

The star-shaped cell network within the enamel organ

stellate reticulum

Provides support and maintains space for developing enamel

stellate reticulum

The cell layer between the stellate reticulum and inner enamel epithelium

stratum intermedium

Supports enamel formation and ameloblast activity

stratum intermedium

What does IEE stand for

Inner enamel epithelium

What do inner enamel epithelial cells become

Ameloblasts

What do ameloblasts produce

Enamel

What do the outer cells of the dental papilla become

Odontoblasts

What do the central cells of the dental papilla become

Dental pulp

The formation of dentin

dentinogenesis

The formation of enamel

amelogenesis

Which tissue forms first during tooth development

Dentin

What cells form dentin

Odontoblasts

What cells form enamel

Ameloblasts

Developing inner enamel epithelial cells that will become ameloblasts

pre-ameloblasts

What signals dental papilla cells to become odontoblasts

The pre-ameloblasts

What do odontoblasts secrete

Predentin

The unmineralized organic matrix that forms before dentin mineralizes

predentin

What happens after predentin is secreted

Predentin begins to mineralize and become dentin

What happens to the basement membrane during dentin and enamel formation

It breaks down

What happens to pre-ameloblasts after odontoblast differentiation

They become mature ameloblasts

When does enamel secretion begin

After dentin formation has started

The boundary where dentin and enamel meet

dentinoenamel junction

What does DEJ stand for

Dentinoenamel junction

A projection of an ameloblast involved in enamel matrix secretion

Tomes process

Where do odontoblasts remain after dentin formation

Along the outer edge of the dental pulp

Extensions of odontoblasts that extend into dentinal tubules

odontoblastic processes

Where are odontoblastic processes located

Inside dentinal tubules

What happens to ameloblasts after tooth eruption

They are lost

A developmental abnormality affecting enamel formation

enamel dysplasia

A defect involving reduced enamel quantity

enamel hypoplasia

What does enamel hypoplasia look like

Pits grooves or areas of missing enamel

A defect involving poor enamel mineralization

enamel hypocalcification

Does enamel hypocalcification affect enamel quantity or quality

Quality

What can enamel hypocalcification look like

Opaque yellow or brown areas

An enamel defect caused by excessive fluoride exposure during tooth development

dental fluorosis

An inherited condition that affects enamel formation

amelogenesis imperfecta

A permanent tooth with a localized enamel defect often caused by infection or trauma involving its primary predecessor

Turner tooth

A developmental abnormality affecting dentin formation

dentin dysplasia

An inherited disorder affecting dentin formation

dentinogenesis imperfecta

What color can teeth with dentinogenesis imperfecta appear

Blue-gray or brown with an opalescent appearance

The joining of two teeth by cementum

concrescence

A small deposit of enamel located on a tooth root

enamel pearl

An abnormal bend or distortion in the root or crown of a tooth

dilaceration

Extra roots that develop on a tooth

accessory roots

What structure begins root development

The cervical loop

What does HERS stand for

Hertwig epithelial root sheath

An epithelial structure that guides root shape and development, induce root dentin formation

Hertwig epithelial root sheath

What happens to HERS after it performs its function

It breaks down

Remnants of HERS that remain in the periodontal ligament

epithelial rests of Malassez

What cells form cementum

Cementoblasts

The unmineralized organic matrix of cementum

cementoid

What happens to cementoid

It mineralizes to become cementum

Cementoblasts that become trapped within the cementum they produce

cementocytes

The boundary where dentin and cementum meet

dentinocemental junction