Chapter 19: Dental Lamina and Enamal Organ

Dental lamina

Thickened band of oral epithelium that follows the curve of each developing arch

When does the dental lamina begin forming

6th embryonic week

The 20 thickened sites of dental lamina will form

The enamal of teeth

Bud stage

First stage in development of enamal organ, initial budding of dental lamina in 20 areas

What forms the tooth enamal

Enamal organ

During the bud stage only ________ of the tissues occurs, no _________ change to the cells

Proliferation, structural

All teeth and their associated tissues develop from both the ________ and _______ tissue

Ectoderm, mesoderm (Ectomesenchyme)

In areas where teeth will not develop the dental lamina

Merely thickens

Macrodontia

Abnormally large teeth

- fusion

- gemenition

Microdontia

Abnormally small teeth

- peg lateral (maxillary lateral incisor most common tooth)

- peg molars

When does microdontia occur

During bud stage

The localized form of microdontia is

Hereditary

Microdontia means ________ dysfunction is complete

Endocrine

What teeth does microdontia commonly involve

Permanent maxillary lateral incisors and third molars

When does macrodontia occur

During bud stage of development

Macrodontia usually results in ________ dentition

Partial

Macrodontia can be a dysfunction of the _________ gland

Pituitary

What are the 3 components of the cap stage

Outer enamal epithelium, inner enamal epithelium, stellate reticulum

What do the cap stage components do

Get ready to produce enamal, each layer is responsible for building enamal

Outer enamal epithelium

Outermost part of structure, direct continuation of basal layer of oral epithelium (red)

What cells make up the OEE

Low columnar and cuboidal cells

Inner enamal epithelium

Outline the concavity in the deepest part, continuous with OEE cells (light green)

What does the IEE originate from

Basal layer of oral epithelium

Stellate reticlum

Between IEE and OEE, ectodermal cells

What layer of oral epithelium does the stellate reticulum originate from

Superficial layers

Is there an equal or unequal growth of the tooth bud during the cap stage

Unequal, one side is thicker than the other

Cap stage

Formation of a cap shape or enamal organ attached to the dental lamina

What is the pre-dominant physiological process during the cap stage

Morphogenesis

Morphogenesis

How it's changing it's shape

What part of the enamal organ determines the tooth's future crown form

Inner most margin of the cap shape

What does the dental papilla give rise to

Dentin and pulp

Dental sac

Condensed mass of ectomesenchyme surrounding the enamal organ

What will the dental sac give rise to

cementum, periodotal ligament, and alveolar bone

Gemination

Tooth germ tries to divide but results in 1 large tooth

When gemintaion occurs is there more or less teeth in the mounth

Same amount of teeth with less space

What do the roots of fused teeth look like

2 roots fused together

What do the roots of germintation look like

2 crowns sharing 1 root

Dens in dente

Tooth within a tooth

When a tooth grows inside another tooth the ________ ________ invaginates into the ________ ________

Enamal organ, dental papilla

Dens in dente is H_______

Hereditary

Which tooth does dens in dente commonly affect? this tooth may have a deep _______ pit and need _________ therapy depending on the _______

Permanent maxillary lateral incisor. Lingual, endodontic, root

Tubercle

Extra cusp

What can cause a tubercle

Trauma, pressure, and metabolic disease

A tubercle is common on permanent _______ or ________ of ______ teeth

Molars, cingulum, anterior

During what stage of the cap stage does an enamal pearl occur

Apposition and maturation stage

An enamal pearl is the

Displacement of ameloblasts on the root surface (cementum)

All the developmental disturbances occur during which stage of the enamal organ

Cap stage

Bell stage of enamal organ

3rd stage when a fourth layer of epithelium appears, stratum intermedium

The bell stage includes several layers of flattened _______ cells

Squamous

Where is the stratum intermedium

Between IEE and stellate reticulum

What determines the future outline of tooth crown

How cell layers expand during the bell stage

During the bell stage cells change to lead to enamal production, especially which cells

IEE cells

Function of the 4 layers of enamal organ

- OEE : Protective layer later playing a role in gingiva attachment to teeth

- IEE cells: Elongate and change internally to become ameloblasts

- Stellate reticulum: Cushioned protection for IEE cells, nourishes stratum intermedium, and allows vascular fluid to move between cells

- Stratum intermedium: Help provide nourishment to IEE cells and produce protein

Successional lamina

Extension of dental lamina to lingual side of each tooth, go through enamal organ stages to form permanent incisors, canines, and premolars

Permanent molars are

Nonsuccessional

Laminar attachment breaks down as developing teeth reach ______ stage and now primary tooth lamina is _______ lamina

Bell, lateral

Vestibular lamina

Thickening of oral epithelium in facial or buccal direction from dental lamina

The vestibular lamina ______ in the thickened area and eventually forms a ______ which becomes the ________ or _________ fold in future vestibule

Splits, groove, mucobuccal, muccolabial

The dental papillar arises from the _______ and is first seen in the late _____ stage but becomes more pronounced during the ________ stage

Mesoderm, Bud, bell

What is the dental sac aka

Dental follicle

What does the dental sac arise from

Mesoderm