Odontogenesis Flashcards by sophie rosen

Tooth (4)

 Enamel
 Dentin
 Cementum
 Pulp

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Periodontium (4)

 Gingiva
 Periodontal Ligament
 Cementum
 Alveolar Bone Proper

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stages of tooth development (6)

 Initiation 
 Bud Stage 
 Cap Stage 
 Bell Stage 
 Apposition 
 Maturation

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Initiation

Cellular Induction

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Bud Stage

Cellular Proliferation

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Cap Stage

Proliferation, Differentiation

and Morphogenesis

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Bell Stage

Proliferation, Differentiation

and Morphogenesis

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Apposition

Induction and Proliferation

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Maturation

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Epithelium (ectoderm) plays an “instructional” role
during the — — stage of tooth formation.
At this early stage, the fate of the neural crest cells
(mesenchyme) has yet to be fully determined.
Epithelium specifies the “dental nature”of
the —, and the mesenchyme, in turn,
specifies the (2)

pre-tooth bud
mesenchyme
tooth type (incisor vs. molar) and nature of the product produced by the epithelium (i.e., enamel matrix).

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Tooth Development (Induction Stage – 6th to 7th weeks) includes (3)

► Oral Ectoderm
► Neural Crest Cells
► Dental Lamina

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Ectoderm invaginates into
the mesenchyme, and is now
called the

dental lamina

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The lamina is separated
from the surrounding
mesenchyme by a

basement membrane

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Proliferating oral ectoderm making the transition into

dental lamina

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OEE
cell type
function

cuboidal

protective barrier

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IEE
cell type
function

cuboidal cells

differentiate into ameloblasts

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stellate reticulum
cell type
function

star shaped cells forming network inside enamel organ

supportive function in enamel production

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stratum intermedium
cell type
function

compressed layer of flat cuboidal cells

supportive function in enamel production

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dental sac
cell type
function

collagen fibers around enamel organ

differentiated into cementum, PDL, and bone

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dental papilla
cell type
function

cells nearest IEE have basement membrane separation

outer cells differentiate into odontoblasts, whereas inner cells differentiate into pulp tissue

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Cervical Loop

Junction of the outer

& inner enamel epithelia

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Cervical Loop is the site of

cemento-enamel
junction (CEJ) in the adult
tooth (a.k.a., cervix)

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Hertwig’s Epithelial Root Sheath

Fusion and apical
extension of the
outer and inner
enamel epithelia

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Hertwig’s Epithelial Root Sheath determines the

outline of
the root dentin and the
number of roots a tooth
will have.  It is removed
before the cementum is
laid down

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Enamel formation stops at the

termination of the enamel organ

Dentin formation continues, and pushes the tooth

occlusally

The epithelial diaphragm is the

modification of Hertwig’s Sheath creating “septa” that divide the pupal tissue and create mutiple roots.

Root length is not complete until

1 to 4 years after the tooth has emerged into the oral cavity. The pulp chamber narrows, and the apical opening constricts.

first formed dentin

Mantle Dentin

Mantle Dentin thickness

thin, 30-50 um

Mantle Dentin contains both

type 1 and 3 collagen

Mantle Dentin collagen fibers are oriented

perpendicular to the DEJ

Actively secreting | ameloblasts are

tall | columnar cells

Inactive (a.k.a. reduced) | ameloblasts are

short columnar or elongated cuboidal cells

``` At the final stage of mineralization, the reduced ameloblasts with the remaining cells of the outer enamel epithelium, stellate reticulum, and stratum intermedium form a membrane on the surface of the enamel. This is termed the ```

primary cuticle (a.k.a. Nasmyth’s membrane).

Anodontia:

Refers to the total lack of tooth | development.

Hypodontia:

Denotes the lack of development | of one or more teeth.

Oligodontia:

Indicates the lack of formation of six or more teeth (a subdivision of hypodontia).

Hyperdontia:

The development of an increased number of teeth (the additional teeth are termed supernumerary).

Supernumerary Teeth:

Defect that originates during I nitiation Stage that results in development of one or more extra teeth.

Mesodens:

The most common manifestation of | supernumerary tooth formation.

Odontoma:

originates during the I nitiation Stage and results in multiple small fragments of tooth structure consisting of dentin, enamel, cementum or any combination.

Complex Odontoma:

Comprised of a conglomerate mass of enamel and dentin that bears no anatomic resemblance to a tooth.

Compound Odontoma:

Comprised of multiple, | small tooth-like structures.

Taurodontism:

An enlargement of the body and pulp chamber of multirooted teeth with apical displacement of the bifurcation, i.e., an exceptionally long root trunk with very short roots

Dilaceration:

defined as an abnormal angulation | or bend in the root.

Gemination:

Defect that originates during Cap Stage of development that results in large single- rooted tooth with one pulp cavity and exhibits “twinning”in crown area.

gemination vs fusion

Gemination: Tooth count is normal when the double tooth is counted as one. Fusion: Refers to a double tooth in which the tooth count reveals a missing tooth when the double tooth is counted as one.

Concrescence:

Defect occurring during Apposition and M aturation stages that results in union of root structure of two or more teeth by cementum.

Tubercle Formation:

Defect occurring during Cap Stage of development that results in an extra cusp due to effects on enamel organ

Dentigerous Cyst (a.k.a. Follicular Cyst):

Originates by separation of the dental follicle (dental sac) from the crown of an unerupted tooth. The cyst is attached at the CEJ. This cyst type comprises 20% of all jaw cysts.

Odontogenic Keratocyst (OKC) arises from

the cells rests of the dental lamina (also called rests of serres)

Odontogenic Keratocyst (OKC) constituted --% of all odontogenic cysts

3-11%

Odontogenic Keratocyst (OKC): 60% of all cases are diagnosed in patients between the ages of ---

10-14 years

Odontogenic Keratocyst (OKC): 65% of cases are located in the

mandible

Odontogenic Keratocyst (OKC) are --- cysts

expanding

Odontogenic Keratocyst (OKC) are located in the posterior mandible often present as

multi ocular lesions

Odontogenic Keratocyst (OKC): --- --- is the treatment of choice, however there is a recurrence rate of approximately --%

surgical removal | 30

Odontogenic Keratocyst

Cyst wall consists of a 6-8 cell layer of stratified squamous epithelium with parakeratosis at the luminal surface. The lumen is often filled with keratin. The presence of inflammation will generally cause epithelial proliferation and pallisading of the basal cell layer.

Ameloblastoma:

The most common neoplastic lesion arising from odontogenic epithelium. Considered a slow growing, locally invasive tumor. Lesions have a multilocular or “soap bubble”appearance on radiographs. These tumors are radio-resistant.