Tooth development and anomalies of teeth (odontogenic tumors)

Question 1

Tissues of the tooth

Answer 1

dentin, enamel, cementum, pulp

Question 2

periodontum structures

Answer 2

gingiva, PL, cementum, aveolar bone

Question 3

stages of tooth development

Answer 3

initiation>bud>cap>bell>apposition>maturation

Question 4

basic events of tooth developmental stages

Answer 4

 Initiation: Cellular Induction
 Bud Stage: Cellular Proliferation
 Cap Stage: Proliferation, Differentiation
and Morphogenesis
 Bell Stage: Proliferation, Differentiation
and Morphogenesis
 Apposition: Induction and Proliferation, growth of mineralized tissues
 Maturation: Maturation

Question 5

ectoderm/mesenchyme (neural crest cells) interactions of tooth development, when?

Answer 5

Epithelium (ectoderm) plays an “instructional”role
during the pre-tooth bud 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 mesenchyme, and the mesenchyme, in turn,
specifies the tooth type (incisor vs. molar) and
nature of the product produced by the epithelium
(i.e., enamel matrix).

Question 6

tooth development flow chart from the bilaminar germ disc

Answer 6

Question 7

induction stage of tooth development, when?

structures involved?

Answer 7

weeks 6-7
► Oral Ectoderm
► Neural Crest Cells
► Dental Lamina
• Oral ectoderm (epithelium) invaginates into 
the mesenchyme, and is now 
called the dental lamina.
• The lamina is separated 
from the surrounding 
mesenchyme by a basement 
membrane

Question 8

bud stage

Answer 8

approx. 7th week
vestibule begins to form via apoptosis of mesenchymal cells, makes room for oral ectoderm invagination> dental lamina still forming (prolif of oral ectoderm)

Question 9

early cap stage, time? what forms?

Answer 9

weeks 9-10
apoptosis will form the buccal vestibule
dental lamina forms outer dental/enamel epithelium and early stellate reticulum

Question 10

cap stage, when? events? what is formed?

Answer 10

week 11
enamel organ formed from the dental lamina, opposite side the BM, the dental papilla begins to form but is undif at this stage.
enamel organ layers: outer/ inner enamel epithelium, and the stellate reticulum formed
dental follicle will begin to surround the entire structure

Question 11

bell stage, weeks? what can be seen?

Answer 11

14-18 weeks
all layers of enamel organ can be seen: inner/outer epithelium, strantum intermedium, stellate reticulum
dental lamina, papilla and follicle all present

Question 12

function of the external enamel epithelium, cell shape

Answer 12

protective barrier, cuboidal

Question 13

function of internal enamel epithelium, cell shape

Answer 13

dif into ameloblasts, cuboidal

Question 14

function of stellate reticulum, cell shape

Answer 14

supportive func in enamel production, star shaped cellular network in enamel organ

Question 15

strantum intermedium function, cell shape

Answer 15

supportive of enamel production: produce alkaline phosphatase for mineralization, compressed cuboidal cells

Question 16

dental sac function (what kind of fiber, gives rise to?)

Answer 16

collagen fibers around enamel organ, becomes PDL/cementum/bone

Question 17

dental papilla, gives rise to?

Answer 17

cells nearest to IEE, spereated by BM, outer cells will dif into odontoblasts/. inner cells become pulp

Question 18

cervical loop, site of what in adult?

Answer 18

Junction of the outer
& inner enamel epithelia
Site of cemento-enamel
junction (CEJ) in the adult     
tooth (a.k.a., cervix)

Question 19

hertwig’s epithelial root sheath, determines? when is it removed?

Answer 19

Fusion and apical 
extension of the 
outer and inner
enamel epithelia.
Determines the outline of
the root dentin and the
number of roots a tooth
will have (epithelial diaphragm).  It is removed
before the cementum is
laid down

Question 20

modification to hertwig’s (normal development not mutation)

Answer 20

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

Question 21

termination point of enamel formation, dentin growth pushes tooth?

Answer 21

Enamel formation stops at the termination of the enamel organ. Dentin
formation continues, and pushes the tooth occlusally.

Question 22

root development completion time, events within root

Answer 22

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.

Question 23

appostional growth

Answer 23

ameloblasts and odontoblasts interaction
cuboidal IEE cells grow to columnar and become ameloblasts with receptors to attract preodontoblasts (fibronectin)> line up opposite of one another> odonotblast dif> secrete mantle dentin> detected by ameloblasts, secrete enamel
as ameloblasts secrete enamel they grow away from the BM
odontoblast remain attached to the BM via processes as they secrete dentin, porcesses= dentin tubules, used to mineralize the predentin

Question 24

mantle dentin, when? kinds of fibers? stimulates?

Answer 24

formed in appostional stage, first dentin formed
usually thin layer
collagen I and III perpindicular to DEJ
presence will stim ameolblasts to secrete enamel

Question 25

Answer 25

Question 26

migration of ameloblasts and odontoblasts paths

Answer 26

Migration of ameloblasts peripherally

Migration of odontoblasts inward (centrally)

Question 27

active vs. non active ameloblasts

Answer 27

 Actively secreting 
ameloblasts are tall
columnar cells
 Inactive (a.k.a. reduced) 
ameloblasts are short 
columnar or elongated 
cuboidal cells

Question 28

primary cuticle

Answer 28

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).

Question 29

anodontia

Answer 29

Refers to the total lack of tooth

development (no teeth)> due to dental lamina or enamel organ not forming, some cases of ectodermal dysplasia

Question 30

hypodontia, most commonly affects which teeth?

Answer 30

Denotes the lack of development
of one or more teeth.
also due to dental lamina/enamel organ not forming
most commonly 3rd molar missing followed by max LI

Question 31

oligodontia

Answer 31

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

Question 32

hyperdontia

Answer 32

The development of an increased
number of teeth (the additional 
teeth are termed supernumerary).
many possible kinds 
formation of additonal dental lamina/enamel organs

Question 33

supernumerary teeth, originates at what stage?

Answer 33

Defect that
originates during the Initiation Stage that
results in the development of one or more extra
teeth (additional enamel organ/dental lamina).

Question 34

mesodens, common?

Answer 34

The most common manifestation of
supernumerary tooth formation.
addtional tooth btwn the max CI

Question 35

4th molars

Answer 35

possible supernumerary tooth form

Question 36

odontoma, origin at what stage? kinds? treatment? can lead to?

Answer 36

originates during the Initiation Stage
and results in multiple small fragments of tooth
structure consisting of dentin, enamel,
cementum or any combination.
complex: do not resemble teeth
compound: resemble teeth
must be removed=they are invasive and can thin jaw bone leading to pathological fractures

Question 37

complex odontoma

Answer 37

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

Question 38

compound odontoma

Answer 38

Comprised of multiple,

small tooth-like structures.

Question 39

abnormal root development cause

Answer 39

issues with epithelial diaphragm in hertwig’s root sheath> can lead to additional roots

Question 40

taurodontism, cause?

Answer 40

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.
caused by issue with Hertwig’s/epithelial diaphragms

Question 41

dilacerations, cause?

Answer 41

defined as an abnormal angulation
or bend in the root.
due to hertiwgs/epthelail root sheath deviation

Question 42

Lack of root formation?

Answer 42

possible, only enamel organ products produced
no hertwig’s root formation
IEE and OEE join at cerival loop and stop

Question 43

shortened roots cause (not from development)

Answer 43

not always hertwigs but can also be cause by accelerated orthodontics causing root resorbtion

Question 44

gemination, origin point?

Answer 44

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.
tooth count is normal

Question 45

fusion, origin point?

Answer 45

cap stage 
Refers to a double tooth in which
the tooth count reveals a missing tooth
when the double tooth is counted as one.
tooth count will be one less

Question 46

concresence, origin point? extraction complication?

Answer 46

Defect occurring during Apposition, hypercementosis
and Maturation stages that results in union of root
structure of two or more teeth by cementum
extraction leads to large perio defects

Question 47

extra cusp formation, origin? what is defective?

Answer 47

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

Question 48

dentigerous cyst, origin point? incidence?

Answer 48

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

Question 49

Keratocystic Odontogenic Tumor, origin, % of all odontogenic cysts , age range, common location, effect on bone, often present as, treatment/recurrence?

Answer 49

 Arises from the cells rests of the dental lamina if stimed in right way (also called rests of Serres).
 The OKC constitutes 3% to 11% of all odontogenic cysts.
 60% of all cases are diagnosed in patients between the
ages of 10 and 40 yrs.
 65% of all cases are located in the mandible.
 OKCs are bone expanding cysts=invasive
 OKCs located in the posterior mandible often present as
multilocular lesions.
 Surgical removal is the treatment of choice. However,
there is a recurrence rate of approximately 30%.

Question 50

common location of odontogenic keratocyst

Answer 50

most common in posterior mandible

Question 51

odontogeinc cyst structure

Answer 51

Cyst wall consists of a 6-8 cell layer of stratified
squamous epithelium with parakeratosis (nuclei throughout the epithelial layer) at the luminal surface. The lumen is often filled with keratin.
The presence of inflammation will generally
cause epithelial proliferation and palisading of the
basal cell layer.
swirls of keratin present in the section

Question 52

macro/microdontia, micro seen with? example?

Answer 52

enlarged teeth or small teeth
microdontia can be seen with cleft lips or palates, Ehler’s-Danlos, hypopititary, ectoderm disorders
Peg max LI

Question 53

ameloblastoma, commonly found? epithelial components?

Answer 53

abnormal prolif of the enamel organ components, results in odontogenic tumor
commonly in mandible
mainly epithelial components resemble preameloblasts
multilocular