NBDE ANATOMICAL SCIENCE: Tooth Development

Question 1

The dental lamina, a thickening of oral epithelium that produces the swellings of the enamel organs is first seen histologically around _ week in utero

Answer 1

6th week = dental lamina

Question 2

by the __ week after conception the primitive mouth (stomodeum) has formed

Answer 2

3rd week

Question 3

after the primitive mouth (stomodeum forms) in the 3rd week. Over the next few weeks the _ develop

Answer 3

tongue, jaws, and palate

Question 4

during the 6-8th week the formation of _ commences

Answer 4

teeth

Question 5

by the __th week in utero, all of the primary (deciduous) incisors, canines, and molars are descernible

Answer 5

6th

Question 6

tooth development appears to be initiated by the __inductive influence on the overlying ectoderm

Answer 6

mesenchymal

Question 7

early in the 6th week the oral epithelium thickens into a U-shaped band called the

Answer 7

dental lamina

Question 8

at certain points on the dental lamina, the ectodermal cells proliferate and produce swellings that become the _

Answer 8

enamel organ

Question 9

at certain points on the dental lamina, the ectodermal cells proliferate and produce swellings that become the

Answer 9

enamel organ

Question 10

inside the depression of the enamel organ an area of condensed mesenchyme becomes the

Answer 10

dental papilla

Question 11

surrounding both the enamel organ and dental papilla is a capsule-like structure of mysenchyme called the

Answer 11

dental sac (follicle)

Question 12

when does the enamel organ separate from the dental lamina?

Answer 12

after the first layer of dentin is deposited

Question 13

each tooth is the product of 2 tissues that interact during tooth development: the _ and the_

Answer 13

oral epithelium and the underlying ectomesenchyme

Question 14

the oral epithelium grows down into the __ and forms small areas of condensed __ which become tooth germs

Answer 14

ectomesenchyme

mesenchyme

Question 15

name the components of a tooth germ

Answer 15

enamel organ
dental papilla
dental sac

Question 16

the primordium of the permanent succedaneous tooth lingual to the primary tooth germ is in which stage

Answer 16

bud stage

Question 17

when enamel maturation is completed, the ameloblast layer and the adjacent papillary layer regress together constitute the __ that covers the tooth thru eruption

Answer 17

reduced enamel epithelium

Question 18

the reduced enamel epithelium remains until the tooth

Answer 18

erupts

Question 19

as the tooth passes through the oral epithelium the part of the reduced enamel epithelium situated incisally is ___ while the cervical interacts with the oral epithelium to form

Answer 19

destroyed

junctional epithelium

Question 20

the junctional epithelium (epithelium attachment) attaches to gingival tissues via

Answer 20

hemidesmosomes

Question 21

the reduced enamel epithelium is formed after the

Answer 21

completion of enamel apposition when enamel organ undergoes compression of its many layers on the enamel surface

Question 22

epithelial cells of the inner and outer epithelium proliferate from the cervical loop of the enamel organ to form a double layer of cells known as

Answer 22

Hertwig’s epithelial root sheath

HERS

Question 23

the structure responsible for root development is the

Answer 23

cervical loop

Question 24

the cervical loop is the most cervical portion of the

Answer 24

enamel organ

Question 25

the cervical root is a bilayer rim that consists of only _ of the enamel organ

Answer 25

inner and outer enamel epithelium

Question 26

Hertwig's sheath is an epithelial diaphragm that is derived from the

Answer 26

inner and outer enamel epithelium of the enamel organ

Question 27

after crown formation the Hertwig's sheath grows down and shapes the root of the tooth and induces formation of

Answer 27

root dentin

Question 28

1. uniform growth of Hertwig's sheath will result in the formation of a _ rooted tooth 2. medial outgrowths or evaginations of the Hertwig's sheath will produce _ rooted teeth

Answer 28

1. single | 2. multi

Question 29

1. after the first root dentin is deposited, the cervical portion of Hertwig's sheath breaks down and this new dentin comes into contact with the ___ 2. this interaction of dentin and the dental sac stimulates cells to differentiate into

Answer 29

dental sac | 2. cementoblasts to produce cementum = cementogenesis

Question 30

communication bw pulp tissue and the PDL other than thru the root apex =

Answer 30

accessory canals

Question 31

accessory canals are the result of a localized failure in the formation of

Answer 31

Hertwig's sheath during embryonic stages of tooth formation = leads to failure of odontoblastic differentiation and dentin formation

Question 32

an __ is a non-neoplastic excrescence of enamel where enamel is not supposed to be, ex on root surface

Answer 32

enamel pearl

Question 33

enamel pearls r usually found

Answer 33

bw roots (furcation) of molars

Question 34

most common location of an enamel pearl is the furcation areas of

Answer 34

max and MD 3rd molar roots

Question 35

Enamel pearls are formed from

Answer 35

Hertwig's epithelial root sheath

Question 36

the cervical lop is composed of the most cervical portion of the __ and is responsible for _

Answer 36

enamel organ | root development

Question 37

Hertwig's epithelial root sheath is formed from the _ of the cervical loop and is responsible for the _ of roots and induction of _

Answer 37

elongation shape root dentin

Question 38

inner enamel epithelium differentiate into

Answer 38

ameloblasts

Question 39

Korff's fibers are found in the

Answer 39

pulp

Question 40

what forms the middle part of the enamel organ

Answer 40

stellate reticulum

Question 41

name the 4 layers of the enamel organ

Answer 41

outer enamel epithelium (OEE), Inner enamel epithelium (IEE), Stratum Intermedium (SI), Stellate reticulum(SR)

Question 42

this layer outlines the shape of the future developing enamel organ

Answer 42

outer enamel epithelium (OEE),

Question 43

the innermost cellular layer of the enamel organ that will become ameloblasts and produce enamel

Answer 43

Inner enamel epithelium (IEE)

Question 44

lies lateral to the Inner enamel epithelium (IEE) and is thicker. this layer is essential to enamel formation since it prepares nutrients for the ameloblasts of the IEE

Answer 44

stratum intermedium

Question 45

this area is the central core of the enamel organ and the bulk. contains a lot of intercellular fluid (mucus type fluid rich in albumin) and is lost just before enamel deposition

Answer 45

stellate reticulum

Question 46

after enamel formation all 4 layers of enamel organ become one and form the _ which is impt in the formation of the _

Answer 46

reduced enamel epithelium | DEJ

Question 47

the DEJ is an area where the _ and _ come together as the tooth erupts into the mouth

Answer 47

enamel and epithelium

Question 48

the enamel and epithelium come together to form the __, which later migrates down the tooth to assume normal position

Answer 48

initial junctional epithelium (epithelial attachment)

Question 49

name the 8 stages of tooth development

Answer 49

initiation, bud, cap, bell, apposition, calcification, eruption, attrition

Question 50

induction is the main process in

Answer 50

initiation

Question 51

in initiation (6-7th week) ectoderm lining stomodeum gives rise to oral epithelium and then to dental ___

Answer 51

lamina

Question 52

congenital absence of teeth (anodontia) and supernumerary teeth result from an interruption in what stage of tooth development

Answer 52

initiation

Question 53

bud stage (8th wk): growth of dental lamina into a bud that penetrates the ectomesenchyme = __ is the main process

Answer 53

proliferation

Question 54

tooth germ forms in _ stage

Answer 54

cap stage

Question 55

dens in dente, germination, fusion and tubercle formation occurs in which phase of tooth development

Answer 55

cap stage

Question 56

proliferation, differentiation and morphogenesis are main processes in which stage

Answer 56

cap stage

Question 57

11-12th week is the __ stage = final shaping of tooth. cells differentiate into specific tissue forming cells (ameloblast, odontoblast, cementoblast, fibroblast) in the enamel organ.

Answer 57

bell

Question 58

Histodifferentiation and morphodifferentiation are main processes involved in _

Answer 58

bell stage

Question 59

macrodontia and microdontia occur in _ stage

Answer 59

bell

Question 60

deposition of specific dental tissues (enamel/dentin/cementum/pulp) in this stage

Answer 60

apposition

Question 61

enamel dysplasia, concrescence and enamel pearls occur in _ stage

Answer 61

appostion

Question 62

Amelogenesis imperfect and dentinogenesis imperfect occur in _ stage

Answer 62

bell

Question 63

in adults the epithelial cell rests of Malassez persist next to the root surface within

Answer 63

the PDL

Question 64

rest of Malassez are functionless but are the source of epithelial lining of dental __ that develop in rxn to inflammation of the PDL

Answer 64

cysts

Question 65

the rests of Malassez are remnants of __

Answer 65

Hertwig's epithelial root sheath found in PDL They are discrete clusters of residual cells from Hertwig's epithelial root sheath (HERS) that didn't completely disappear

Question 66

Some rest of Malassez degenerate and others calcify and become__

Answer 66

cementicles in the PDL

Question 67

2 purposes of Hertwig's epithelial root sheath

Answer 67

-shape root and induce dentin formation by stimulating odontoblasts

Question 68

the continuity of Hertwig's epithelial root sheath must be broken in order for _ to be deposited

Answer 68

cementum

Question 69

Hertwig's epithelial root sheath forms _ in the PDL when its functions have been accomplished

Answer 69

rests of Malassez

Question 70

Hertwig's root sheath does not have all 4 layers of the enamel organ. it only has which 2?

Answer 70

outer and inner enamel epithelium. does not have stratum intermedium or stratum reticulum

Question 71

the structure responsible for root development is the _

Answer 71

cervical loop (most cervical part of enamel organ)

Question 72

histologically the dentin in the root is distinguished from the dentin of the crown by the presence of

Answer 72

granular layer of Tomes = only under the surface of dentin where the root is covered by cementum. only seen in ground sections.

Question 73

granular layer of Tomes increases as you go

Answer 73

toward the apex from the DCJ

Question 74

the granular layer of Tomes appears

Answer 74

spotty

Question 75

globular dentin

Answer 75

areas of both primary and secondary mineralization of dentin

Question 76

interglobular dentin

Answer 76

UNMINERALIZED or HYPOMINERALIZED dentin where globular zones of mineralization (calcospherites) have failed to fuse

Question 77

interglobular dentin is seen most frequently in the _ dentin just below the mantle dentin where the pattern of mineralization is largely globular

Answer 77

circumpulpal

Question 78

which product is NOT ectodermal origin: ``` junctional epithelium enamel hertwig's epithelial root sheath pulp ameloblasts ```

Answer 78

pulp

Question 79

the dental organ is aka

Answer 79

tooth germ

Question 80

is dental organ the same thing as enamel organ

Answer 80

no!

Question 81

dental organ aka tooth germ is made of 3 things

Answer 81

dental sac (follicle) dental papilla enamel organ

Question 82

enamel organ is formed from __ epithelium

Answer 82

oral epithelium which is derived from ectoderm

Question 83

the enamel organ will give rise to __ and eventually forms _

Answer 83

enamel | Hertwig's epithelial root sheath (HERS)

Question 84

Dental follicle (aka dental sac) is formed from __ which is derived from __

Answer 84

mesenchyme (ectomesenchyme) | neural crest cells

Question 85

dental papilla is formed from __ which is derived from __

Answer 85

mesenchyme (ectomesenchyme) which is derived from neural crest cells

Question 86

both the dental papilla (forms pulp and dentin) and the dental sac (follicle forms PDL, cementum and alveolar bone proper) are derived from

Answer 86

mesenchyme (ectomesenchyme) derived from neural crest cells