Amelogenesis

Question 1

_____ of enamel is primarily related to a delay
in the removal of amelogenin during maturation. Birthing
difficulties and nutritional deficiencies also commonly disturb development.

Answer 1

Hypomineralization

Question 2

The _____ induces differentiation of odontoblasts

Answer 2

Inner enamel epithelium

Question 3

_____ is an acellular tissue with no collagen in matrix; formation involves both secretory and resorptive activities of ECTODERMALLY derived cells; hardest tissue in body

Answer 3

Enamel

Question 4

____ exhibits thixotropic properties (ability to flow under pressure)

Answer 4

Amelogenin

Question 5

___ stage of amelogenesis is characterized by decrease in height, less organelles, ruffled border to increase surface area; removes excess water and proteins and adds minerals to harden the enamel

Answer 5

Maturation stage

Question 6

____ is an acidic, phosphorylated, and glycosylated protein; largest of enamel matrix proteins; restricted to enamel rod area; its phosphorylated nature and initial accumulation near the growing ends of crystals suggest that enamelin plays a role in crystal growth and nucleation

Answer 6

Enamelin

Question 7

Enamel is ____ times harder than dentin

Answer 7

5x

Question 8

The ____ represents an exaggerated hypomineralized

striae of Retzius that forms at birth

Answer 8

neonatal line

Question 9

How is the enamel rod oriented in the tooth?

Answer 9

Parallel with the long axis of the tooth

Question 10

_____ is an optical phenomenon
produced by changes in direction of the enamel rods.
Seen only in ground histologic sections viewed by
reflected light.

Answer 10

Hunter-Schreger Bands:

Question 11

Incremental lines produced by
periodic constriction of Tomes
process associated with
corresponding increase in the
face forming the interrod enamel.
Represents about 4-8 days of
rhythmic enamel matrix
apposition.

Answer 11

Striae retzius

Question 12

Defective enamel matrix
deposition which, in turn, voids the possibility of
enamel mineralization. Although there are multiple
types, the more common
types are autosomal dominant inherited.

Answer 12

Amelogenesis Imperfecta:

Question 13

______ then induces formation and proliferation of the dental lamina

Answer 13

Neural crest cells

Question 14

___ stage of amelogenesis is characterized by formation of Tome’s processes to secrete enamel; contains secretory granules and shift down to help mineralize enamel matrix; alkaline phosphatase are secreted from stratum intermedium to help in mineralization

Answer 14

Secretory stage

Question 15

The gradient of cellular differentiation, matrix secretion, and mineralization during tooth development is ______ to ____ for individual teeth

Answer 15

Coronal to apical

Question 16

Enamel pearls most often involve what teeth?

Answer 16

maxillary molars

Question 17

External (surface) manifestations of

the Striae of Retzius.

Answer 17

Perikymata:

Question 18

(a.k.a. primary enamel cuticle or Nasmyth’s
membrane) is comprised of the remnants of the reduced
enamel epithelium.

Answer 18

Enamel cuticle

Question 19

___ stage of amelogenesis is characterized by columnar or cuboidal cell mostly inactive

Answer 19

Morphogenic stage

Question 20

The angle of the _____ determines the angle at which the enamel will form

Answer 20

Tome’s process

Question 21

____ initially found throughout the rod and interrod enamel; located in rod sheaths

Answer 21

Sheathlin

Question 22

What are the 4 TRAP proteins of enamel?

Answer 22

Amelogenin, Enamelin, Tuftelin, and Sheathlin

Question 23

____ secrete the mantle layer of dentin

Answer 23

Odontoblasts

Question 24

____ individual ameloblasts contribute to the composition of one enamel rod

Answer 24

4

Question 25

(a.k.a. acquired pellicle or salivary pellicle)

is comprised of glycoprotein precipitates derived from saliva and/or gingival crevicular fluids.

Answer 25

Enamel pellicle

Question 26

In ____, the Ca hydroxyapatite crystals are extremely large, highly oriented, and packed into rod-like structures; although 96% mineral, the basic rod structure exhibits some degree of flexibility

Answer 26

Enamel

Question 27

Enamel thickness ranges from ____ over the cusps

Answer 27

2 – 2.5 mm

Question 28

_____ of enamel is generally induced by infectious diseases of childhood, e.g., measles, rheumatic fever, mumps, etc., which leave a defect in those parts of the teeth actively developing at the time of the infection.

Answer 28

Hypoplasia

Question 29

A deep invagination of the crown or root that is lined
with enamel.
• Prevalence rate of 0.4% to 10% of all patients.
• Most commonly involves the maxillary incisor.

Answer 29

Dens-In-Dente

Question 30

Hypomineralized areas of enamel at

the DEJ that are rich in enamelin and tuftelin.

Answer 30

Enamel Tufts:

Question 31

that occur during apposition and maturation stages of tooth development due to displacement of ameloblasts to root surface.

Answer 31

Enamel Pearls & Cervical Enamel Projections (CEP): Defects

Question 32

____ is most commonly found in cusp tips.
Enamel rods appear to be twisted in a complex
arrangement. Very resistant to fracture and abrasion.

Answer 32

Gnarled Enamel –

Question 33

___ enamel occurs as a result of a diet containing
relatively high levels of fluoride. Severe enamel fluorosis
may manifest as opaque areas, light-brown mottling, and
surface pitting.

Answer 33

Mottled

Question 34

____ is the first formed dentin; its presence stimulates enamel formation

Answer 34

Mantle dentin

Question 35

The gradient of cellular differentiation, matrix secretion, and mineralization during tooth development is ______ to ____ for the overall dentition

Answer 35

Anterior to Posterior

Question 36

___ stage of amelogenesis is characterized by all layers reduce together; reduce enamel epithelium, forms cuticle (protects enamel), and the rest joins junctional epithelium when the tooth erupts

Answer 36

Protective stage

Question 37

The process of ______ explains that one process affects the second process and this second process affects the first in turn

Answer 37

Reciprocal induction

Question 38

____ appears restricted to the DEJ in enamel tufts; though to play a role in induction, the initiation of mineralization, and possibly functions as a junctional protein linking enamel and dentin; linking protein

Answer 38

Tuftelin

Question 39

___ are Cracks extend from the enamel
surface to variable distances into the enamel.
May extend into the dentin

Answer 39

Enamel Crack:

Question 40

The _____ eventually separates into an outer and inner dental epithelium

Answer 40

Dental lamina

Question 41

_____ on each rod
represent 24 hours of enamel
matrix production,

Answer 41

Cross striations

Question 42

Pre-tooth bud stage _____ specifies the “dental nature” of the underlying mesenchyme (neural crest cells)

Answer 42

Ectoderm

Question 43

CEPs most often involve what teeth?

Answer 43

mandibular molar

Question 44

___ stage of amelogenesis is characterized by cell starting to increase in size and becomes a tall columnar cell; nucleus becomes polarized; more organelles start forming like mitochondria and ER; junctional complexes form (cells start lining up and become joined to one another); induction of odontoblasts, dentin formation, and basement membrane is eliminated

Answer 44

Differentiation stage

Question 45

_____ Represent extensions of
odontoblastic processes and tubules across the basal
lamina during initial stages of matrix formation.

Answer 45

Enamel Spindles:

Question 46

____ is Hypomineralized areas of enamel
extending from the DEJ for considerable distances
into the enamel. May be involved with smooth
surface caries.

Answer 46

Enamel Lamellae:

Question 47

The perikymata (enamel surface manifestations of the striae of Retzius) are also known as the _______

Answer 47

imbrication lines of

Pickerill

Question 48

Once the the mantle layer of dentin is formed, ____ differentiation is initiated and amelogenesis begins shortly thereafter

Answer 48

Ameloblasts