Amelogenesis

Question 1

what are 3 Proteins and their associated genes Contributing to Appositional Growth in Thickness of the Enamel Layer

Answer 1

1) amelogenin= AMELX, AMELY
2) enamelin =ENAM, 4q21
3) ameloblastin =AMBN, 4q21

Question 2

amelotin and gene?

Answer 2

AMTN

*Proteins Related to Basal Lamina Covering Maturing and Mature Preeruptive Enamel

Question 3

Tuftelin

Answer 3

legacy protein

Question 4

proteinases: enamelysin, MMP20, kallikrain4

Answer 4

Proteins Involved in Postsecretory Processing and Degradation of Amelogenins and Nonamelogenins

Question 5

what do teeth look like when enamel formatio nis disturbed?

Answer 5

teeth become characterized by

distinctive bands of malformed enamel

Question 6

what do teeth look like with tetracycline-induced disturbances?

Answer 6

Tetracycline antibiotics are incorporated into mineralizing tissues LIKE ENAMEL
*result in a band of brown pigmentation or even total pigmentation. Hypoplasia or absence of enamel also may occur

Question 7

what do teeth look like with fluoride ion can interference?

Answer 7

• Chronic ingestion of fluoride ion concentrations in excess of 5 ppm
• interferes sufficiently with ameloblast function
• PRODUCES MOTTLED ENAMEL
• very unsightly white patches of hypomineralized and altered enamel but STILL RESISTS CARRIES

Question 8

What are the genes associated with amelogenesis imperfecta?

Answer 8

AMELX, ENAM, DLX3, FAM83H, MMP-

20, KLK4, and WDR7

Question 9

What is amelogenesis imperfecta?

3 clinical correlates

Answer 9

X-linked, autosomal inherited defect

• disrupts the structure and clinical appearance of enamel
  1) hypoplastic
  2) hypocalcified
  3) hypomature defective enamel

Question 10

what is surprising about AMBN gene?

Answer 10

mutant mice show major defects in enamel formation but NO amelogenesis imperfecta has been linked to it

Question 11

what is amelogenesis? how many steps?

Answer 11

It enamel formation and considered a TWO STEP process

1) secretory stage
* * transitional stage
3) maturation stage

Question 12

enamel organ is made up of what cell layers in secretory stage of amelogenesis?

Answer 12

1) ameloblasts
2) stratum intermedium
3) stellate reticulum
4) outer enamel epithelium

Question 13

enamel… basic facts you need to know

Answer 13

• hardestcalcified matris of the body
• cannot renew itself becuz ameloblasts that make it are lost as the tooth erupts
• ALMOST totally absent of organic material
• has extremily long crytals

Question 14

fully formed enamel is ___% inorganic mineral

Answer 14

96% inorganic mineral and 4% organic material/water

Question 15

inorganic mineral is composed of?

Answer 15

non-stoichiometric carbonate-substituted hydroxyapatite, contains trace amounts of: fluoride (F), sodium (Na),
magnesium (Mg), zinc (Zn) and strontium (Sr)

Question 16

why is dentin necessary to maintain enamel?

Answer 16

the high mineral content of enamel makes it hard and able to withstand mechanical force BUT its makes enamel BRITTLE so the underlying RESILIENT layer of dentin is necessary to maintain integrity

Question 17

what are the fundamental organizational units of mammalian enamel? shape?

Answer 17

1) rods= hexagonal and prism-LIKE (rods do
not have a regular geometry and hence are not prismatic)
2) interrod= interprismatic substnace

Question 18

Enamel is built from closely packed and long, ribbon-like?

Answer 18

carbonate apatite crystals

*measuring 60-70nm in width and 25-30nm in thickness AKA REALLY LONG

Question 19

young vs old enamel?

Answer 19

• young= hexagonal symmetry
• old= no longer hexagonal but exhibit an irregular outline as they press together ( grouped together as rod or interrod enamel)

Question 20

tomes processes

location of rods and interrods

Answer 20

distal end of cells
*when ameloblasts deposit and mineralize matrix and retreat from DEJ
RODS ON DISTAL TIP
INTERROD ON PROXIMAL SIDES

Question 21

During the long-lasting process of enamel maturation, ameloblasts cyclically change structure and function between?

Answer 21

ruffled ended (RA) and smooth-ended (SA) ameloblasts!!!

Question 22

difference between ruffled-ended (RA) and smooth-ended (SA) ameloblasts?

Answer 22

• *RA= add mineral to the immature enamel

* SA= removes degraded matrix proteins and water

Question 23

During maturation, an additional 25% of the cells ____?

Answer 23

die

Question 24

Once mineralization is complete, the ameloblasts again shorten and become?

Answer 24

protective (reduced) ameloblasts

Question 25

FIRST during the pre-secretory stage, differentiating ameloblasts acquire?

Answer 25

*phenotype
*change polarity
*develop an extensive protein synthetic
apparatus
*prepare to secrete the organic matrix of enamel

Question 26

SECOND during the secretory stage ameloblasts

Answer 26

elaborate and organize the entire enamel thickness = very ordered tissue

Question 27

THIRD during the maturation stage, ameloblasts

Answer 27

modulate and transport specific ions

Question 28

Enamel formation begins when?

involves?

Answer 28

early crown stage

*involves the differentiation of IEE first at the tips of the cusp

Question 29

enamel formation starts?

Answer 29

at the tips of cusps and then goes down the slopes of the crown until all cells of the epithelium have differentiated into ameloblasts

Question 30

differentiating ameloblasts are located where?

Answer 30

away from the blood vessels that lie outside the IEE