ex1 enamel tissue

Question 1

why should one be cautious aobut rubber dammng a tooth?

Answer 1

use of rubber dams requeire cuastion bc they deprive the tooth enamel of necessary water. prolonger isolation would dry out the enamel.

Question 2

T/F enamel needs a wet environment to survive

Answer 2

True. Enamel requires a wet environment

Question 3

of the following 3 forces.. which is considered a normal force?
abrasion, attrition, erosion

Answer 3

attrition - the slow wearing away of tooth substnace (ex/ from the forces of mastication) is considered a normal force on enamel

Question 4

T/F when demineralziation exceeds mineralization, cavitation results

Answer 4

True. when demineralization exceeds mineralization (as allowed for by neutral pH as facilitated by saliva)) then cavitation results

Question 5

Bone, cementum, dentin and enamel are the 4 mineralized tissues.. which of these does not contain collagen?

Answer 5

Of the four minealzed tissues, only ENAMEL does not have any collagen. the other 3, bone, cemtenum, and dentin contain collegen (moslty type 1 collagen)

**NOTE, collagen is NOT dissovlved by acid.. however, enaml does not have any collagen..

Question 6

How is water distributed around the enamel crytals and proteins?

Answer 6

water is distributed around the enamel crytals and proteins by way of MICROPORES which allows passage of small molecules (such as water)

Question 7

Do systemic changes to the body associated with age impact the state of tooth enamel?

Answer 7

Yes. systemic changes to the body due to age DO impact the state of tooth enamel – enamel is alos subject to attrition, darkening color, surface composition changes, reduced porosity (so less water which it needs!), etc

Question 8

At the CEJ – how do the cementum and enamel layers meet-up?

Answer 8

Most commonly at the CEJ the cementum overlpas the enamel,second common = the cementum and enamel just meet-up, least common is where the cementum does not meet the enamel at all (a gap btweeen),

Question 9

At the CEJ, it is most common to see the enamel overlap the cementum

Answer 9

False. At the CEJ it is most common to see the cementum overlap the enamel, less common the just touch and meet-up, least common the cementum and enamel do not touch at all (gap) .. there is not really a scenario wher the enamel is on top of hte cementum

Question 10

why is the DEJ scalloped in shape?

Answer 10

The DEJ is scalloped in shape due to occlusal forces that have influenced it. The dentin is smooth in area that are non-load bearing

Question 11

T/F ameloblasts are seen as squamous epithelial cells

Answer 11

False. Ameloblasts are seen as tall columnar epithelial cells

Question 12

what is the name for the growth lines seen in enamel?

Answer 12

the growth lines seen in enamel are called the lines of Retzius

Question 13

what are the straie of Retzius

Answer 13

The striae (lines) of Retzius are the growht lines of enamel– these are present as the differnt subsequnet layers of enamel were decreted at differnt times (( so leaves rings with each secreted layer like a tree))

Question 14

T/F perikymata are lines that traverse bt the grooves formed by the lines of retzius (aka, the perikymata are almost poerpendicular in orientaiton of the lines of Retzius)

Answer 14

True. Perikymata are lines that are perpendicular to the groove formed by the growht lines of enamel called the lines of Retzius
(perikymata looks wave-like, along horizontally oriented on the tooth surface))

Question 15

How many ameloblasts does it take to form one enamel rod?

Answer 15

One ameloblasts forms one enamel rod and its rod sheath!

Question 16

descrbie the oritentation of the hydroxyapatite crytals within the enamel rods .. where are the HA most densely concetrated?

Answer 16

The HA crystals are oritented along the long axis of the ena,el rods. The hydroxyapatite crytals are most concetrated in the ceter/ core of the enamel rod

Question 17

describe the enamel sheath of the enamel rod

Answer 17

the enamel sheath is the outer surface of an enamel rod. It has a less dense concentration of HA crystals, and a higher concetration of organic AMELIN

Question 18

T/F it takes one ameloblast to secrete the interrod substance

Answer 18

False! It takes 2+ ameloblasts to secrete interrod substance (recall, the neighbors all contribute as the Tome’s process moves out of the Tome’s pit))

interrod substane runs bt the sheaths of enamel rods. The interrod suvstance has DENSE HA crystals which are orientaed in different directions than those in the rod sheath.

Question 19

In what orientation to the dentin do the enamel rods orient?

Answer 19

The enamel rods are oriented in opposition/ perpendicular to the dentin

Question 20

What are the interrod striations?

Answer 20

The interrod striations are seen in magnified histo pics, where there are darker lines throughout the enamel rod, perpendicular to the lines of therod sheath/interrod substnace. the interrod striations demark built up segments of enamel rod
– aka the rest period of an ameloblast is visible as a interrod striation

Question 21

T/F the rest period of an ameloblast can be seen as an interrod striation

Answer 21

True. The interrod striations are seen bt the built up segments of enamel rod - aka wher the ameloblast rested bt secretions of enamel rod

Question 22

Name the 3 hypomineralized enamel strucutres, and what is their general clinical significance?

Answer 22

The three hypomineralized enamel strucutres are the :

• -enamel lamella (surface enamel to deeper.. as far as DEJ)
• the enamel tufts (start at DEJ and extend itno enamel, contains tuftelin)
• • the enamel spindle.. extends from dentin across DEJ and into the enamel

all three of the hypominerlaized ena,el strucutres are clinically significant as they pose a pathway of caries spread ((esp from surface/ enamel staight to the dentin, where due to less minealziation, the caries exploseds ((recall, the progression of caries as 2 inverted triangles))

Question 23

which hypominerlaized enamel structure starts in the dentin and extends passed the DEJ into the enamel? what produces this structure?

Answer 23

The enamel spindle is a hypominerlaized ename;l strucutres that crosses from the dentin into the enamel (= pahway for caries!)

– the distal end of the odontoblast porcess produces the enamel spindle beofre any dentin or enamel is formed. this enamel spindle is trapped as the enamel forms around it

Question 24

which hypominerlaized enamel strucure starts at the surface enamel and extends as far as near the DEJ?

Answer 24

The enamel lamella is a hypomineralized enamel strucutre that starts at the surface enamel and extends as deep as the DEJ area (= highway for caries@ and esthetic staining))

Question 25

which hypominerlaized enamel structure starts at the DEJ and extends into the enamel? (hint: contains tuftelin, an enamel protein)

Answer 25

The enamel tuft is the hypominerlaized enamel structure that starts at the DEJ and goes into the enamel. Contians tuftelin

Question 26

what can be found inside the enamel lamella and how are thes structures clinically relevant?

Answer 26

Organic oral caivty debris or enamel proteins fill the hypominbealzied enamel strucutre of enamel lamellae. Clinically, the enamel lamallae are significant as they are a highway for caries to the DEJ. and for staining of hte tooth surface tht is estheticially unpleasant.

the enamel lamelle aextend for varying depths fromthe surface to the deeps.. they are longitudinally oriented

Question 27

Histologically, which enamel strucutre looks like a little wispy tail.. and where can this strucutre be seen?

Answer 27

Histologically, the enamel tufts are a hypominerlaized enamel strucutre tht looks likea wispy tail that is sttached to the DEJ and extends a shrot amount into the enamel.

These can help spread caries into the dentin (bad!)

Question 28

what do the spindles look like and where are htey found (histo)

Answer 28

The enamel spinsles are also found along the DEJ. The look like the freeze-lines of ice on glass.. up close, look like little flames coming off of the DEJ (similar in shape to the enamel tufts, but not as wispy)) .. and from further away, the enamel spindles look like icicles off of hte DEJ while the enael tufts look like little treets/ branches

Question 29

what cuases the formation of Hunter-Schreager bands (and what are these?)

Answer 29

Hunter Schraeger bands are isilbe as alternating light and dark bands of enamel– this visual is caused by the differnt direction of enamel rods (and the HA crystals in the rods)) in adjacent layers ((adj layers of rods oritents differently == looks like light-dark banding startiing from the DEJ) == helps with the strength of the enamel. IS importnat to consider during operative dentistry

Question 30

T/F ameloblasts are tall, columnar epithelial cells

Answer 30

True. Ameloblasts are tall, columnar, epithelial cells

Question 31

Where does the differnetiation of the inner enamel epithlial layer begin? -

Answer 31

The differntiation of the inner enamel epithelial layer begins in the coronal most kocation of hte inner enamel epi layer ((recall== the inner layer = the coast of the enamel organ bay))

Question 32

what is the most common meet-up scheme of enamel and cementum at the CEJ?

Answer 32

The most common meet-up scheme of the enamel w the cementum at the CEJ is that the cementum will overlap the enamel

Question 33

T/F an enamel pearl is considered an ectotopic enamel formation

Answer 33

True. an enamel pearl is considered an ectotopic enamel formation (unusual location of formation))

Question 34

High consumption of citrus/ acidic foods would lead to what type of tooth wear?
Abrasion,attrition, or erosion?

Answer 34

The consumption of highly acidic things would lead to the EROSION of teeth

Question 35

Holding a toothpick bt the teeth would lead to what type of tooth wear? Is this considered a normal type of wear?

Answer 35

Holding a toothpick will cause abrasion to the teeth. Abrasion is NOT a normal type of wear experienceed by teeth ((atrition, such as from the force of masticiation IS a nomral force)

Question 36

is enamel considered a connective tissue?

Answer 36

No! enamel is not a connecive tissue (further, contains no collagen like the other minerlaized tissues) ENAMEL = ECTODERM

Question 37

T/F enamel formation is continuous throughout life

Answer 37

False. Enamel formation is finite. The ameloblast finishes its job once the enamel formative cycle has reached the desired thickness of enamel. The process of reminerlaizationa nd demneralziation IS, however,throughout life

Question 38

T/F::
Enamel is avascular, aneural (no nerves), avascular (no blood supply), alymphatic, but still considered a chemincally ALIVE tissue

Answer 38

True. Enamel is acellular, avascualr, alymphatic, aneural.. and is considered an alive tissue

Question 39

Does dentin or enamel form first?

Answer 39

Dentin forms before enamel. Ameloblasts induce odontoblasts to form, then dentin in made, and after dentinthe enamel is made by the ameloblasts

Question 40

T/F Enamel tissue is a composite biological mineral wih apatite cytsals iriented in a complex 3D pattern

Answer 40

True. Enamel tissue is a compoisute biological mineral with apatite crystals oritented in a complex 3D pattern

Question 41

Is enamel able to withstand shearing and impact forces well?

Answer 41

Yes. Enamel is able to withstand shearing and impact forces well

Question 42

Does enamel need a wet or dry environment?

Answer 42

Enamel needs a WET environment (hence, caution during prolonged rubber damming/ tooth isolation as it could dry out the enamel and make it non-vital)!

Question 43

Amelogenin is an organic protein found in the organic substance of the enamel – what does it do?

Answer 43

Amelogenin is a protein (organic) found in the organic substance of enamel - it is unique to enamel and functions to promote normal mineralization – these enamel proteins are arranged in a lacelike pattern throughout the enamel. assc with mineralziation

Question 44

What are some of water’s functions in regards to enamel?

Answer 44

Water forms a hydration shell around the enamel rods (prevents drying. desiccation). the water also is a pathway for delivering fluride ions (that can incoproate into the hydroxyapatite crystals to form fluoroapatite which is even stronger)) , also water delivers calcium and phosphorus ions for remineralziation, as well as whitening substanes, etc //water enters the enamel via micropores