Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
41 Cards in this Set
- Front
- Back
What is the Ameloblast Life Cycle
|
Morphogenic
Organizing Formative Maturative Protective Desmolytic |
|
Reversal of Polarity
|
Occurs during Organizing stage of Ameloblastic life
Basally located organelles move into apical position Central nucleus moves into basal position |
|
BMP
|
Released by mature ameloblasts
Stimulates dental papilla mesenchymal cell's MSX-1 gene Induces mesenchymal cells to become odontoblasts |
|
What is the first tissue that is produced during tooth formation?
|
Dentin
|
|
Dentinogingival Membrane
|
1st layer of enamel that gets laid down
|
|
Difference b/t enamel & dentin formation
|
odontoblasts have processes that get trapped in deposited dentin
ameloblast processes eventually break off from the cell Also, once enamel is done getting deposited, you wont get any more laid down |
|
Amelogenin
|
Enamel Proteins
rich in Proline Two types - TRAP (tyrosine rich) and LRAP (leucine rich) 1st protein that gets laid down in the organic matrix thixotropic properties |
|
What is the 1st protein that gets laid down in the organic matrix?
|
Amelogenin
|
|
thixotropic properties
|
Refers to Amelogenin
flows when HAP crystals get deposited and squeezes out the Amelogenin |
|
How do you get 96% HAP and virtually no proteins?
|
deposition of HAP crystals squeezes the amelogenin out of the way
|
|
Enamelin
|
Enamel Proteins
formed from a mixture of Amelogenin breakdown products + enzymes + serum albumin Enamel mineralization occurs right after matrix is laid down |
|
Primary Mineralization
|
accounts for the first 25-30% of the HAP crystal formation
|
|
Secondary Mineralization
|
rest of the mineralization that takes place, making the original HAP crystals larger
More specifically refers to what part of the enamel is getting mineralized |
|
Hypoplasia
|
defects in organic matrix formation
causes mis-shaped, small teeth Can be caused by genetic factors, systemic illness, or local trauma |
|
Hypomineralization
|
defects in the mineralization process
causes soft, unsupported teeth Can be caused by genetic factors, systemic illness, or local trauma |
|
AMEL gene
|
dominant on the X chromosome in females and Y chromosome in males
Used to determine the sex of dead victims using teeth |
|
Enamel makeup
|
96% inorganic + 2% organic + 2% water
|
|
Purpose of enamel
|
to protect the dentin underneath
|
|
Enamel Rods
|
basic functional unit of enamel
shape is polygonal / hexagonal in cross-section extend from the DEJ towards the free surface horizontal towards the cervical, more vertical towards the coronal & apical |
|
What is the basic functional unit of enamel
|
Enamel rods
|
|
Gnarled Enamel
|
enamel rods curl, bend, twist
Increases adhesion of layer Occurs mostly in areas like enamel tufts and near DEJ of cusps |
|
Keyhole Hypothesis
|
1 ameloblast contributes to the head
3 amelboblasts contribute to the tail each ameloblast will contribute to 4 different enamel rods |
|
How many enamel rods do each ameloblast contribute to?
|
4
|
|
Ten Cate’s interpretation of Enamel Rod Structure
|
The head is the entire rod
The tail part is the inter-rod substance 1 ameloblast contributes to a whole entire rod 3 ameloblasts contribute to the inter-rod substance |
|
How are HAP crystals arranged in the head region of enamel rods?
|
deposited parallel to e/o
|
|
How are the HAP crystals arranged in the tail region of the enamel rods?
|
deposited at an angle
|
|
Hunter Schreger Bands
|
Hypomineralized Structures
Dark & Light Bands only be seen w/ reflective light minimize the risk of cleavage when occlusal forces are applied also shock absorbers |
|
Lines of Retzius
|
Hypomineralized Structures
dark lines disturbance in the growth pattern the wider the band, the greater the disturbance most numerous in the cervical neck of the crown |
|
Perikymata
|
wherever Lines Retzius touch the tooth’s free surface
creates transverse grooves on the tooth surface most prominent & numerous in the cervical neck |
|
Neonatal Lines
|
marks the baby’s transition from pre-natal to post-natal
Due to drastic change in the environment & nutrition It is seen as a thickened Line of Retzius |
|
Daily Incremental Lines
|
represent shorter periods of growth disturbance
|
|
Structureless enamel
|
No rods
Seen near free surface of tooth as well as near DEJ Occurs at beginning and end of enamel ofrmation Found in 70% of permanent teeth, 30% of primary |
|
Lamellae
|
starts at the free surface of enamel
Extends down through enamel and may cross into dentin caused by disturbance in growth leaf-like or ribbon-like (branched) Hypomineralized susceptible to bacterial acid attack |
|
Tufts
|
starts at the DEJ
extends slightly into the enamel due to disturbances in growth does not pose as point of vulnerability |
|
Spindles
|
starts at the DEJ
rope-shaped (figure 8 in cross section) every spindle has an odontoblastic process Tissue cannot calcify properly around the odontoblatic process |
|
What is the shape of the DEJ in secondary dentition?
|
Scalloped
Increases surface area for the enamel to attach to the dentin |
|
What is the shape of the DEJ in primary teeth?
|
Straight DEJ
|
|
Why doesn't tissue in pits and grooves mineralize properly?
|
Ameloblasts die out in the grooves and fissures
|
|
What happens to enamel as you age
|
It gets thinner because it is not capable of regeneration
Therefore tooth gets narrower and shorter Enamel also gets darker Enamel permeability decreases as pores fill up |
|
What happens to the tooth as you age
|
It gets narrower and shorter because enamel gets thinner with age
|
|
How does the tooth try to compensate for the loss of contact with the opposing teeth
|
The crown tries to super erupt
|