Oral Environment Flashcards
The hardest tissue is _____.
Enamel
Enamel covers the ______________
It contains no________ so enamel cannot ________.
Enamel covers the dentin in the crown of the tooth
It contains no living cells so enamel cannot repair itself from decay or wear
Dentin is ________ than enamel and contains _________ which can trigger ________ if exposed.
softer
tubules which can trigger sensitivity if exposed
Pulp is ________ at the ______ of teeth containing ______.
Soft tissue, center, nerves, blood vessels and connective tissue
Cementum is ___________ covering the ______ giving attachment to the ______.
Hard tissue, tooth root
PDL
What are the minerals found in teeth?
Calcium Phosphate
Ca2+ and PO₄³⁻
The phosphate in teeth is organic.
True or False
FALSE
INORGANIC PHOSPHATE ANIONS
Is calcium phosphate naturally occuring?
Yes
What is the specific calcium phosphate mineral found in our teeth?
Hydroxyapatite
Ca5(PO4)3-OH
What is the most mineralized tissue in the body?
What other characteristic does this give the tissue?
What is the composition?
Enamel; Hardest Tissue
96% - Inorganic Hydroxyapatite
2%- Organic enamelins for bonding
2%- Water
Enamel is ______ than bone.
Harder
Enamel minerals are composed into _________.
Hydroxyapetite rods that run 50% vertically and 20% in a cross pattern.
Enamel rods are _______ to the DEJ.
Perpendicular
Enamel is general is not ________. At the cusp tip, this feature is increased and creates _______ which are _______.
Straight
Gnarled enamel which is a twisted course of enamel rods
Why are enamel rods arranged the way they are?
Crack Propagation Resistance
Increases structural stability of enamel
Describe the Hardness Distribution of Enamel
Occlusal surface is the HARDEST and decreases as we approach the interior of the tooth
What is demineralization?
A _____ph often causes this.
Net loss of minerals because of ion exchange
VERY low!
H+ will bind phosphates and release calcium , hydroxyapatite breaks down due to acidity.
Demineralization occurs at pH ________.
Normal oral pH is ______.
4.5-5.5
6.8-7.4
Etch is made of _________ and functions to ______________.
35-40% of phosphoric acid
Create porosity in dentin and enamel so that bonding can occur more efficiently of products such as resin composite or certain crown cements.
What is the DEJ?
Is it mineralized?
The boundary between enamel and dentin that is highly mineralized.
Dentin-Enamel-Junction
The DEJ is a ____________. This means mechanical properties changes as _________, taking upon properties of ________.
Transitional tissue
we travel from enamel to dentin, taking upon properties of whatever it is closest to
Dentin is makes up the ________ portion of the tooth.
What is the composition?
It has ______ from ______ interior to _______.
Largest
50% inorganic hydroxyapatite
25% Organic Type I collagen
25% Water
Has tubules from pulp interior to enamel
There is a theory that the fluid in ________ can shake _________ and cause _________.
dentinal tubules can shake nerves to cause sensitivity
Dentinal tubule density increases from _________ to _________.
DEJ to pulp
Pulp is very concentrated; enamel not so much
Some tubules do not reach the enamel.
True or False?
True
Surrounding dentinal tubules is __________.
Filling the space between all the tubules is __________.
Peritubular Dentin
Intertubular Dentin
The most abundant protein in the human body and part of the ECM is __________. Its role is to _______.
Type I collagen
Glue of connecting tissues
Collagen is made from _______. It becomes ________ and then ________ which arrange into _______.
AA
Tropocollagen
Fibrils
Fibers
Hierarchy of Dentin
Collagen Fiber
Collagen Fibrils surrounding tubule as peritubular dentin
Intertubular Dentin
Total Dentin structure
Minerals are in the fibers or surrounding the tubules
Intertubular dentin is considered mineralized __________.
Collagen
Peritubular dentin is very highly ________.
mineralized
There is very little collagen and mostly hydroxyapatite
What is the Dentin Hydronamic Theory?
Dentin is porous
If we make an occlusal cut of dentin, we can see water from the tubules.
Dentin porosity is even across the tooth.
True or False
False
As we age, our dentin tubules __________.
Close up as minerals from intertubular dentin precipitate and fill up tubules.
What can influence Dentin properties?
Drilling: Creates a smear layer
Acid Etching : Exposure of tubules
What is a smear layer?
When drilling, particles generated will coat the surface of dentin and may infiltrate the tubules which can change the microstructure of tooth.
This is why we etch! To remove the smear layer
Enamel contains more _______ than dentin.
Hydroxyapatite
