Oral Histo Flashcards
Placed in the root canal
gutta-percha
as a general rule, teeth have ___ canal(s) (not true for all)
1
Max 1st molar has ____ roots and ___ canals. The roots are 2 on the ___ and 1 on the ____
3 roots 3 canals, 2 on B
The Scope of Endodontic treatment
Diagnosis Treat pain vital pulp therapy Regenerative procedures (trauma damaging root) Nonsurgical root canal treatment Retreatment of unsuccessful internal bleaching Endodontic surgery-last option after failed root canals Traumatic injuries
Vital pulp therapy
Pulp is still vital… place MTA ontop of exposed pulp; root will gain width and length
regenerative pulp therapy
pulp is necrotic; use apical barrier technique
The art of endodontics
consists of conducting technical procedures during root canal treatment
the science of endo
basic and clinical sciences related to bio and patho that guide the art of endo to diagnose and treat via EBD
apical foramen
terminal end of root canal
used to determine working length
apical foramen
if you obstruct the ____ severe pain will occur
apical foramen
remove material short of the apical foramen
bacteria and necrotic tissue will remain and the root canal will fail
Stages of tooth development
Bud, Cap, Bell
the tooth originates as a __________ (the dentinal lamina) on the surface of embryonic jaws
a band of epithelial cells
The bell shaped downgrowth is the _____ origin
enamel
development of the dental papilla
densely packed cells, derived from cells that migrated from neural crest cells
dental papilla comes from cells which migrate from the
neural crest cells
dental papilla comes from cells which migrate from the
neural crest cells
the differentiation of ____ from undifferentiated ectomesenchymal cells is intiated and controlled by the ectodermal cells of the ______ of the enamel organ
odontoblasts
inner dental epithelium
in the enamel organ, a(n) _______ differentiates first and ______ second,
ameloblast
odontoblast
______ dentin is deposited first, along the DEJ in a band about _____ wide
mantle
150um
only the newly formed band of dentinal matrix along the pulpal border is uncalcified…..Significance?
external root resorption and internal root resorption
_______ are the site of intitial dentin formation/deposition
cusp tips
what is the initial dentin called?
mantle dentin
what is the initial dentin called?
mantle dentin
mineralization proceeds by an increase in ________ of the dentin
mineral density
dentin development moves in which direction
vertically-forms incremental layers
using a _________ of odontoblast you can see the coronal area of the pulp organ including the capillaries
photomicrograph
the inner and outer enamel _______ cells of the enamel organ fuse to form the ______
epithelial cells
root sheath
After crown formation they form a double layer of cells termed the root sheath or ______
Hertwig’s Epithelial Root Sheath (HERS)
The root sheath originates at the point that ________
enamel deposits end
As the root sheath lengthens, it become the _____ of the root
architect? okay…
the ______ cells control the length, curvature, thickness and number of roots
inner root sheath cells
Root dentin is formed —> _______ –>…
cell layer break down
–> mesenchymal cells from the tooth follicle move between the epithelial rests to contact the root surface and differentiate into cementoblast to deposit on the surface
–> last is calcification into mature cementum
Root dentin is formed —> cell layer break down –> ______
mesenchymal cells from the tooth follicle move between the epithelial rests to contact the root surface and differentiate into cementoblast to deposit on the surface –> calcification into mature cementum
lateral canals (define)
channels of communication between pulp and PDL
Cause of lateral canal formation
fragmentation of a localized area of a root sheath before dentin formation
Result of lateral canals (function)
direct communication between the pulp and PDL
Location of lateral canals
anywhere specifically apical region and furcal area
Significance of lateral canals
pathways along which disease may extend in either direction
size and shape of pulp chamber and age
become asymmetrical and smaller, decrease in height and size overtime
what can happen to the pulp overtime
calcification due to chronic irritation or trauma
significance of a changing pulp
can lead to difficulties in locating, cleaning, and shaping the root canal space
Root maturation
young, developed teeth have a better prognosis for pulp survival than teeth with mature roots after trauma
Number of canals/roots
at least one canal must be present in each root, some roots have multiple canals of varying sizes and configurations
Number of canals of MB root on max 1st molar
90% of the time this root has two canals?
size and location of the apical foramen-clinical importance
effects of cementum deposition or resorption
locating the apical constriction
establishing the working length by radiographs and apex locators
induction
initiation and development of dentin, when dentin is formed it leads to the formation of enamel
formation-pulp function (explain)
odontoblasts form dentin
Pulp functions (4)
responsible for formation of dentin, enamel, and the root
Also nutrition (pulp supplies nutrients for each of these formations and maintains the integrity
Defense: forming dentin in response to trauma or caries. Initiates immune response to foreign substances
Sensation: nerves in the pulp respond to stimuli….
Fast and sharp pain is the result of stimulation of the _______
myelinated sensory nerves while slow dull pain are unmyleinated nerve fibers
Direct innervation theory-based on what belief? Proven?
based on the belief that the nerves extend to the DEJ- however studies do not show nerves present at DEJ
most accepted theory for dentin hypersensitivity
hydrodynamic hypothesis
Transduction theory says what
the odontoblastic process is the receptor and that it conducts the pain in nerve endings in the peripheral pulp and in the dentinal tubules
Hydrodynamic theory
stimuli cause fluid flow through the dentinal tubules
This disturbance will lead to the activation of nociceptors in the inner dentin and peripheral pulp
Pulp sensation through the dentin and enamel is usually _____and ____ and is transmitted by _____ fibers
fast and sharp
ADelta fibers-narrow myelinated fibers
C fibers
slow conducting, dull, throbbing pain
fibers which dominate during inflammation and pulpal pain is dull
C fibers
The ___ has a much greater large fiber innervation than does the _____
PDL
Pulp
-many of these are mechanosensative which explains why pain from the tooth is more easily localized when inflammation has spread into the supporting tissues
what explains why pain from the tooth is more easily localized when inflammation has spread into the supporting tissues
The periodontal ligament (PDL) has a much greater large-fiber innervation than does the pulp, and many of these fibers are mechanosensitive
endo is the discipline of dentistry that deals with…
morphology, physiology, and patho of human dental pulp and periapical tissues, + prevention and treatment of diseases/injuries to these tissues
The ______ is the loose connective tissue in the center of the tooth.
dental pulp
The primary function of the pulp is to ____ and ____t he dentin that surrounds it and forms the bulk of the tooth
form and support
from where is differentiation of the odontoblast controlled
***inner enamel epithelium
when does the dental papilla become the dental pulp
**late bell stage-before this there is no dentin
what is the first thin layer of dentin that is formed
**mantle dentin
predentin makeup
90% collagenous fiber-comes before the mantle
which tissue surrounds the embryonic pulp in the “cap” stage of tooth development?
***dental follicle
derived from dental follicle
done and PDL?
What characterizes dental papilla
densely packed cells
what is the cause of discoloration in a grey looking tooth
***trauma
How to fix a tooth suffering from trauma discoloration
***internal bleaching
canal that runs horizontally
***lateral canal
what is the cause of lateral canal formation? Fragmentation before or after
***fragmentation before dentin formation
when the restoration does not go all the way down to the apical foramen
short filling-will likely need to redo
what does external resorption look like?
**osteoclast first target the cementum..so from the outside
endo defined
a discipline of dentistry that deals with the morphology, physiology, and pathology of the human dental pulp and periapical tissues, as well as the prevention and treatment of diseases and injuries related to these tissues
Keys: morphology, physiology, and pathology. and prevention and treatment
the loose CT in the center of the tooth
dental pulp
the primary function of the pulp is to
form and support the dentin that surrounds it and forms the bulk of the tooth
the bell shaped downgrowth is the enamel origin and is ________ in origin
ectodermal
responsible for amelogenesis
the bell-shaped downgrowth
the tissue within the invagination known as the _____ becomes the dental pulp
dental papilla
In the earliest stages of tooth development the dental lamina invaginates from the ____ _____
oral epithelium
In the earliest stage of tooth development during the Bud stage of tooth development, _______ is beginning to condense around the tooth germ.
Ectomesenchyme (EM)
During the earliest stages of tooth development… during the cap stage the condensed ectomesenchyme within the invagination is the _____ and the _______ is beginning to develop around the tooth germ
dental papilla
the dental follicle surrounds
In the ______ stage the odontoblast layer and blood vessels are visible in the dental pulp
early bell stage
the dental papilla is derived from cells that have migrated from the _________ (__________) and mingled with cells of local mesenchymal origin
neural crest (ectomesenchymal cells)
the ______ is significant in supporting enamel organ bud formation into the cap and bell stage
dental papilla
blood vessels and sympathetic nerve fibers appear early in the central region in the development of the _________
dental papilla
During development of the dental papilla cellular changes result in formation of ________ around the central papilla
mineralized tissue
The papilla becomes known as the ______
dental pulp-when?
Controls the differentiation of odontoblasts from undifferentiated ectomesenchymal cells is initiated and controlled by the __________ of the ________ of the enamel organ
ectodermal cells of the
inner dental epithelium
ameloblasts function (more than just enamel production)
Synthesize growth factors and signaling molecules that pass into the basal lamina of the epithelium and from there to the predontoblast.
The cells beneath the forming odontoblasts remain undifferentiated stem cells and retain the potential to differentiate…. note that once they differentiate they will lay down dentin through another process.
How dentin is layed down? Start with ameloblast (long answer)
ameloblast make GF and signaling molecules –> into basal lamina to the preodontoblast –> differentiate into odontoblast –> inner dental epithelium that had the signaling molecules dissapears –> odontoblast link via tight junctions and gap junctions begin to lay down dentin
once odontoblasts differentiate, they link up, how?
Via tight junctions and gap junctions
Cells which respond to a signal from the odontoblasts and begin to deposit enamel
cells of the inner dental epithelium
epithelial mesenchymal interaction
the back and forth signaling between cells of the inner dental epithelium and dentin being layed down
Cells of the inner dental epithelium respond to signals from the _____ once dentin formation has begun and they then begin to deposit ______
signals from the odontoblasts cause the cells of the inner dental epithelium to deposit enamel
At which stage has the internal dental epithelium differentiated into a layer of ameloblast but not laid down enamel
at the late cap stage
During the late cap stage, has the outer layer of dental papilla differentiated into odontoblasts?
No
Where outer cells of the dental papilla begin to become odontoblasts
at the periphery of what is now the dental pulp
During the cap stage what are the ameloblasts doing
They fully differentiate but will not lay down enamel yet
In what stage are odontoblasts laying down dentin and ameloblasts lay down little, if any enamel
bell stage
Describe dentinogenesis (appearance of odontoblast)
odontoblast elongation and gaining the appearance of the protein producing cell
When and where does a process develop which will become known as the odontoblast process
during dentinogenesis and this process develops at the proximal end of the cell adjacent to the ADJ
A process develops at the proximal end of the cell adjacent to the ADJ during which stage?
Dentinogenesis
Gradually the cell (odontoblast) moves in what direction?
Pulpward
how dentin is formed along the ADJ
in increments
The first material deposited by odontoblasts during dentinogenesis? Describe it too
First deposited is the dentin matrix (pre-dentin) which is a meshwork of collagen fibers and becomes calcified within 24 hours
Pre-dentin becomes calcified within…?
24 hours
Two phases of dentinogenesis
first: collagen matrix formation
Second: deposition of Ca phosphate (hydroxyappatite) crystals in the matrix which grow, spread, and coalesce until the matrix is completely calcified
In the enamel organ is an ameloblast or odontoblast first to differentiate?
So is dentin or enamel formed first?
The ameloblast differentiates first BUT the odontoblast will actually form the dentin before the ameloblast forms enamel.
First dentin formed and where?
Mantle dentin along the DEJ
Width of the mantle dentin first formed
about 150um wide
Where is predentin found? what is it?
it borders the pulp and is newly formed dentin before calcification and maturation
Predentin composition
90% type 1 collagen fibers and 10% noncollagenous proteins which calcify within 24 hours as the odontoblast deposit a new band of collagen fibers
What is the significance of the fact that only the newly formed band of dentinal matrix along the pulpal border is uncalcified
The external root and resorption of the internal root?
Key is that areas that do not calcify cannot be bound by osteoclasts
What protects the external root surface from external resorption
precementum
inner root sheath cells
The inner root sheath cells control the length, curvature, thickness and
number of roots
Apical foramen defined
the portal of exit of pulp tissue into the peridontium
Apical foramen location
at the end of or a short distance coronal to the anatomic root
Number of apical foramen per tooth
One or multiple
Pulp horns extend from what to what
the chamber into the cuspal region
In young teeth, pulp horns are
extensive and may be inadvertently exposed during routine cavity prep
Primary function of dental pulp (2)
Form and support the dentin
_____ is the loose CT center of the tooth
Dental pulp
Origin of the bell shaped downgrowth (which is the enamel organ)
Ectodermal –> responsible for amelogenesis
Responsible for amelogenesis
The enamel organ, which is the bell shaped downgrowth
The tissue within the invagination (the dental papilla) becomes the
Dental pulp-during the CAP stage
During the earliest stages, the dental lamina invaginates from what
the oral epithelium
During which stage is the Ectomesenchyme beginning to condense around the tooth germ?
Bud Stage
During which stage does the dental follicle form around the tooth germ?
Development begins during the Cap Stage
During which stage are the odontoblast layer and blood vessels visible in the dental pulp
The early bell stage
the dental papilla is derived from cells which migrated from where
the neural crest (ectomesenchymal cells)
The dental papilla is referred to as what? (think what cells are here)
Fibroblast in a delicate reticulum
Blood vessels and sympathetic nerve fibers appear early in what region
the central region
During development of the dental papilla, cellular changes result in the formation of what around the central papilla?
Mineralized tissue
The papilla becomes known as what
the Dental pulp
What controls, and initiates the differentiation of odontoblast from undifferentiated ectomesenchymal cells
The inner dental epithelium of the enamel organ
What synthesizes growth factors and signaling molecules that pass into the basal lamina of the epithelium
Ameloblast
Ameloblast produce GF and signaling molecules, where do these go?
They pass into the basal lamina of the epithelium and from there to the preodontoblast
When does the initial dental epithelium which contained the signaling molecules disappear? What happens next?
Once the odontoblast layer has differentiated… and now the odontoblasts begin to lay down dentin
Odontoblast are linked by what (3) just before laying down dentin
tight junctions, desmosomal junctions, and gap junctions
Once dentin formation has begun, the cells of the inner dental epithelium begin responding to a signal from what and what does this initiate?
They begin responding to a signal from the odontoblasts to begin depositing enamel
Epithelial-mesenchymal interaction
Once dentin formation has begun, the cells of the inner dental epithelium begin responding to a signal from what and what does this initiate….
They begin responding to a signal from the odontoblasts to begin depositing enamel
this is an example.
Young, partially developed teeth have a ______ prognosis for a pulp survival than teeth with mature roots after trauma
better
