Root Development and PEriodontium Flashcards
Anton van Leeuwenhoek’s addition to science
Simple microscope
Disoveded Animalcules
Enamel, dentin, bone (not cementum
Marcello Malpighi addition to science
Malpighian corpuscles
Pyramids of kidneys
Malpighian tubules in insects
Substantia tartarea on roots of teeth
when were compound light microscopes invented
early 1800s
what did Jan Purkinje discover
Purkinje cells and fibers
what did Anders Rwtzius find
Striae of Retzius by looking at dentin tubules
other name for outer substance
Cortical substansen
other name for bony cells
Osseous corpuscula
other name for bony substnace
substantia ossea
what did GReene Vardiman black do
Classification of caries
Amalgam preps
Foot powered drill
first detailed understanding of how cementum functions for periodontium
Recognized Sharpey’s fibers in cementum and bone unite the periodontal complex
Describe reparative cementum
what is the tooth root
Root dentin
associated root canals (pulp)
what is the support system for the tooth
Periodontium
what makes up the periodontium
Cementum
Alveolar bone
Periodontal ligament
Gingiva: tooth associated and gingival ligaments
what defines the edge of enamel organ during bell stage
The cervical loop
what kind of structure is the cervical loop
A crown strucutre
what defines the forming root
Hertwig’s epithelial root sheath
when does the Cervical loop turn into hertwig’s epithelial root sheath
Initiation of root development
what is Hertwig’s epithelial root sheath derived from
The cervical loop
what is HErtwig’s epithelial root sheath an exention from
Enamel organ
what is HErtwig’s epithelial root sheath made of
Bilayer strucuture of IEE and OEE
what does Hertwig’s epithelial root sheath do
Architect of the root defining size and shape and number of roots (morphogenesis)
Induces root odontoblast differentiation
How does HERS pdefine a single rooted tooth
Proliferates apically to define the root
How does HERS make multiple roots
Epithelial interradicular processes
what are Epithelial interradicular processes
Tongues of epithelium growing towards one another
what does HERS cell migration and proliferation determine
Size shape and number of roots
what does HERS do for root odontoblasts
Causes them to differentate via epithelial-mesenchymal signaling
what is the dental papilla made of
Undifferentiated ectomesenchymal cells
what does HERS do to Dental papilla cells
Induces them to differentiate to pre-odontoblasts then odontoblasts
how does Root dent form
In steps with HERS proliferation
What does HERS signal to the Dental papilla
Smad4 transcription factor
Sonic hedgehog secreted signal to papilla cells
what does HERS signalling to the dental papilla lead to
Induces Gli1 TF
Downstream Nfic TF
Odontoblast differentiation
what cannot be done without Nfic
Dental papilla cannot respond to HERS signaling and cells do not differentiate into odontoblasts
Rootless Teeth
what genetic disease causes Rootless teeth
Autsomal dominant Dentin Dysplasia type I (TF, SMOC2 and others)
what else might rootless teeth cuase
Short, poorly developed roots
Obliterated pulp chambers
Mobility, tooth loss
What are some developmental root defects
Rootless teeth
Dilaceration (deformity in shape and direction)
Taurodontism (large pulp chambers at expense of root/fucations)
what causes Developmental root defects
HERS growth and root dentin formation
DEvelopmental defects might do what to teeth
PRone to breakage, exfoliation, ankylosis, difficult extraction, ortho movement, other issues
What happens to the HERS over time
Disintegrates shortly after infucing root odontoblast differentiations
Some become epithelial rest of Malassez
how do Epithelial rests of Malassez appear
As clumps, strands, or networks of cells in the PDL
what surrounds the Epithelial rests of Malassez
Basement membrane
Where are Epithelial rests of Malassez found
Close to root
sometime several cell layers away
Function of Epithelial rests of Malassez
Can cause cysts
periodontal homeostasis or regeneration
but not sure
is root dentin continuous with crown dentin
they are continuous
how is dentinogenesis different in Root and crown
nearly the same, but interacts with IEE of HERS instead of enamel organ
Cell differentiation within the Root Dentin
Ectomesenchym, Dental Papilla, Pre-odontoblasts, Odontoblasts
types of dentin in the root
Mantle
Circumpulpal
predentin
Primary, secondary, tertiary
what deffines the types of Cementum
Presence/absence of cells within its matrix
Origin of collagen fibers of the matrix
what is another name for Primary cementum
Acelular cementum
Aceullar extrinsic fiber cementum
what is another name for secondary cementum
Cellular cementum
Cellular intrinsic fiber cementum
how much of the root is covered with Primary or secondary cementum
Primary: upper 2/3 of the root
Secondary: appilcal 1/3 of the root
What are the types of cemenetum
Major: primary acellular and secondary cellular cementum
additional types: Acellular afibrillar Cementum (AAC), cellular mixed stratified cementum
what is Cellular mixed stratified cementum
Mix of alternating acellular and cellular layers
are all types of Cementum separated completely
No, they overlap
what does Acellular cementum cover
the cervical 2/3 of root
what is the primary cementum
the first formed cementum ( Acellular)
cells of Acellular cementum
No cells
what does Cellular cementum cover
apical 1/3 of root
what is the secondary cementum
the second formed cementum (cellular cementum)
cells of Cellular CEmentum
Cementocytes
special function of cementum
Attachment
Protection
Adjusting
Sealing
attachment roll of cementum
important for strong periodontal structure cementing the tooth in the socket
what type of cementum does attachment
Acellular cementum primarily
how doe cementum protect
Protects roots from resorption and repairing resorption pits
what is the adjusting roll of cementum
adjusts tooth position
what type of cementum does the adjusting
Cellular
Sealing roll of cemntum
seals the dentin tubles (hydrodynamic theory of dental sensitivity and inhibits bacterial invasion)
composition og cementum
like bone and dentin
50% inorganic HA
35% organic
15% water
Organic components of cementum
Collagen type I(90%)
other collagen type III and VII
non collagenous proteins
glycosaminoglycans (10%)
How is cementum different from bone
Avascular
No innervation
No turnover (growth by apposition)
Origin of cementoblasts
Derived from dental follicle (ectomesenchym)
Function of Cementoblasts
Make acellular and cellular cementum
Product of cementoblasts
Collagens
ECM proteins
Enzymes for cementum mineralization
Fate of Cementoblasts
Remain in PDL close to cementum surface
Regulate slow cementum growth through life
direct cementum repair
origin of Cementocytes
Subset of cementoblasts
embedded in cellular cementum matrix (dental follicle, ectomesenchyme)
function of cementocytes
unknown
produces of cementocytes
less than cementoblasts
Features of cementocytes
Reside in lacuna
extend dendrites through canaliculi to communicate and receive nutrients
Fate of Cementocytes
Remain in lacunae for life
may die their
origin of Dental follicle
Ectomesenchymal
What is the dental follicle a precurosor for
CEmentoblasts
PDL fibroblasts
Osteoblasts
what happens right before Cementum forms
Root dentin exists
HERS disintegrates to expose the root dentin surface
what do Cementoblasts differentiate from
the dental follicle
what do the Cementoblasts secrete to initiate cementogenesis
Initial collagen fibers
what do the initial collagen fibers in cementum do
Intermingle with unmineralized dentin at the CDJ
what do the initial collagen fibers connect to
Intrinsic and not yet connected with the PDL (Doesn’t even exist yet)
what happens to the dentin once the cementum initial collagen fiber bundles intermingle with dentin collagen fibers
Dentin completes mineralization
hardness of the DCJ
less hard to serve as a cushion between cementum and dentin
how were the origin of cementoblasts and cementum found
60s-90s
Electron microscopy
Ultrastructural evidence
what makes up the Hertqigs epithelial root sheath
Inner enamel epithelium
Outer enamel epithelium
does the PDL exist during cementogenesis
No, the dental follicle consists of loose collagen fibers around the developning tooth
what do the Pre cementoblasts do the outer enamel epithelium
break through it do go the the Dnetin to eventually prenetrate into the dentin matrix
what do the cell processes of the PRe-cementoblasts contain
Microfilaments and ribosomes
how do Cementoblasts look
Hang out on the root surface
Well developed Golgi, rER
what happens to the IEE once cementoblasts form
remnants of IEE away from the root sruface
what do PDL fibroblasts produce
primary collagen fiber bundles of PDL space
what do the primary collagen fiber bundles of the PDL space do
stitched to first cementum intrinsic fibers
what are the extrinsic fibers
a continuation of the initial intrinsic fibers
what do the extrinsic fibers become
mineralized sharpey’s fibers within cementum
what is the major fiber group for acellular cementum
Extrinsic fibers
what is the density of extrinsic fibers in acellular cementum
high density
importance of extrinsic fibers to accellular cementum
critical to the function
where do sharpey’s fibers insert
insert into both acellular cemntum and alveolar bone
what are sharpey’s fibers
Mineralized collagen fiber bundles for a strong anchorage of tooth-PDL-bone
Roll of Cementoblasts in cementogenesis
PRomote HA deposition betweena nd within collagen fibers
what are Sharpeys fibers made of
Mineralized collagen fibers cont with PDL in cementum and alveolar bond
how does Mineralization of cementum occur(Directyion)
from the root sruface out towards the bone
what is the scaffold for Cementum mineralization
Fiber fringe at the cementum-PDL interface made of Collagen substrated (Type I and Others)
what do Cellular secretions of ECM (non collagen) proteins participate in
Mineral precipitation
where do cells direct mineralization
in and between collagen fibers by ECM proteins and enzymes
how are extrinsic collagen fibers mineralized
Progressive mineralization
what is the fiber before cementum initiation
Fiber fringe
what happens when the Fiber fringe becomes engulfed and mineralized
Sharpey’s fibers
how does Mineralization of the Acellular cementum do
Mineralizes slowly over time (abuot 3 micrometers a year)
Aceullar cementum thickness over tie
Becomes thicker over time
what do secondary cementoblasts produce
Cementum matrix rapidly (cementoid)
produce intrinsic collagen fiber deposited into the cellular cementum ECM
what teeth have little cellular cementum
Incisors and canines (little role in tooth attachment)
how is Cellular cementum adaptive
Maintains tooth in proper occlusal position by compensating for enamel attrition throughout life
where can cellular cementum repair cementum resporption
anywhere on the root
how does Cellular cementum look before mineralization
a clear unmineralized cementoid quivalent to predetin or osteoid
steps of Cellular cementum mineralization
Cementoblast secreete collagen and other proteins
Time lag
Matrix mineralized
what can lead to delayed Mineralization
Excess cementoid
what conditions affect cementoid similarly to the osteoid
Conditions that delay/inhibit mineralization
What is embedded in cellular cementum atrix
Cementocytes
what are cementocytes connected to
connected to one another and the surface (PDL)
what are Cementocytes equivalent to
Osteocytes in bone
what types of cementum grow slowly throughout life
Both acelular and cellular cementum
how does CEmentum grow
no remodeling/turnover
grows via appositional growth
appositional growth
addition to the existing layer
what indicates successive layers of cementum
Longitudinal lines/striations/appositional growth lines
does resporption of cementum occur
sometimes
Classical hypothesis for cementum original
Ectomesenchym
dental follicle
cementoblasts
Alternative hypothesis for cementum origin
Dental epithelium
HERS
epithelial-mesenchymal transformation to cementoblasts
what allows follicle cells (pre-cementoblasts) to access root surface
Fenestration of HERS
too little cementum
cementum aplasia
Hypoplasia
too much cementum
Hypercementosis, may lead to ankylosis
loss of cementum
External root resorption
Deriodontal diseases
what is Hypophosphatasia
A rare skeletal disease leading to High ppi
Acellular cementum aplasia or hypoplasia
what is mutated in Hypophosphatasia
mutations in ALPL gene for tissue nonspecific alkaline phosphatase (TNAP an TNSALP)
roll of TNAP
breaks down pyrophosphate an inhibitor of mineralization
what does Hypophosphatasia affect
`bone (skeletal and craniofacial
Dentin
enamel
Acellular cementum most dramatic in terms of severity and prevalencedefec
defective/absent cementum due to hypophophatasia leads to
loose teeth
premature loss of primary and secondary teeth as fully rooted HPP teeth
Excessive cementum growth
Hypercementosis
Cause of Hypercementosis
TRauma
Genetics
Idiopathic
symptoms of Hypercementosis
Generally asymptomatic
ankylosis
difficult in extraction
genetic hypercemetnosis is the opposite of what
HPP
protein for Acellular cemetnum
Bone sialoprotein (BSP)
where was Bone sialoprotein found
First discovered in bone but also in dentin and cementum
roll of bone sialoprotein
Promotes ha formation
acellular cementum formation in mice
knockout of Bone Sialoprotein leads to
Cementum hypoplasia
PDL detachment
Periodontal breakdown
human equivalent to Bone Sialoprotein knockout in mice
consistent with aspects of aggressive periodontitis
what does external root resporption
Odontoclasts (osteoclast like cells)
how common is root resportion
common to be mild in 1 or more teeth
Root resportion is caused by
Excessive orthodontic force (usually apical effect)
related to trauma, severe periodontitis, genetics
also idiopathic
Multiple idiopathic cervical root resporption
agressive as 19 teeth affected over 30 yeras
11 extracted/exfoliated
treating Multiple idiopathic cervical root resportion
effective treatment
what causes root surface caries
Bacteria/plaque
what is the Root (surface) caries
Exposed root surface
Soft, progressive lesion distinct from clastic resporption
when does Reparative cementum form
Following root cementum resorption by osteoclasts and odontoclasts
what does Reparative cementum form
Fills resporption pit (Howship’s lacuna)
what kind of CEmentum is reparative cementum
Cellular regardless of location
Concerns with Reparative cementum
How well is it bound to dnetin
is new cementum well attached to PDL
what does the alveolar process/bone form
the socket that holds the tooth
types of bone in the alveolar bone
cortical plates buccal and lingual Trabecular bone (spongiosa)
what part of the alveolar bone is invovled with periodontal function
alveolar plate
the alveolar bone lining the socket, inner aspect facing tooth root
Bundle bone or alveolar bone proper
what is included int he alveolar bone
Extrainsic collagen fiber bundles, mineralized sharpey’s fibers (similar to acellular cementum)
size of primary fiber entering bundle bone vs cementum
PRimary fibers are larger and less dense in bundle bone
what is the lamina fura
a radiopaque layer lining the socket of alveolar bone
why is lamina dura more radiopaque
from thick bone without trabeculation not increased mineral content
radiooapquiolucenticity of PDL
PDL is radiolucent
is the compact bone of the alveolar process entirely solid
Not entirely solid
performations of the compact bone of the alveolar processis for
Blood vessels and nerves to enter the PDL space
what is the cribiform plate
a strucuture pierced by many small holes
cells of the alveolar bone
Hematopoietic stem cells Monosyte/macrophage Osteoclast Extomesenchyme dental follicle/mesenchymal stem cells Pre-osteoblast Osteoblast lining cell osteocyte
what cells work in function to do bone remodelling
Osteoclasts and osteoblasts
the fastest remodling bone in the body
Normal remodeling of the alveolar bone
Normal bone resorption allows for what
Tooth eruption
Normal tooth resporptions occures when
When decidious teeth are exfoliated
when does abnoraml tooth resporption occure
when clasts resorb the roots of permanent teeth
roll of the alveolar bone
Distribute occlusal loads
existance of alveolar bone depends on what
the interaction with teeth
the mechanostate thtoery of bone loading
Bone loading cuases growth
bone unloading cuases loss
what happens to alveolar bone of edentualous mandible
gradually lost
Wolff’s law/ frosts mechanostate model of reponse to bone loading
bone loading cuases bone growth
Bone unloading cuases bone loss
what are periodontal ligaments
soft fibrous connective tissue between tooth and alveolar bone
ligament
fibrous connective tissue connecteing bone to bone
PEriodontal ligametn
Connects bone to tooth in a unique joint called a gomphosis or tooth socket
width of the periodontal ligament
.1-.4 mm but varius with person and healthy
Functions of pdl
Supportive Nutritive sensory Defensive maintenance/reparative adaptive
supportive function of the pdl
primary collagen fibers attach tooth to bone
nutritive function of the pdl
Blood supply to cells of the region, including cementoblasts and cemetocytes
sensory function of the PDL
innervated for sensing posotion and pain
defensive function of the PDL
delivers immune cells including macrophages and neutrophils
Maintenacne/reparative function of the PDL
contains stem and progenitor cells that can repair or regenerate pdl, bone, cementum
adaptive roll of PDL
based on mech loading, adpats fiber orientation and influences neighboring alveolar bone remodeling
how does the PDL arrange itself
to accept and distribute tensile forces from mastication
what happens to PDL after ortho movement
returns to the same width
components of the PDL
Ground substance
Collagen fibers
Oxtalan fibers
GRound subance of the PDL
amorphous background material of proteins, proteoglycans, and water
what types of collagen are in the PDL
I, III, XII
what does the Collagen fibers make up in the PDL
fiber bundles (spliced rope) 97% of fibers
oxytalan fibers
small elastic fibers, support collagen fibers and blood vessel walls
commonness of Oxytalan fibers
3%
elastic fibers in the pdl
None, PDL is more stiff for wistanding forces
organization of the PDL in pre-emergence stage
PDL collagen fibers disorganized parallel to tooth/root
what happens to the PDL in the pre-functional and functional stage
Increase org
More fibers perpendicular/oblique to root/bone
Cementum as attachment
Collagen fibers bundles spand from what to what in the PDL
from mature tooth to bone (except transseptal group is tooth to tooth
Function of the PDL principle fiber groups
Resist intrusive and extrusive forces, tipping, and lateral movements
groups of PDL principle fiber
transseptal Alveolar crest horizontal oblique apical Interradicular group
the main PDL group resisting occlusal loads (intrusive)
Oblique group
what PDL travesl from tooth to tooth
TRansspetal fibers
major cell of the PDL
Firboblasts (lots)
roll of Fibroblasts in the PDL
secrete and remodel matrix
what does the PDL fibroblasts associate with
Collagen fibers to act as mechanotransducers
Cells of the PDL
Fibroblasts Osteoblasts, osteoclasts Epithelial rests of Malassez Stem/progenitor cells Immune cells
Roll of Stem/progenitor cells of the PDL
Ability to differentiate and regenerate
what gives blood tothe PDL
Superior and interior alveolar arteries
the major route of blood flow to the PDL
PErforating vessels (alveolar or intra-alveolar)
what are the extra routes of blood flow to the PDL
Apical routes and gingival vessel routes
what way does Venous drainage occure
axial direction
were is gingival crevicular fluid found
Found in the sulcus/gingival margin
importance of gingival crevicular fluid
transudate from vasculature
Diagnostic value
forces of mastication
LArge forces across short distances via hard teeth
what controls the forces of amstication
peripheral feedback (stops toooth damage and supporting tissues)
proprioception
periodontal complex to provide sensory feedback on tooth psosition, bite force, presence of objects….
do all bites occur at the same force
NO depends on consistency
how sensitive is the dental sensation in periodontius
detect 1 grain of sand between teeth
tyeps of nerve endings in the PDL
Free ending, tree like
Ruffini ending (slow adpating, found in skin)
coiled endings
Encapsulated endings
most common ending in the PDL
Free endings, tree-like
where are free endings found in the PDL
founding along the length of the root
receptors of free endinds in te PDL
nociceptors and mechanorecetpors
where are Ruffini endings found
near apex
receptors of Ruffini endings
Mechanoreceptors
were are coiled endings found in the PDL
mid region of the PDL
function of coiled endins
Unknown
where are ENcapsulated endings found in the PDL
near the apex
function of encapsulated endins
Unknown
Nociceptors
sensory receptor for painful stimuli
what odd things may be found in the PDL space
ERM
Cementicle
Ankylosis
Cementicle
Ectopic cementum in PDL attached or unattached
Ankylosis
Cementum-bone fusion leading to a loss of PDL space
epithelium of the gingiva
Oral epithelium
sulcus epithelium
Junctional epithelail
where is junctional epithelium found
enamel and cementum
roll of junctioanl epithelium
Barrier to microbial invastion with a fast turnover
what is junctional epithelium made from
Leftover enamel organ/reduced enamel epithelium
what are gingival liagemnt goupds
not pdl, but collagen fiber bundles spaning from tooth/bone to gingiva connective tissue
where are gingival ligament groups found
in lamina propria (underlying connective tisssue) of the gingiva
function of the gingival ligament groups
Resist gingival displacement
tyesp of gingival ligament groups
Circular group
Dentogingival
Dentoperiosteal
Alveologingival
what causes periodontal disease
Infection via a perio pathogens (porphyromonas gingivalis)
what does PEriodontal disease lead to
Inflammation
loss of periodontal strucutres (cementum, PDL, alveolar bone)
Inflammation of periodontitis is caused be
Inflammatory cytokines
matrix metalloproteinases
Osteo/odontoclasts
how does one do periodontal regeneration
scaling
root planing
antibitoic therapy
Guided tissue regeneration
protein used in periodontal regeneration
Emdogain and other growth factors that rely on stem/progenitor cells
