oral histology compendium
TRANSCRIPT
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ORAL TISSUE AGING: processes
More stuff e.g. fibrosis & fat tissue
Less stuff e.g. wear of enamel
Misplaced e.g. gingival recession
Bad stuff e.g. collagen stiffer & lessdigestible; DNA mutated
Imbalance e.g. OSTEOCLASTS:osteoblasts
Compensation e.g. apical cementum
WABeresford
AGING ENAMEL
P
ULP
ATTRITION/ WEAR
More translucent = darker
MORE BRITTLE
reduced permeability
More resistant to caries?Changes in ion composition
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PULP
AGING in DENTINE
CIRCUMPULPAL DENTINE - mainmass of dentine
SECONDARY DENTINE -slow increment to pulpal surface
{
REPARATIVE DENTINE -
response to caries/erosion
DEAD TRACT -wide, empty dentinal tubules
SCLEROTIC DENTINE -tubules narow, thenbecome filled with mineral
Diffuse
calcification
AGING PULP
PULP HORNobliterated
30 dentinedeposition
makes CHAMBER
SMALLERCELLS -Odontoblasts
FibroblastsMacrophagesMast cellsLeukocytes
Blood vesselsNervesLymphatics
Denticles
MATRIXCollagen I fibers
Collagen III fibers
ROOT CANALnarrows
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CEMENTOCYTES
PULP
AGING CEMENTUM
HYPERCEMENTOSIS -
excess deposition
CEMENTOCLASIA - erodedcementum
Interstitial AreaAGING PDLBone surface
more irregular
Bundles
less distinct
PDL Width
DENTINE
PULP
BONE
P
D
L
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AGING GINGIVA
Epithelialattachmentlooser,
displaced
DRY - Xerostomia -Dry mouth
INFLAMED
HyperkeratosisTOOTH
PERIODONTITIS
Periodontalligament
TOOTH
Alveolar bone
GINGIVA
EPITHELIAL ATTACHMENT-unstable, loosens &migrates down, & allowsbacteria into
CONNECTIVE TISSUE
resulting in chronicinfection &
inflammation &
systemic spread ofbacteria &
loss of teeth
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causes loss of alveolar ridges Mx & Mb
EDENTULOUS MANDIBLE
illustrates dependence of bone on use
loss of teeth
& loss of facial height
However, mandibularbody is less affectedby aging osteoporosis
than spine & longbones
BONE RESPONSE TO
TOOTH DISUSE Alveolar SPONGIOSA mostaffected, with extensiveloss of trabeculae
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LIPRED MARGINVERMILION BORDER
HAIRY SKINloseselasticity
MUSCLE
LABIAL MUCOSA
thick strat squam ep thins
LABIALGLANDmucous
Fordyces spots - sebaceousglands - more visible
Tongue papillae
smoother
Sub-lingual bloodvessels engorge- Caviar tongue
AGING TONGUE
Lingual gland
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CHEEK
SKIN
BUCCAL MUCOSAthick strat squam ep thins
BUCCAL GLANDmucous
MUSCLE
ADIPOSE TISSUE
Mucosa
loses elasticity
Fordyces spots - sebaceousglands - more visible & #
CHEEK
MINOR SALIVARY GLANDSMUSCLE
Smaller & fewer
Replaced by fibrous tissue
= STROMA:parenchymaMore lymphocytes present
Oncocytes develop
parenchyma= acini, tubules & ducts, i.e., epithelial components of gland
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AGING PAROTID GLAND
SEROUS ACINi
INTRA LOBULARDUCT
INTERCALATED DUCT
INTER LOBULAR DUCT
FAT
less control of
secretion quality
STROMA:parenchyma
ONCOCYTIC CONVERSION
As cuboidal epithelia and glands age, a few oftheir epithelial cells lose most of their normalorganelles and fill up with mitochondria.Mitochondria-rich cells are eosinophilic.
This event results in twoclasses of cell:
those that are functioning normallyand needmany mitochondria - gastric parietal cells, renalproximal-tubular cells, striated-duct cells, etc; &
non-functional mitochondria-stuffed cells in olderglands. These have acquired two names: theusual - oncocyte, and, as an exception, the archaicoxyphilcell in the parathyroids. & Hurthle cells
in thyroid
:
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ORAL TISSUE AGING: Interactions with
Altered & aging immunity
Microbial flora & disease
Changes of diet & food preference
deficiencies, malabsorptions
Altered dentition & prostheses
Aging nervous & endocrine systems
Trauma & repair
Mutated & moved DNA - tumorse.g., squamous carcinoma, adenocarcinoma, oncocytoma
Medicines & therapy
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ALVEOLAR BONE: Roles
The bone holds the tooth firmly in position tomasticate and, for the lower jaw, transmitsthe muscle-powered movements of the body
of the mandible. It also:
adapts the strengthand orientation ofattachment to varying load
helps to move the teethfor better occlusion
supplies vessels for the PDL & cementum
houses & protects developing permanentteethwhile suppporting primary teeth
organizes successive eruptionsof primary &secondary teeth
TOOTH TISSUES: Sources
DENTAL LAMINA
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
DENTAL ORGAN
ALVEOLAR BONE
TOOTH
PULP
DENTINE
ENAMEL
CEMENTUM
PDL
SUPPORTING
BONE
LAMINA DURA
Plate
Spongy bone
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Deciduous tooth
Gingiva
Cortical platedense bone
BODY ofMANDIBLE
ALVEOLAR BONE
in general
PDL
Permanenttooth
MANDIBULAR CENTRALINCISORS at 2 y
CORTICAL PLATE
ALVEOLAR BONEspecifically
ALVEOLAR BONE TERMS
SPONGIOSA
ALVEOLAR BONE isalso termed Lamina durafrom its X-ray densit, orcribriform bonefrom themany holes for vesselsto reach the PDL
Alveolar crest
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PDL Vessels DENTINE
Enter via cribriform(sieve) walls of thealveolus & at thebase
Lymphatic drainage
PULP
PDL
SUPPORTING
BONE
LAMINA DURA
Plate
Spongy bone
ALVEOLAR BONE
ALVEOLAR BONE TERMS
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PDL fibers (extrinsic)become imbedded innewly formed bone
BONE MATRIX
Fine collagen fibrils - intrinsic
MATRIXPROPORTIONS
collagen fibrils andglycoproteins &
proteoglycans 35%
Organic
mineral crystals 65%Inorganic
Imbedded PDL fibers -Sharpeys fibers
Osteocyte
MATRIX
OSTEOCYTE PROCESS
LACUNA (hole) for
CANALICULUS(tiny channel) for
Gap junction contactwith next osteocyte
OSTEOCYTE BODY
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TOOTH
BONE DEVELOPMENT
TOOTH BUD
DENTAL LAMINA from which DENTAL ORGANS (tooth germs) form
BRAIN
TONGUE
MAXILLARYBONE
MANDIBULARBONE
TONGUE
X
X
X
X
X
X
Mandibular bone
NASAL CONCHAE
FACIAL REINFORCEMENT
SEPTAL CARTILAGE
Maxillary bone
TOOTH BUD
HARD PALATE
X Skeletal muscle starting
XX
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TOOTH PRIMORDIUM/GERM
DENTAL LAMINA
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
DENTAL ORGAN
MESENCHYME
ALVEOLAR BONE
Mesenchyme
Condensations arewidely dispersedand separated tocommit a territoryto becoming bone
Continued division
& recruitment toosteoblast numbers
Vessels present
INTRAMEMBRANOUS OSTEOGENESIS
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OSTEOID
INTRAMEMBRANOUS OSTEOGENESIS
ACTIVE OSTEOBLASTS
OSTEOCLAST
TRABECULA
Mesenchyme
LESSACTIVECELLS
IM & EC OSTEOGENESIS
TRABECULAEthicken by division &recruitment of more
osteoblasts toincrease bone density
Mesenchyme later turnsinto marrow
Vessels : incorporatedfrom the start &remodel with the bone
OSTEOCLASTSactive from the start toremodel & reshape the
bone
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vessels
Osteoclast
Ca 2+
Active Osteoblasts
Bone canal
Resting cells
BONE CELLS
Periosteum
Osteocyte
Bone matrix = collagen fibrils +mineral crystals
Osteoclasts as a team eating out a resorption tunnel
Osteon/Haversian system withconcentric lamellar/layered bone
New bone -start of newosteon
Osteoblasts filling
in the tunnel
DENSE BONEREMODELING
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DENSE BONE
REMODELING*
Osteoclast
Ruffled border agitatingreleased enzymes & acid
Eaten-out hole is a
Howships lacuna
Un-mineralized OSTEOID betweenactive osteoblasts & calcified bone
DENSE BONE
REMODELING
Osteoclasts as a team eatingout a resorption tunnel
Osteoblasts filling
in the tunnel New bone
Sealing ringof tightattachmentto bone
JAW & TOOTH DEVELOPMENT early arch
BONE startingLINGUAL PLATE
BONE startingBUCCAL PLATE
SYMPHYSEALCARTILAGE
10 TOOTH GERM
20 SuccessionalTOOTH GERM
DENTAL LAMINA
WALLS OF BONYTROUGH OFDEVELOPINGMANDIBLE
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JAW & TOOTH DEVELOPMENT processes
BONE
10 TOOTH GERM
20 Successional TOOTH GERMon lingual side of 10
DENTAL LAMINA will grow back to formgerms for 3 permanent molars (5th e m)
PLANTING POTATOES
Bone creates thetrench; tooth budsare the spuds
JAW & TOOTH DEVELOPMENT processes
BONE startingLINGUAL PLATE
BONE startingBUCCAL PLATEgrows up morethan lingual
SYMPHYSEAL CARTILAGEwill be replaced by bone
10 TOOTH GERM
20 Successional TOOTH GERMon lingualside of 10
DENTAL LAMINA will grow back to formgerms for 3 permanent molars (5th e m)
Bony wall grows around& encloses 20 TOOTHGERM in a crypt
Interdental septumgrows across troughto separate teeth
Interradicular septumgrows between rootsof multirooted teeth
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TOOTH & MANDIBLE DEVELOPMENT
10 TOOTH
20 TOOTH GERM
MECKELSCARTILAGE
TONGUE
ALVEOLARBONE
DENTAL SAC
ALVEOLARNERVE
Oral ectoderm
Bone added tobase of alveolusfor tooth eruption
10 TOOTH
20 TOOTHGERM
MECKELSCARTILAGE
Alveolar crestgrows up
regresses & notused to formmandible
Bony plate grows upto enclose 2nd toothgerm in a CRYPT
Bone grows overalveolar nerve &vessels
Alveolus becomesdistinct from BODY
DENTAL SAC contributesalso to alveolar bone
MANDIBLE DEVELOPMENT
Remodeling will bring erupting1o tooth over developing 2o
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10 TOOTH
20 TOOTH GERM
MECKELS
CARTILAGE
TONGUE
ALVEOLAR
BONE
DENTAL SAC
ALVEOLAR
NERVE
Higher alveolar bone- i.e. deeper socket
Denser alveolar bone & morebody-alveolus distinction
Meckels cartilage gone
TOOTH & MANDIBLE DEVELOPMENT - Next
Remodeling brings erupting 1o
tooth over developing 2o
BUNDLE BONE
Imbedded ends ofPDL fibers createBUNDLE BONE
DENTINE
PULP
Imbedded PDL fibersare Sharpeys fibers
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TOOTH MOVEMENT
Osteoblastslaying downbundle bone
Tooth drifts mesially
by combined actions
of osteoclasts &osteoblasts movingbone, taking toothwith it
Osteoclastsresorbing bone
Plus PDLreorganization
Osteoclasts
resorbing bone
PDL fibersincorporated in boneas Sharpeys fibers
FUNCTIONAL ERUPTION& TOOTH MOVEMENT
Osteoblasts
laying downbundle bone
Cellular cementum added to apexCompensates for occlusal wear?
Occlusal wear
Bonyinterdentalseptum
Basil
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TOOTH MOVEMENTS
DRIFTING e.g., mesially, laterally
AXIAL - in long axis of the tooth
Basil
Occurring in eruption & use
ROTATORY
TILTING
By root growth &bone remodelling
By bone remodelling &PDL reorganization
Combinations of these fourmovements frequently occur
TOOTH MOVEMENT 2
Basil
Earlier boneposition
TILTINGTooth tilts by combinedactions of both osteoclasts& osteoblasts on bone of
each sideof socket
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TOOTH MOVEMENT
Tooth drifts mesially bycombined actions ofosteoclasts & osteoblastsmoving bone, taking toothwith it
Basil
Earlier boneposition
10/Deciduous tooth Close to EXFOLIATIONof Deciduous/10 Tooth
Bone trabeculaeadded by layers atbase of alveolus
Odontoclasts haveresorbed most ofdeciduous root
Bone remodellling
has brought 20 toothunder 10
20 tooth would beLARGER than shown
20 tooth
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STARTING EXFOLIATION of DECIDUOUS MOLAR I
ALVEOLARBONE
DENTINE
ENAMEL
Permanent Tooth underdeciduous molar, &between its roots
Inter-radicular septum of bone alsohouses 2nd tooth germ & is its crypt
Root resorptionby osteoclasts
PDL
PULP
EXFOLIATION of DECIDUOUS MOLAR III
Erosion of bone and the deciduous root is not steady & continuous,but may cease briefly, when some repair of eroded cementum &dentine can occur (by cementum).
Bone remodelling also goes on, and the alveolus andcrypt are changing all the time - repeated all along the jaw
DENTINE
ENAMEL
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2 Much surfacearea for attack byosteoclasts
1 Struts are thin tostart with ~ weak
3 Gap in a strut/trabecula cut right through isusually too wide to be bridged by any new bone
SPONGY BONE at more risk than dense bone
Reduction in # &size of principal
fibers
Periodontal reactions to disuseLoss ofalveolar bone
Bundledefinitionlost
PDLnarrower allaround
DENTINE
PULP
BONE
CEMENTUMthickensP
D
LCEMENTUMlosesSharpeysfibers
Mild bonedepositionon wall
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BONE RESPONSE TO
TOOTH DISUSE
SPONGIOSAmost affected,with extensiveloss oftrabeculae
ALVEOLAR BONE: Roles
The bone holds the tooth firmly in position tomasticate and, for the lower jaw, transmitsthe muscle-powered movements of the bodyof the mandible. It also:
adapts the strengthand orientation ofattachment to varying load
helps to move the teethfor better occlusion
supplies vessels for the PDL & cementum
houses & protects developing permanentteethwhile suppporting primary teeth
organizes successive eruptionsof primary &secondary teeth
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TOOTH TISSUES: CEMENTUM
ALVEOLAR BONE
WABeresford
PULP
DENTINE
ENAMEL
CEMENTUM
PERIODONTAL
LIGAMENT/ PDL
GINGIVA
Blade Shaft Grip
ENAMELCEMENTUMDENTINE
TOOTH DESIGN: Spear me
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TOOTH DESIGN: Spear me
ENAMEL CEMENTUMDENTINE
Shaft is hollow forPULP
Hand represented byPERIODONTAL LIGAMENT& ALVEOLAR BONE
Refinements
Closer to true proportions
CEMENTUM: Role
Cementum is the hard covering of theroot that can:
fuseto dentine, but
be aliveand
grow outwardsto trap the periodontal-ligament fibers, and thus
attachthe tooth to the alveolar bone.
It is itself a kind of bone, but is lesssusceptible to erosion
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vessels
Osteoclast
Ca2+
Active Osteoblasts
Bone canal
Resting cells
REMINDER -BONE CELLS
Periosteum
Osteocyte
Bone matrix = collagen fibrils +
mineral crystals
CEMENTUM-BONE DIFFERENCES
NO VESSELS OR CANALS
WITHIN CEMENTUM
FORMING CELLS ARECEMENTOBLASTS
NO TRABECULAENO MARROW
IMBEDDED CELLS ARECEMENTOCYTES
COLLAGEN FIBERSPERPENDICULAR TOSURFACE
vessels
Osteoclast
Ca2+
Active Osteoblasts
Bone canal
Resting cells
Periosteum
Osteocyte
Bone matrix = collagen fibrils +
mineral crystals
NO PERIOSTEUM
ACELLULAR CEMENTUMEXISTS
ALMOST NO REMODELING
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BONE-CEMENTUM SIMILARITIES
MATRIX MATERIALS
EROSION BYOSTEOCLASTS(cementoclasts)
APPOSITIONAL GROWTHFROM SURFACE
LACUNAE WITHCANALICULI FOR CELLS &CELL PROCESSES
INCREMENTAL GROWTHLINES IN MATRIX
SIMILAR APPEARANCE INSTAINED & GROUNDSECTIONS
vessels
Bone canal
Periosteum
Bone matrix = collagen fibrils +
mineral crystals
P
ULPAL
ORIENTATION: Terms
CUSPAL/OCCLUSAL
APICAL
CERVICAL {
CORONAL
RADICULAR
Enamel
Cementum
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PULP
DENTINE
CEMENTUM
CEMENTUM: Position
ENAMEL
CROWN
Cervix
ROOT
}
}Cementum is on the root, but can extend slightlyonto enamel. Cementum also can be exposed tothe oral cavity, if the gingiva recedes too far
CEMENTUM: types & width
The left of this Fig is
misleading in
suggesting that allcementum iscellular.
The cervical half isthin and acellular-no cementocytes
P
ULPAL
APICAL
}Cementum
10 mthick
700 mthick
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Multi-rooted teeth usually
have particularly thick &cellular cementumbetween the roots in aninter-radicularposition
INTER-RADICULAR CEMENTUM
CEMENTUM: Boundaries
Cemento-enamel junction CEJ
Dentino-cemental junction DCJ
Ligamento-cemental junction
APICAL FORAMEN
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E E
D D
E
D
CEMENTUM: CEJ VARIATIONS
OVERLAP C/Emost frequent
GAPdentine exposed
BUTT JOINTend-to-end
CEMENTUM
E
D
E
D
Reactivated cementoblastslay down cementoid
E
D
E
D
GROWTH OF CEMENTUM = PDL anchoring
Cementoid becomesanother layer of cementum.Cells make more cementoid
PDL
fibers
PDL fibers becomeimbedded in newlyformed cementum -
Sharpeys fibers
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Further down the rootcementoblasts proliferatedso that one cell canbecome imbedded as acementocyte, whileanother remains on thesurface as a cementoblastD
GROWTH OF CEMENTUM III
D
Further down the rootcementoblasts proliferate
PDL fibers omitted.
PDL fibers (extrinsic)become imbedded innewly formed cementum-
CEMENTUM MATRIX
Fine collagen fibrils - intrinsic
MATRIX
PROPORTIONS
collagen fibrils andglycoproteins &
proteoglycans 35%Organic
mineral crystals 65%Inorganic
Imbedded PDL fibers -
Sharpeys fibers -notspecific to cementum
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REDUCEDDENTALEPITHELIUM
HERTWIGSROOTSHEATH
DENTINE
Epithelial diaphragm
ROOT FORMATION
Odontoblast recruitment site
Root sheathbreaks up, allowingsac mesenchymalcells to contactroot dentine
DENTINE
PULP
Odontoblast recruitment site by root sheath: pulp signaling
Root sheath breaks up & lifts,allowing sac mesenchymal cellsto contact root dentine
CEMENTOGENESIS START
Dentine &/or Epithelial root
sheath induces mesenchymalcells to become cementoblasts
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Dentine formed beforecementum
& cervical before apical
Directions of
cementalgrowth -outwards &apicalwards
SEQUENCES
Osteoclasts
resorbing bone
PDL fibersincorporated in boneas Sharpeys fibers
FUNCTIONAL ERUPTION& TOOTH MOVEMENT
Osteoblasts
laying downbundle bone
Cellular cementum added to apexCompensates for occlusal wear?
Occlusal wear
Bonyinterdentalseptum
Basil
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PULP
CEMENTUM: Defects
CORONAL CEMENTUMspurs, etc, on enamel
HYPERCEMENTOSIS -
excess deposition
CEMENTOCLASIA - erodedcementum (occurs normally indecidual-tooth shedding)
CEMENTICLESIN PDL
CEMENTUM: Repair
After cementoclasia,cementoblasts may fillin the defect with newcementum.This cycle can be repeated,and also occurs a littleduring shedding & afterroot fracture
PU
LP
P
ULP
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EXFOLIATION of DECIDUOUS MOLAR III
Erosion of bone and the deciduous root is not steady &
continuous, but may cease briefly, when some repair oferoded cementum & dentine can occur (by cementum).
DENTINE
ENAMEL
P
ULP
CEMENTICLES
Hard mineralized bodies found inthe periodontal ligament orpartially imbedded in cementum
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DENTAL PAIN
Dental pain enters consciousness (HURTS) &becomes a major aspect of dentistry
What is the innervation of the tooth & periodontium?
How are these nerve fibers and endings relatedto dental pain?
How do the stimuli - heat, inflammatorymediators, etc - activate the nerve fibers?
What are the central pathways, structures, &interactions bringing pain to conciousness?
WABeresford
SENSITIVE?
DENTAL SENSITIVITIES
Dentine
Enamel
Cementum
Pulp
PDL
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PULP INNERVATION
Nerves: sensory (V) to
PULP
ODONTOBLASTS
DENTINAL TUBULES
Blood vessels
Nerves:
autonomic
1
2 3
1
2
3
Sub-odontoblastic plexus
in cell-poor zone of Weil
EXTENT of TOOTH INNERVATION
Fibers grow in during development & some transfer to20 tooth, so 20s have more nerves fibers than 10s
Sub-odontoblasticplexus of Raschkow
Hundreds of nerve fibers per tooth
Most fibers branch
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FIBER CALIBER & MODALITY
Hundreds of nerve fibersper tooth
10 % myelinated A fibers
80 % unmyelinated C fibers
No specialized receptors
< % A fibers
NOCICEPTION - pain - sensorymodality for pulp & dentine
1/2
FIBER FUNCTIONS
Autonomic roles
NOCICEPTION - pain - the sensorymodality for pulp & dentine
< % A fibers1/2
But what do these do?
Any trophic effects on
pulp from sensory fibers?
Hundreds of nerve fibersper tooth
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V
Sup CervicalGanglion
Branch of external
carotid A
Sympathetic fibers
PNS: AUTONOMICS
Pulp vesselOther targets?
Superior alveolar nerves
Inferior alveolar nerves
Trigeminal ganglion
Spinal nucleus of V
CNS
Convergencefrom several teeth onto one CNS neuron
PNS:CNS Sensory relations
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POOR LOCALIZATION
DULL ACHE
ACUTE, SHARP
Convergence
PAIN QUALITY
myelinated A fibers
unmyelinated C fibers
Inferior alveolar nerves
Trigeminal ganglion
Spinal nucleus of V
CNS
Sympathetic
PERIODONTAL LIGAMENT INNERVATION
Free ending
Ruffini receptorsMechanoreceptors for stretch
V Ganglion
Modalities: PROPRIOCEPTION & pain
Mesencephalicnucleus of V
Sup CervicalGanglion
CNS
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Reticular formation
Thalamic VPM
CNS: Dental pain pathways
Periaqueductalgrey (PAG)
SENSORY CORTEXParietal lobe
TRIGEMINAL NERVE
Mesencephalic N of V
Spinal V tractSensory V Nucleus
CNS
Spinal N V
Reticular formation
Thalamic VPM
CNS: Dental pain pathways
SENSORY CORTEX
TRIGEMINAL NERVE
Mesencephalic N
Spinal V tractSensory V Nucleus
Spinal N V Periaqueductal grey(PAG) can inhibitascending painsignals by usingendorphins, enkephalins
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Reticular formation sends signals everywhere
Sensory relays - Inhibitionof incoming & ascendingsensory signals
RETICULAR FORMATION: Roles
Motor nuclei - reflexes
Cortex - arousal
Hypothalamus -autonomic responses
Limbic system -emotions
NERVE-FIBER:STIMULI RELATIONS I
ODONTOBLASTS
Sub-odontoblastic plexus
2 3
Worn dentine brings stimulinearer to pulp
HeatColdPressure
Chemicals?
Enamel
Axons in tubules
Axons around
odondoblast bodies
ODONTOBLAST assensory transducer ?
Pulp
Direct pulpstimuli
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NERVE-FIBER:STIMULI RELATIONS II
ODONTOBLASTS
Pulp fibers sensitizedby factors releasedbecause of inflammation or previous activity
2 3
Worn dentine brings stimulinearer to pulp
HeatColdPressureChemicals
Enamel
Axons in tubules
Axons around
odondoblast bodies
Pulp
NERVE-FIBER:STIMULI RELATIONS III
HYDRODYNAMIC hypothesis of sensitivity
Axons aroundodondoblast bodies
ODONTOBLASTS
HeatColdPressure
Enamel
Axons in tubules
Stimuli move fluidback & forth in thetubule stimulatingtubule axons &/orodontoblasts
Dentine
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NERVE-FIBER:STIMULI RELATIONS IV
ODONTOBLASTS
HeatColdPressure
Enamel
Dentine
HYDRODYNAMIC hypothesis of sensitivity
Axons aroundodondoblast bodies
Stimuli move fluidback & forth in thetubule
with distortionof the odontoblast possibly causing it to releaseATP, and thus chemically exciting the axon - Alavi AM et al.Immunohistochemical evidence for ATP receptors in human pulp. J Dent Res2001;80:476-483
ODONTOBLAST assensory transducer ?
HYDRODYNAMIC hypothesis of sensitivity
Stimuli move fluid
back & forth in thetubule
with distortionof the odontoblast possibly causing it torelease ATP, and thus chemically exciting the axon - AlaviAM et al. Immunohistochemical evidence for ATP receptors in humanpulp. J Dent Res2001;80:476-483
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DENTAL PAIN: Unknowns
Stimulation mechanisms in pulp - normal & diseased
Reticular formation - what happens centrally
Patterns of firing - relation to perceptions
First Anatomy Journal about 1860; first Pain journal 1973
Allowed to work on animals only if pain is preventedor minimised
Animal cannot tell of pain; humans reluctant to let you
hurt them or do invasive investigations, e.g., nerverecordings
Many small nerve fibers used for other purposes,e.g., autonomic
No specialized pain endings? Defining pain stimuli?
Complex chemistry with tissue injury
Poorly understood dynamic interactions between
CNS & PNS - Pain is in the mind & usually in the body(CNS-PNS interactions: compare sexual arousal)
PAIN: Difficult to study
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TOOTH TISSUES: DENTINE
ALVEOLAR BONE
WABeresford
PULP
DENTINE
ENAMEL
CEMENTUM
PERIODONTAL
LIGAMENT/ PDL
GINGIVA
Blade Shaft Grip
ENAMELCEMENTUMDENTINE
TOOTH DESIGN: Spear me
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Blade Shaft Grip
ENAMELCEMENTUMDENTINE
TOOTH DESIGN: Spear me
ENAMEL CEMENTUMDENTINE
Shaft is hollow forPULP
Hand represented by
PERIODONTAL LIGAMENT& ALVEOLAR BONE
Refinements
Closer to true proportions
DENTINE: Role
Dentine is the major tissue of the tooth,acting as the living, hard, strong &resilient core, to which specializedtissues attach
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Dentine is themajor tissue ofthe tooth, actingas the living,hard, strong &resilient core, towhich specializedtissues attach
DENTINE: Correlates
MATRIX of collagen fibrils andglycoproteins & proteoglycans -
STRENGTH & RESILIENCE
mineral crystals - HARDNESS
ODONTOBLASTS & their processes -
LIVING
PULP
DENTINE
CEMENTUM
DENTINE: Position
ENAMEL
CROWN
Cervix
ROOT
}}
CROWN/CORONAL
DENTINE
ROOT/RADICULAR
DENTINEversus
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DENTINE: Boundaries
Dentino-enamel junction DEJ
Dentino-cemental junction DCJ
Pulp surface
APICAL FORAMEN
Orally exposed - pathological
Odontoblastsin an epithelial-like layer
DENTINE: Composition
MATRIX of collagen fibrils, mineralcrystals, and glycoproteins & proteoglycans
Penetrated by TUBULES containing long thinprocesses of cells - ODONTOBLASTS -whose bodies lie outside and against the
pulpal surface of the dentine
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DENTINE: Composition
MATRIXPROPORTIONS
collagen fibrils andglycoproteins &
proteoglycans 30%Organic
mineral crystals 70%Inorganic
MATRIX of collagen fibrils, mineralcrystals, and glycoproteins & proteoglycans
TUBULE
DENTINE: Composition II
MATRIX subdivided into
TUBULES 1-3 m wide
Peritubular dentine Neumanns sheath
Inter-tubular dentine
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DENTINE: Reality
Matrix-tubule ratios vary
Tubules curve
Processes split
Processes extendinto enamel rare
ENAMEL
SPINDLES
DENTINE: Growth
Odontoblasts
Enamel PREDENTINE
DENTINE
Direction of growth -
pulpward from DEJ
Matrix color as seen with H&E:dense collagen gives a red color, butpredentine is paler. Matrix fibrils areunseen.
Enamel is
removed by the
decalcification
needed for wax
sections
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TOOTH GERM: Odontoblast recruitment
DENTALPAPILLAbecoming
pulp
outermost papillacells have becomeOdontoblasts
Recruitment site
Ingrowing pulp vessels
TOOTH GERM:Dentinogenesis
DENTALPAPILLAbecomingpulp
cusp Dentineformed by
OdontoblastsRecruitment site
for odontoblasts
Ingrowing pulp vessels
Dentine is formed first as predentine -organic phase precede mineralization
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PULPA
L
ORIENTATION: Terms
CUSPAL/OCCLUSAL
APICAL
CERVICAL {
CORONAL
RADICULAR
Enamel
Cementum
Dentine first formed at CEJ
Coronal dentine formedbefore root dentine, AND
cuspal before cervical, &cervical before apical
Pulpal-surface dentine is
formed last
Odontoblast
trajectoriesduring growth
SEQUENCES
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Dentine first formed at CEJ
Odontoblasttrajectoriesduring growth
INCREMENTAL GROWTH
Contour lines of Owen reflectvarying physiologicalcircumstances during growthneonatal line is most prominent
This view tries to show
something of the appearance of
the ground section of tooth. Tosee detail, the glare needs to betaken out by closing the irisdiaphragm (the lever on thecondenser) as required
P
ULP
MATURE DENTINE: Varieties
MANTLE DENTINE justbelow DEJ coarser fibrils
CIRCUMPULPAL DENTINE -main mass of dentine
TERTIARY DENTINE* - slow
increment to pulpal surface
{
REPARATIVE DENTINE* -response to caries/erosion
* * Response relies on the pulp and theodontoblasts staying alive & active
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PUL
P
REPARATIVE DENTINE 2
REPARATIVE DENTINEin response to attrition/wear ofthe cusp
P
ULP
MATURE DENTINE: Defects
CARIOUS DENTINEwide bacteria filled tubules
INTERGLOBULAR AREASlack mineral
DEAD TRACT -wide, empty dentinal tubuleseasily colonized by bacteria
TOMES GRANULAR LAYERholes in root dentine near DCJ
SCLEROTIC DENTINE -tubules filled with mineral
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MATURE DENTINE: Usual Defects
PULP
INTERGLOBULAR AREASlack mineral
TOMES GRANULAR LAYERholes in root dentine near DCJ
SCLEROTIC DENTINE -tubules filled with mineral
normal development
normal aging
INTERGLOBULAR AREAS lackmineral & appear as black batswings in the ground section. Theyrepresent incomplete expansion ofthe spherical (globular)mineralising foci in the predentine
P
ULP
Interglobular areas are close to the CEJ,but may be seen in radicular dentine
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PULP
DENTINTICLES/ PULP STONES
Hard mineralized bodies found inthe pulp or the dentine
TWO TYPES:
1 TRUE - constructed of dentine
by odontoblasts & showingdentinal tubules
2 FALSE - mineralized connective
tissue, etc, (not made of dentine)
Both may show layering/lamellar patterns from
incremental growth
P
ULP
DENTINTICLES/ PULP STONES:further classification by place
Hard mineralized bodies found in the pulp orthe dentine
THREE SUBTYPES:
1 FREE - in the pulp
2 IMBEDDED - enclosed in thedentine as this has slowly grown
inwards
3 ATTACHED - partly imbedded
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TOOTH TISSUES: ENAMEL
ALVEOLAR BONE
WABeresford
PULP
DENTINE
ENAMEL
CEMENTUM
PERIODONTAL
LIGAMENT/ PDL
GINGIVA
Blade Shaft Grip
ENAMELCEMENTUMDENTINE
TOOTH DESIGN: Spear me
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TOOTH DESIGN: Spear me
ENAMEL CEMENTUMDENTINE
Shaft is hollow forPULP
Hand represented byPERIODONTAL LIGAMENT& ALVEOLAR BONE
Refinements
Closer to true proportions
ENAMEL: Role
Enamel is the dead, very hard,but brittle cutting/grindingoral covering of the tooth
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PULP
DENTINE
CEMENTUM
ENAMEL: Position
ENAMEL
CROWN
Cervix
ROOT
}
}
ENAMEL: Boundaries
Dentino-enamel junction DEJ
Orally exposed surface with acquiredPELLICLE
Cemento-enamel junction - CEJ
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E E
D D
E
D
CEMENTUM: CEJ VARIATIONS
OVERLAP C/Emost frequent
GAPdentine exposed
BUTT JOINTend-to-end
CEMENTUM
60% 10%30%
ORIENTATION: Terms
CUSPAL/OCCLUSAL
APICAL
CERVICAL
CORONAL
P
ULPAL
{
Enamel
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ENAMEL: Nature
Enamel is the dead, very hard, but brittle cutting/grinding oral covering of the tooth
This degree of hardness can be achieved by thedense packing of curved rods/prismscomposedalmost entirely of densely arranged spikey mineralcrystals, with a keying together of the prisms
R
OD
RO
D
Mineral is hydroxyapatite, withCa2+, OH-, PO4
--, etc, ions
Cross-section of rods
Hardness from material & interlocking devices
ENAMEL
DEJ
PRISMS/RODS
Enamel is 96% large mineralcrystals arranged as long wavyinterlocked rods/ prisms
Demarcation between prisms
is called the ROD SHEATH -more organic, slightly lessmineral
Enamel is:96% mineral,3% water,1% organic material
First enamel is NON-PRISMATIC
Last enamel is NON-PRISMATIC
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Enamel
Enamel first formed at DEJ
Cusp enamel formedbefore cervical
Ameloblasttrajectoryduring growth
SEQUENCES
Enamel growsoutwardsfromthe DEJ
One ameloblastmakes one prism/rod
DEJ Story I
Mesenchyme
Starts as basal
lamina betweeninner epithelial cells
& dental-papilla cells
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DEJ Story II & III
Continues as basal laminabetween inner epithelialcells & odontoblasts (2nd)
Goes on to be a basal lamina
between inner epithelial cells& dentine (third step)
cusp enamelformed by
ameloblasts
DEJ Story IV
Dentine instructs inner epithelialcells to become ameloblasts -through an intact, then through adisintegrating basal lamina?
Ameloblasts lay downenamel matrix on thedentine to create the DEJ
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DEJ Story V & VI
DEJ is actually a little irregular,as a serrated or scalloped lineseen in ground sections
ENAMELSPINDLE
Odontoblast process stuck intoenamel matrix while it was soft,
thus crossing the DEJ
E
D
Cross-section of rods
ENAMEL: Problems
PROBLEMS:
the precise wear-resistant architecture needsa prior cell-oriented organic precursor
a maturation phasehas to replace the
organic with inorganic mineral
the direction of growth outward from the DEJleaves the formative cells on the surfacewhere they cannot survive- no later repairpossible
deleterious agents can substitutefor ions inthe crystal lattice, e.g., Pb, Sr90, Fl, &
tetracycline can bindto the mineral
ROD R
OD
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Ameloblast
Tomes process
ROD
ENAMEL FORMATION - AMELOGENESIS
COMPARTMENT FORSECRETORY RELEASE
Organic first deposits,e.g., amelogenin, + 30%mineral
organic materials digested;replaced by mineral to 96% -
maturation
DEJ DEJ
Ameloblast
Tomes process
ROD
AMELOBLASTS TOMES PROCESS
COMPARTMENT FORSECRETORY RELEASE
Releases vesicles ofamelogenin, etc
later releases enzymes to digestorganic matrix (replaced bymineral to 96%- maturation)
transports ions into matrix
Process defined by terminalweb of actin etc stretchingbetween junctional complexesfastening ameloblasts together
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Ameloblast
ROD
AMELOBLASTS VASCULAR RELATIONS
Outer dental epithelium
BASAL LAMINA
CAPILLARY
Collapse of stellatereticulum lets vesselsapproach closer to the
highly active ameloblasts
Stratum intermedium
TOOTH GERM
DENTAL LAMINAupper degenerateslower forms 2nd bud
Outer dental epitheliumcollapsing down
Stellate reticulumreducing over cusp
Cervical loopdefines extent ofcrown to crownbase; then itstarts the rootsheath
DENTALPAPILLAbecomingpulp
DENTAL SACquiescent
Knot cells signalto papilla outermost papilla
cells have become
Odontoblasts
Recruitment site
Ingrowing pulp vessels
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TOOTH GERM:
result & next steps
Stellate reticulummoving apically
cusp Dentineformed byOdontoblasts
Dentine is formed first as predentine.
It will signal to inner dental
epithelial cells to become ameloblasts
TOOTH GERM: all crown-forming elements present
Ameloblasts
Stellate reticulum
DENTAL SACstill quiescent
cusp enamelformed byameloblasts
Capillaries now close to
synthesizing ameloblasts
Dentine
Enamel is always
less extensive than
dentine
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DENTALPAPILLAbecomes pulpprocessproceedsdowns
Stellate reticulumfollows Cervical
loop down thenstops: Crown
defined
Second reductioninenamel epithelium:
retired ameloblasts &compacted outerepithelium, stellate-reticulum cells &stratum intermedium
CHANGES IN DENTAL/ENAMEL ORGAN III
Ameloblasts
will finish fullthickness of
cusp enamel& reduce inheight
Dentine widens
Cervical loop:
Odontoblast
recruitment
site
Where Stellatereticulumstopped, thecervical loop
continued togrow down, butas
ENAMEL
REDUCEDDENTALEPITHELIUM
HERTWIGSROOT SHEATH& its
DENTINE
PULP
Epithelial diaphragm
CROWN
CROWN COMPLETED
Odontoblast recruitment site
ROOT
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REDUCEDDENTAL
EPITHELIUM will
fuse with gingiva
ROOT FORMATION: Coronal consequences
GINGIVALEPITHELIUM
As root
lengthenscrown ispushed up -Pre-EMERGENCE
HERTWIGSROOTSHEATHgrows tolengthen root
Connective
tissue brokendown
REDUCEDDENTAL
EPITHELIUM
protects
enamel
ENAMEL
REDUCED DENTAL
EPITHELIUM
TOOTH EMERGENCE
GINGIVALEPITHELIUM
still fusing with
CUTICLEwill wear away
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ORGANIC ENAMEL SURFACE
CUTICLEwill wear away
PELLICLE ofglycoproteins etc isacquiredlater from saliva
PLAQUEthe biofilmof many kindsof bacteria then attachesto the pellicle
INCREMENTAL GROWTH
Contour lines of Retziusreflect varying physiologicalcircumstances during growthneonatal lineis most prominent
As ameloblasts make prisms, diurnalfluctuations in their physiology
produce faint striationsacross therods
Unless erased by wear, perikymataare a mild ripple effect seen on thesurface of enamel from the slightly
differing qualities of enamelremember the flat-wet-sand, low-tide effect
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ENAMEL IN HISTOLOGY
Being 96% mineral, enamel makesteeth too hard to cut for imbedded& stained sections
Demineralization with acid or achelator, for H&E sections destroysmature enamel, creating a space
Demineralization for H&E leavessome of the immature enamel ofearly formation, particularly in thelast-formed cervical region
Ground sections, unstained, preservemature enamel, but may introduce cracks
immatureENAMELmatrix remains
REDUCEDDENTALEPITHELIUM
DENTINE
PULP
AFTER DEMINERALIZATION
space wherematureENAMEL hasbeen lost
most recentlyformed, henceimmature
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TUFT
GNARLEDENAMEL
ENAMEL: Special features
LAMELLA
FISSURE/PIT
SPINDLE
ENAMEL: Special features FISSURE/PITAmeloblastswere cramped
while makingenamel
ENAMELSPINDLE
Odontoblastprocess stuck intoenamel matrix
while it was soft
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LAMELLA
TUFT
GNARLED
ENAMEL
ENAMEL: Special features Mostly visualeffect from varied
rod directions
Mostlyvisualeffectfromunusually
varied roddirections
Vertical cracks filledwith mineralizedorganic material
Lamellae are seen incoronal cross-sections
PULP
ENAMEL: minor defect
CORONAL CEMENTUMspurs, etc, on enamel
Reduced enamel epitheliumhad gaps that allowedmesenchymal cells in tobecome cementoblasts
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MATURE ENAMEL: Severe Defects
PULP
ATTRITION/ WEAR
CARIES/DECAY
Any loss is severe since thereare no ameloblasts to replace it
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PULP
DENTINECEMENTUM
PERIODONTAL
LIGAMENT/ PDLALVEOLAR BONE
WABeresford
ROOT FORMATION & ERUPTION
What has to be controlled
Shedding of teeth
Number of roots
Shapes of root
Times of eruption
Four tissues in sequence
Organize surroundings
Fasten tooth to surroundings
Successional teeth
Length of root
Pulp Dentine Cementum Ligament
& coordinatede.g., cementum with PDLwith bone
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TOOTH TISSUES: Cell Sources
DENTAL LAMINA
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
DENTAL ORGAN
ALVEOLAR BONE
PULP
DENTINE
ENAMEL
CEMENTUM
PDL
A BONE
TOOTH
Crest
Ameloblasts
Odontoblasts
CT cells
Cementoblasts
Fibroblasts
Osteoblasts & clasts
Deposition of alveolar bone?
MECHANISMS OF ERUPTION
Formation of the root
Construction & Reorganization of PDL
Remodelling of bone overall
FURTHER INFLUENCES from: tooth/teeth in occlusion; muscle actions
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TOOTH GERM:
next stepsDENTAL LAMINAupper part degenerateslower forms 2nd bud
Outer dental epithelium
approaches inner
Stellate reticulumreduces over cusp
Inner & outer dental epitheliajoin to form cervical loop
Stratum intermedium
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
Knot cellssignal topapilla
First reductioninenamel epithelium:active ameloblasts &
compacted outerepithelium, stellate-reticulum cells &
stratum intermedium
LATE CROWN FORMATIONcusp enamelformed byameloblasts
Dentine
Cervical loop:inner & outerepithelium
DENTALPAPILLA
become pulp
remainingStellate reticulum
DENTAL SACstill quiescent
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DENTALPAPILLAbecome pulpprocessproceedsdowns
Stellate reticulumfollows Cervical
loop down thenstops: Crown
defined
END OF CROWN
FORMATION
Ameloblasts
will finish fullthickness of
cusp enamel& reduce inheight
Dentine widens
Cervical loop:
Odontoblast
recruitment
site
Where Stellatereticulumstopped, thecervical loop
continued togrow down, butas
ENAMEL
REDUCEDDENTALEPITHELIUM
HERTWIGSROOT SHEATH& its
DENTINE
PULP
Epithelial diaphragm
CROWN
ROOT FORMATION
Odontoblast recruitment site
ROOT
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ENAMEL
REDUCED
DENTALEPITHELIUM
HERTWIGS
ROOTSHEATHgrows tolengthen root
DENTINE
PULP
Epithelial diaphragm
FURTHER ROOT FORMATION
Odontoblast recruitment site
Root sheathbreaks up, allowingsac mesenchymalcells to contactroot dentine
Other sacmesenchymal
cells constructPDL & somealveolar bone
Fibroblasts
ROOT SHEATH & ITSDIAPHRAGM widens& constricts to createtwo diaphragms todefine two roots
Epithelial diaphragm
ROOT FORMATION: Multirooted
ENAMEL
DENTINE
PULP
CROWN
ROOT
ROOT SHEATH
Cross-sections
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Thus, one dental organcan produce two orthree roots
ROOT FORMATION: Multirooted
Epithelial diaphragm ROOT SHEATH
ENAMEL
DENTINE
PULP
CROWN
ROOT
Similarly, one dentalorgan can producetwo or more cusps,
using multipleenamel knots
ENAMEL
REDUCED DENTALEPITHELIUM
DENTINE
PULP
Odontoblast recruitment site by root sheath: pulp signaling
Root sheath breaks up & lifts,allowing sac mesenchymal cellsto contact root dentine
REITERATIVE SIGNALING V
Dentine &/or Epithelial rootsheath induces mesenchymal
cells to becomecementoblasts
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JAW & TOOTH DEVELOPMENT early arch
BONE startingLINGUAL PLATE
BONE startingBUCCAL PLATE
SYMPHYSEALCARTILAGE
10 TOOTH GERM
20 SuccessionalTOOTH GERM
DENTAL LAMINA
WALLS OF BONYTROUGH OF
DEVELOPINGMANDIBLE
JAW & TOOTH DEVELOPMENT processes
BONE startingLINGUAL PLATE
BONE startingBUCCAL PLATEgrows up morethan lingual
SYMPHYSEAL CARTILAGEwill be replaced by bone
10 TOOTH GERM
20 Successional TOOTH GERMon lingualside of 10
DENTAL LAMINA will grow back to formgerms for 3 permanent molars (5th e m)
Bony wall grows around& encloses 20 TOOTHGERM in a crypt
Interdental septum
grows across troughto separate teeth
Interradicular septum
grows between rootsof multirooted teeth
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TOOTH & MANDIBLE DEVELOPMENT
10 TOOTH
20 TOOTH GERM
MECKELSCARTILAGE
TONGUE
ALVEOLARBONE
DENTAL SAC
ALVEOLARNERVE
Oral ectoderm
Bone added tobase of alveolusfor tooth eruption
10 TOOTH
20 TOOTHGERM
MECKELSCARTILAGE
Alveolar crestgrows up
regresses & notused to formmandible
Bony plate grows upto enclose 2nd toothgerm in a CRYPT
Bone grows overalveolar nerve &vessels
Alveolus becomesdistinct from BODY
DENTAL SAC contributesalso to alveolar bone
MANDIBLE DEVELOPMENT
Remodeling will bring erupting1o tooth over developing 2o
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10 TOOTH
20 TOOTH GERM
MECKELS
CARTILAGE
TONGUE
ALVEOLAR
BONE
DENTAL SAC
ALVEOLAR
NERVE
Reduced enamel epitheliumfused with gingiva
Higher alveolar bone- i.e. deeper socket
Longer root withcementum forming
More advanced 2nd tooth
Denser alveolar bone & morebody-alveolus distinction
Meckels cartilage gone
TOOTH & MANDIBLE DEVELOPMENT - Next
Remodeling brings erupting 1o
tooth over developing 2o
ENAMEL
REDUCED DENTAL
EPITHELIUM
TOOTH EMERGENCE
GINGIVALEPITHELIUM
still fusing with
CUTICLEwill wear away
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ORGANIC ENAMEL SURFACES
CUTICLEwill wear away
PELLICLE ofglycoproteins etc isacquiredlater from saliva
PLAQUEthe biofilmof many kinds
of bacteria then attachesto the pellicle, & latermineralizes - tartar
DENTINE
ENAMEL
BONE
GINGIVA
Epithelial diaphragm
ROOT SHEATH
CEMENTUMPDL
PULP
Cementum starting assheath breaks down
LATE ERUPTING TOOTH
Rests of Mallassezremnants of Root sheath
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Epithelial diaphragm
ROOT SHEATH
LATE ERUPTING TOOTH
DENTINE
ENAMEL
BONE
GINGIVA
CEMENTUMPDL
PULP
Rests of Mallassezremnants of Root sheath
Cementum starting assheath breaks down
Deciduous tooth
Gingiva
Cortical platedense bone
BODY ofMANDIBLE
ALVEOLAR BONE
PDL
Permanenttooth
MANDIBULAR CENTRALINCISORS at 2 y
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Gubernacular cord offibrous tissueGubernacular cord
runs through a canalleft in the bony crypt,where the dentallamina extendeddown to establish thegerm for the 2ndtooth
Permanenttooth
Go Gubba
Deciduous tooth
Cortical platedense bone
Permanenttooth
MANDIBULAR CENTRALINCISORS at 2 y - Bone
Spongy/ cancellous bone
Resorption of bone& deciduous rootwill start here
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10/Deciduous tooth
PDL attachment issurprising persistent
Close to EXFOLIATIONof Deciduous/10 Tooth
Bone trabeculaeadded by layers atbase of alveolus
Odontoclasts haveresorbed most ofdeciduous root
Pulp is leftalive
Bone remodelllinghas brought 20 tooth
under 10
20 tooth would beLARGER than shown
20 tooth
DENTINE
ENAMEL
BONE
GINGIVA Oral Ectoderm
Epithelial diaphragm
ROOT SHEATH Dental organ
CEMENTUM Dental sacPDL
PULP
PDL Dental sac
LATE ERUPTING TOOTH: Origins
Rests of Mallassezremnants of Root sheath
BONE Arch Mesenchyme & Dental sac
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WHY STILL ERUPTING
DENTINE
ENAMEL
BONEPDL
PULP
APEX INCOMPLETE
Pulp chamber wide(no apical taper)
Cementum not to apex
& Bone forming in base of alveolus
Epithelial diaphragm present
Immature connective tissue
STARTING EXFOLIATION of DECIDUOUS MOLAR I
ALVEOLARBONE
DENTINE
ENAMEL
Permanent Tooth under deciduousmolar, & between its roots
Inter-radicular septum of bone alsohouses 2nd tooth germ & is its crypt
Root resorptionby osteoclasts
PDL
PULP
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EXFOLIATION of DECIDUOUS MOLAR II
ALVEOLARBONE
DENTINE
ENAMEL
Focal erosion along this lineleaves a ROOT FRAGMENTwhich may be retained
Resorbed dentine partlyrepaired by new cementum
Crypt boneeroded here
PDL
PDL is disrupted in regions ofroot resorption & repair
EXFOLIATION of DECIDUOUS MOLAR III
Erosion of bone and the deciduous root is not steady &continuous, but may cease briefly, when some repair oferoded cementum & dentine can occur (by cementum).
Bone remodelling also goes on, and the alveolus andcrypt are changing all the time - repeated all along the jaw
DENTINE
ENAMEL
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Osteoclastsresorbing bone
PDL fibersincorporated in boneas Sharpeys fibers
FUNCTIONAL ERUPTION& TOOTH MOVEMENT
Osteoblastslaying downbundle bone
Cellular cementum added to apexCompensates for occlusal wear?
Occlusal wear
Bony
interdentalseptum
Basil
TOOTH MOVEMENT
Osteoblasts
laying downbundle bone
Tooth drifts mesiallyby combined actionsof osteoclasts &osteoblasts movingbone, taking toothwith it
Basil
Osteoclastsresorbing bone
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TOOTH MOVEMENT
Tooth drifts mesially bycombined actions ofosteoclasts & osteoblastsmoving bone, taking toothwith it
Basil
Earlier boneposition
Intra-oral phase
TOOTH ERUPTION
Pre-oral phase
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Once the teeth meet inocclusion, their furthereruption separates the jaws
TOOTH ERUPTION
Once the teeth meet inocclusion, they influenceeach other mechanically
PERIODONTITIS
Periodontalligament
TOOTH
Alveolar bone
GINGIVA
EPITHELIAL ATTACHMENT-unstable, loosens &migrates down, & allowsbacteria into
CONNECTIVE TISSUE
resulting in chronicinfection &
inflammation &
systemic spread ofbacteria &
loss of teeth
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Gingival recession onto &down the cementum with lossof alveolar-crest bone
PASSIVE ERUPTION
Raising the banana, then peeling the banana
P
ULP
Fate of exposed cementum &dentinal consequences & reactions
Cementum readily abraded &
eaten by oral acids
REPARATIVE DENTINE -response to caries/erosion
DEAD TRACT in Dentine -wide, empty dentinal tubuleseasily colonized by bacteria
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TOOTH MOVEMENTS
DRIFTING e.g., mesially, laterally
AXIAL - in long axis of the tooth
Basil
Occurring in eruption & use
ROTATORY
TILTING
By root growth &bone remodelling
By bone remodelling &PDL reorganization
Combinations of these fourmovements frequently occur
TOOTH MOVEMENT 2
Basil
Earlier boneposition
TILTINGTooth tilts by combinedactions of both osteoclasts& osteoblasts on bone of
each sideof socket
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3rd MOLARS TILTING ERUPTION
TILTING mechanism may be useful, e.g., in bringingupright the third molar that starts tilted
Failure can lead to an impacted molar still within the bone
2nd2nd
3rd
3rd
1 32 54 760YEARS
YOUNG CHILDS ERUPTION SEQUENCE
Time of emergence
Root formingCrown forming
KEY
10 2nd Molar
20 Incisor
20 Cuspid
20 2nd PreMolar
Deciduous
Permanent
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10 Incisor
10 Cuspid
1 32 54 760YEARS
YOUNG CHILDS ERUPTION SEQUENCE
10 2nd Molar
20 Incisor
20 Cuspid
20 2nd PreMolar
5-yr CHILDS DENTITION: 0ne arch
5 deciduous teeth working, but 1o incisor root is being resorbed
7 successional/succedaneous teeth developing pre-orally
dental lamina for 3rd molar
Oral
Pre-oral
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5-yr CHILDS DENTITION: 0ne arch
These 12 teeth require a very coordinated remodelling of thebone (& PDL) supporting & enclosing them
Oral
Pre-oral
ERUPTION: Problems
Early eruption
Missing tooth
Impaction - failure to erupt e.g., from too little gap afterpremature loss of deciduous tooth
Delayed eruption
Malocclusion
Tilting (can occur early from germ rotation)
Infra-occlusion (not high enough)
Retained root fragment
Excessive drift
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GINGIVA: Roles
Establishes a seal around the tooth
Adapt to changing oral conditions & eruption
Fastens to the tooth along an extensive area
Connect soft tissue to hard while it
Control oral microbes
Attaches firmly to the bone supporting the tooth
Join with the adjacent aveolar mucosa
Provide sensation for control of biting & chewing
Protect the PDL & alveolar bone
WABeresford
Free & attached gingiva
FREE GINGIVA
ATTACHED GINGIVA
}Epithelial
attachment
TOOTH
Gingival sulcus/ crevice
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GINGIVAL EPITHELIUM
Stratified squamouspara-keratinized
very protective barrier,
needing glandularlubrication
piled-up, tightlyattached, & internallyreinforced cells
GINGIVAL EPITHELIUM: Cell types
Keratinocytes
Langerhans APC cell
Melanocyte
Merkel cell
Nerve cell (axon)
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GINGIVAL EPITHELIUM: Cell types
Keratinocytes
LangerhansAPC cellimmunity
Melanocyte tomake & transferpigment
Merkel cellsensory
dead
alive
Nerve cell representedby its axon
GINGIVAL EPITHELIUM: Subtypes
GINGIVAL EPITHELIUM*
SULCULAR/CREVICULAR
EPITHELIUM
Gingival sulcus/ crevice
TOOTH
CUFF/ ATTACHMENTEPITHELIUM
*Keratinization
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EPITHELIAL ATTACHMENT
TOOTH
JUNCTIONAL/ CUFF/ATTACHMENT EPITHELIUM
CUTICLE
BASAL LAMINA
TOOTH
GINGIVA
Alveolarbone
MATRIX -
Ground substanceCollagen I & III fibersElastic fibers
Blood vessels
Nerves, receptorsLymphatics
CELLS -
Fibroblasts & MyofibroblastsMacrophagesMast cellsLeukocytes
GINGIVAL ELEMENTS - Dense connective tissue
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TOOTH
Alveolarbone
Fibroblasts & MyofibroblastsMacrophagesMast cellsLeukocytes
GINGIVAL ELEMENTS - Connective tissue cells
Leukocytes, particularly PMNs &lymphocytes, are very numerous
& infiltrate the epithelium
GINGIVA
The gingiva is in a continuous
inflammatory state
PERIODONTITIS
Periodontalligament
TOOTH
Alveolar bone
EPITHELIAL ATTACHMENT-unstable, loosens &migrates down, & allowsbacteria into
CONNECTIVE TISSUE
resulting inchronic infection &
inflammation &
systemic spread ofbacteria &
loss of teeth
GINGIVA
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GINGIVAL FIBER GROUPS
TRANS-SEPTAL inmedio-distal plane,not shown here
DENTO-GINGIVAL
ALVEOLO-GINGIVAL
GINGIVA
Alveolarbone
CIRCULARDENTO-PERIOSTEAL
Periosteum
TOOTH
TRANS-SEPTAL FIBER GROUP
TRANS-SEPTALin medio-distalplane
Alveolarseptum
TOOTH TOOTH
GINGIVA
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GINGIVAL FIBER GROUPS
DENTO-GINGIVAL
ALVEOLO-GINGIVAL
TOOTH
GINGIVA
Alveolarbone
TRANS-SEPTALif in medio-distalplane, not as
shown here
CIRCULAR
DENTO-GINGIVAL
ALVEOLO-GINGIVAL
CIRCULAR
TRANS-SEPTAL
DENTO-PERIOSTEAL
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PERIODONTAL LIGAMENT/ PDL
PULP
DENTINE
ENAMEL
CEMENTUM
PERIODONTAL
LIGAMENT/ PDLALVEOLAR BONE
GINGIVA
WABeresford
TOOTH DESIGN: Spear me
ENAMEL CEMENTUMDENTINE
Shaft is hollow forPULP
Hand represented byPERIODONTAL LIGAMENT& ALVEOLAR BONE
Refinements
Closer to true proportions
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PERIODONTAL LIGAMENT: Roles
The PDL is the means of attaching the toothto the muscle-driven bone for mastication.As a labile connective tissue, it:
adapts the strengthand orientation ofattachment to varying load
senses loadsfor proprioceptive feebackcontrolling muscle actions
helps to move the teethfor better occlusion
supplies & nourishescementum & alveolarbone
defendsagainst microbes
repairsdamage to itself, while preventing
damage to cementum
CONNECTIVE TISSUE ROLES: PDL
Connect/Support
Transport/Nourish
Defend
(Storage)
Control
Repair
Connective tissue
EPITHELIUM
VESSEL
}
The tissues served are also bone & cementum
*
*
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CONNECTIVE TISSUE - Mechanical functions
Supporting - ligament, cartilage, bone
Binding - ligament
Restraining - ligament
Directing - tendon
Separating - fascia
Padding - fat pad
Functions, including padding, all effected by PDL,but adipose tissue is absent
DENSE REGULAR CONNECTIVE TISSUE: Tendon
Bundles of thick
collagen I fibers
{
{
Looser vascular CT
between the bundles -
endotendinuem
Elongated fibroblasts - tenocytes
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DENSE REGULAR CONNECTIVE TISSUE: PDL
Bundles of thickcollagen I fibers
{
{
Looser vascular CTbetween the bundles
- interstitial areasElongated PDL fibroblasts
PRINCIPAL FIBERS
DENTINE
PULP
PDL Interstitial Areas
OBLIQUE & other
FIBER BUNDLES
Interstitial Areas
between
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PDL ELEMENTS - Dense & loose connective tissue
MATRIX -Ground substanceReticular fibersCollagen I fibers
Blood vesselsNervesLymphatics
CELLS -Fibroblasts & MyofibroblastsMacrophagesMast cellsLeukocytesCementoblastsOsteoblasts & clasts
& Cementicles & Rests
PDL ELEMENTS - The elastic question
MATRIX - Ground substance Reticular fibers Collagen I fibers
The PDL, like tendon, has the elasticity of bundledcollagen fibers in a water-containing matrix ofproteoglycans & glycoproteins. But it does NOTcontain elastic fibers.
The complication is that elastic fibers comprisemicrofibrilsorienting the elastin, & these are separatemolecular species that have to assemble. The PDLdoes have the microfibrils arranged as OXYTALANfibers. Why? No-one knows.
The final complication is that there is an a fiberintermediate between the elastic & oxytalan fibers - theELAUNIN fiber, also absent from the PDL. Forget it.
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DENTINE
ENAMEL
BONE
GINGIVA
Epithelial diaphragmROOT SHEATH
CEMENTUMPDL
PULP
Cementum starting assheath breaks down
LATE ERUPTING TOOTH
Rests of Mallassezremnants of Root sheath
DENTINE
ENAMEL
BONE
GINGIVA
Epithelial diaphragm
ROOT SHEATH
CEMENTUM
PDL
PULP
PDL BOUNDARIES
BONE
CEMENTUM
GINGIVA
PULP
Mature
+ while developing
ROOT SHEATH
MESENCHYME
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TOOTH TISSUES: Cell Sources
DENTAL LAMINA
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
DENTAL ORGAN
ALVEOLAR BONE
PULP
DENTINE
ENAMEL
CEMENTUM
PDL
A BONE
TOOTH
Crest
Ameloblasts
Odontoblasts
CT cells
Cementoblasts
Fibroblasts
Osteoblasts & clasts
TOOTH GERM: all crown-forming elements present
Ameloblasts
Stellatereticulum
Cervical loopmoving apically
to define extent
of crown
DENTALPAPILLAbecomingpulp
DENTAL SACstill quiescent
cusp enamelformed byameloblasts
Capillaries now close to
synthesizing ameloblasts
Dentine
2nd
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ENAMEL
REDUCED
DENTALEPITHELIUM
HERTWIGS
ROOTSHEATHgrows tolengthen root
DENTINE
PULP
Epithelial diaphragm
FURTHER ROOT FORMATION
Odontoblast recruitment site
Root sheathbreaks up, allowingsac mesenchymalcells to contactroot dentine
Other sacmesenchymal
cells construct
PDL & somealveolar bone
Fibroblasts
E
D
E
D
Reactivated cementoblastslay down cementoid
E
D
E
D
GROWTH OF CEMENTUM = PDL anchoring
Cementoid becomesanother layer of cementum.Cells make more cementoid
PDL
fibers
PDL fibers becomeimbedded in newlyformed cementum -
Sharpeys fibers
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CERVICAL REGION
Periodontalligament
TOOTH
Alveolar bone
GINGIVA
EPITHELIAL ATTACHMENT-
CONNECTIVE TISSUE
PDL CERVICAL FIBER GROUPS
TOOTH
GINGIVA
Alveolarbone
(GINGIVAL LIGAMENT)
TRANS-SEPTALif in medio-distalplane, not asshown here
ALVEOLAR-CREST
HORIZONTAL
CEMENTUM
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PDL TRANS-SEPTAL FIBER GROUP
TRANS-SEPTALin medio-distalplane
Alveolarseptum
TOOTH TOOTH
GINGIVA
DENTINE
PULP
PDL FIBER GROUPS II
HORIZONTAL
OBLIQUEthe major group
APICAL
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III PDL INTER-RADICULAR GROUP
Inter-radicular
Inter-radicularbony septum
FIBER GROUPS: A classification
Inter-radicular
Horizontal
Oblique
Apical
Alveolar-crest
GINGIVAL LIGAMENT
ALVEOLO-DENTAL
Trans-septal
INTERDENTAL
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D
E
N
T
I
N
E
PULP
Non-imbeddedends of PDL fibers
meet & attach inINTERMEDIATEPLEXUS
{
This arrangementprovides for greater
ease of remodelling &readjustment of theplexus for growth &altered function. Butremodelling occursthroughout the PDL
PDL: Intermediate plexus
TOOTH MOVEMENT
Osteoblasts
laying downbundle bone
Tooth drifts mesiallyby combined actionsof osteoclasts &osteoblasts movingbone, taking toothwith it
Osteoclastsresorbing bone
Plus PDLreorganization
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Interstitial AreaPDL in Cross-sectionWider on bone-
depository side
Bundle
Narrow on bone-resorptive side
DENTINE
PULP
BONE
CEMENTUMP
D
L
Reduction in # &size of principal
fibers
Periodontal reactions to disuseLoss ofalveolar bone
Bundledefinitionlost
PDLnarrower allaround
DENTINE
PULP
BONE
CEMENTUMthickensP
D
LCEMENTUMlosesSharpeysfibers
Mild bonedepositionon wall
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RESTS & CYSTS
DENTINE
ENAMEL
BONE
ROOT SHEATH
PDL
PULP
Rests of Mallassezremnants of Root sheath
Any buried epithelial cells can proliferate &start to secrete, forming a cyst., e.g., remnantsof dental lamina, thyroglossal duct, etc
P
ULP
CEMENTICLES
Hard mineralized bodies foundentirely in the periodontal ligamentor partially imbedded in cementum
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WABeresfordTOOTH TISSUES: Pulp
PULP
DENTINE
ENAMEL
CEMENTUM
PERIODONTAL
LIGAMENT/PDL
ALVEOLARBONE
GINGIVA
DENTAL PULP: Functions
Service tissue keeping its Odontoblasts alivefor slow defensive responses in the dentine
Providing antimicrobial defense for thedentine and itself
Providing sensory feedback from the dentine,but for what purposes?
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PULP
DENTINE
ENAMEL
CEMENTUM
PERIODONTALLIGAMENT/PDL
ALVEOLAR BONE
GINGIVA
Service tissue keeping its Odontoblasts alive for slowdefensive responses in the dentine
Providing antimicrobial defense for the dentine and itself
Providing sensory feedback from the dentine, but forwhat purposes?
WABeresfordTOOTH TISSUES: Pulp & its roles
PULP CHAMBER
CORONAL PULP HORN
ACCESSORYCANAL
ROOT CANAL
APICAL FORAMEN
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PULP REGIONS
ODONTOBLASTLAYER
PULP PROPER/PULP CORE
Cell-poorZONE OF WEIL- peripheral pulp
PULP ELEMENTS - Mucoid connective tissue
MATRIX -Ground substanceReticular fibers
Collagen Ifibers Elastic fibers
Blood vesselsNervesLymphatics
CELLS -
OdontoblastsFibroblastsMacrophagesMast cellsLeukocytes
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PULP INNERVATION
Nerves: sensory (V) to
PULP
ODONTOBLASTS
DENTINAL TUBULES
Blood vessels
Nerves:
autonomic
12 3
1
2
3
Sub-odontoblastic plexusin cell-poor zone of Weil
PULP ELEMENTS - Mucoid connective tissue
MATRIX - Groundsubstance Reticularfibers Collagen I fibersElastic fibers
Blood vesselsNervesLymphatics
CELLS -OdontoblastsFibroblasts
MacrophagesMast cellsLeukocytes
& Denticles & Fibrosis with aging
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PULP
DENTICLES/ PULP STONES
Hard mineralized bodies found inthe pulp or the dentine
TWO TYPES:
1 TRUE - constructed of dentine
by ectopic odontoblasts & showingdentinal tubules
2 FALSE - mineralized connective
tissue, etc, (not made of dentine)
Both may show layering/lamellar patterns
from incremental growth
P
ULP
DENTICLES/ PULP STONES:further classification by place
Hard mineralized bodies found in the pulpor the dentine
THREE SUBTYPES:
1 FREE - in the pulp
2 IMBEDDED - enclosed in thedentine as this has slowly grown
inwards
3 ATTACHED - partly imbedded
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TOOTH GERM: Pulp development
DENTAL LAMINA
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
DENTAL ORGAN
MESENCHYME
ALVEOLAR BONE
TOOTH TISSUES: Sources
DENTAL LAMINA
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
DENTAL ORGAN
MESENCHYME
ALVEOLAR BONE
PULP
DENTINE
ENAMEL
CEMENTUM
PDL
A BONE
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TOOTH TISSUES: Sources
DENTAL LAMINA
DENTAL PAPILLA
mesenchyme
DENTAL SAC/FOLLICLE
DENTAL ORGAN
ALVEOLAR BONE
PULP
DENTINE
ENAMEL
CEMENTUM
PDL
A BONE
TOOTH
Crest
Ameloblasts
Odontoblasts
CT cells
Cementoblasts
Fibroblasts
Osteoblasts & clasts
TOOTH TISSUES: Sources
DENTAL LAMINA
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
DENTAL ORGAN
ALVEOLAR BONE
PULP
DENTINE
ENAMEL
CEMENTUM
PDL
SUPPORTINGBONE
TOOTH
LAMINA DURA
Plate
Spongy bone
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TOOTH GERM
DENTAL LAMINA
Outer dental epithelium
Stellate reticulum
Inner dental epithelium
Stratum intermedium
DENTAL PAPILLA
DENTAL SAC/FOLLICLE
Vessels Nerves
HERTWIGSROOTSHEATHgrows tolengthen root
PULPdifferentiates
Epithelial diaphragm
FURTHER ROOT FORMATION
Odontoblast recruitment site
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EXTRACELLULAR MOLECULAR INTERACTIONS 1
Further assemblyof the molecules to make larger &eventually visible structures, such as fibrils
Modificationof the molecules, e.g., cross-linking, to make
them resistant to digestion
Deliberate breakdownof the molecules by the forming cellsfor turnover and renewal, by proteases & other enzymesControlled breakdown, with more synthesis & assembly,provides for remodeling & adaptation of ECM, e.g., to
heavier load in tendon or cartilage
Some of these enzymes, e.g. collagenase, include a zinc atom& require Ca2+ to work - hence Matrix Metalloproteinases, e.g.MMP-3
ECM MOLECULAR INTERACTIONS - Pathology 1
The inhibitorsof these enzymes go under the abbreviationTIMPs- Tissue Inhibitors of MMPs; & are also made byfibroblasts & other matrix-influencing cells
Some of these enzymes, e.g. collagenase, include a zinc
atom & require Ca2+ to work - hence MatrixMetalloproteinases, e.g. MMP-3
Unintended degradationby enzymes released from cells,e.g., leukocytes, engaged in defensive reactions.
ECM is the battlegroundfor defenses initially targeted atmicroorganisms.
--itises occur throughout the body, & are real hazards tocomfort & life, e.g., endocarditis weakens & distorts heartvalves
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Unwanted degradationby bystander inclusion in cytokinesignaling pathways of defensive cells
M Lymphocytes of inner joint synoviumIL-1
Articularchondrocytes
IL-1Joint cartilage cells alsorespond to the signal:enzymes enzyme inhibitorsproteoglycans
= an inappropriate response causing cartilage matrixdestruction - ARTHRITIS
ECM MOLECULAR INTERACTIONS - Pathology 2
Unwanted degradationby bystander inclusion in cytokinesignaling pathways of defensive cells
M Lymphocytes of inner joint synoviumIL-1
Articularchondrocytes
IL-1
Joint cartilage cells alsorespond to the signal:enzymes enzyme inhibitors
proteoglycans
= an inappropriate response causing cartilage matrix
destruction - ARTHRITIS
ECM MOLECULAR INTERACTIONS - Pathology 2
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Unwanted degradationby:
microbes trying to colonize, e.g., using bacterial hyaluronidase
to liquify ground substance
metastasizing cancer cells breaking through basal laminae
& connective tissues
Unwanted synthesis - the formation of excess collagen,clogging organs with delicate blood-cell relations.
Cytokines released by activated macrophages triggersynthesis in fibroblasts, causing cirrhosisin the liver and
fibrosisin kidney, lung, marrow, etc
ECM MOLECULAR INTERACTIONS - Pathology 3
Bad assembly - genetically defective fibrillin makes aninadequate scaffold for elastin deposition weak aorta,slack connective tissues, etc, of Marfans syndrome
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TOOTH
LIP
LIP
HARD PALATE SOFT PALATE
TONGUE
ORAL STRUCTURES Sagittal view
SALIVARY GLANDS
ALVEOLAR BONE+ CHEEK WABeresford
ORAL LINING - oral mucosa of stratifiedsquamous epithelium + lamina propria
LIP & CHEEK
TONGUE
MANDIBLE & MAXILLA Alveolar bone
SALIVARY GLANDS - major & minor
HARD PALATE
SOFT PALATE
ORAL STRUCTURES
TOOTH
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SALIVARY GLANDS - major & minor
Parotid
Sub-lingual
Sub-mandibular
MINOR
Labial
Buccal
Lingual
Palatal
serous
mixed - SERO-mucous
mixed - MUCO-serous
mucous
mucous
serous, mucous & mixed
mucous
MUCOUS TUBULE
MYOEPITHELIAL CELL
SEROUS DEMI-LUNE
BL
SEROUS ALVEOLUS
MUCOUS TUBULE
with
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PROTECTION
SALIVA - Functions
ALIMENTARYFood approval: taste, texture
Mastication
Swallowing
Digestion
OTHER Vocalization
Excretion ?
Spit as a tool
EpitheliallubricationAnti-microbial materials
For tooth: Rinsing BufferingMineralization Pellicle coat
PROTECTION
SALIVA - Functions
ALIMENTARY Food approval: taste, texture
Mastication
SwallowingDigestion
OTHER Vocalization
Excretion ?
Spit as a tool
EpitheliallubricationAnti-microbial materials
For tooth: Rinsing BufferingMineralization Pellicle coat
MATERIALSWaterMucins (glycoproteins)
Antibodies IgAsLysozyme DefensinsIons - bufferingIons - tooth mineralAmylaseIodine
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CleaningShowing disapproval
SALIVA - Functions & means
Food approval: taste, texture
Mastication
Swallowing
Digestion
Vocalization
Excretion ?
Spit as a tool
Epithelial lubricationAnti-microbial materials
For tooth: Rinsing Buffering MineralizationPellicle coat Water) Ions - buffering Ions - tooth mineral
Antibodies IgAs Lysozyme DefensinsWater Mucins
Touch & taste receptors & nerves
Water Mucins
Amylase
Iodine
Water
Water Mucins Mucous glands concentratedat back of mouth
PANCREATIC DUCTS: model for salivaryDuodenalpapilla
Exocrine acini
Lobule
}Principal duct
Interlobular duct
Intralobular ducts
Intercalated ductsSalivary gland is more compact,has denser CT, & no islets
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SALIVARY DUCTS
Principal duct
Interlobular duct
Intralobular duct
Intercalated duct
SALIVARY DUCTS: Epithelia
Principal duct
Interlobular duct
Intralobular duct
Intercalated duct
Stratified cuboidal /columnar
Simple cuboidal/columnar
Simple cuboidal
Low cuboidal/squamous
Accompanied by CT
Accompanied by CT
Be prepared for pseudo-strat & mixed types
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SALIVARY DUCTS: Synonyms
Principal duct
Interlobular duct
Intralobular duct
Intercalated duct
Whartons, Stensens, etc
Excretory (drain-pipe)
Secretory/Striated (from basalmitochondria and membraneinfoldings for ion transport)
Classifications by site versusfunction
Intercalated (in between)
Eosinophilic
PAROTID GLAND
SEROUS ACINi
INTRA LOBULARDUCT
INTERCALATED DUCT
INTER LOBULAR DUCT
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SUBMANDIBULAR GLAND
SEROUS ACINi
INTRA LOBULARDUCT
INTER LOBULAR DUCTA FEW MIXEDMUCOUSTUBULES
SEROUSdemilune
SUBLINGUAL GLAND
INTER LOBULAR DUCT
MIXEDMUCOUSTUBULES
SEROUSdemilune
PUREMUCOUSTUBULE
INTRA LOBULAR DUCT(few & not striated)
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DUCT SYSTEM complex tributaries
Principal duct
Interlobularducts
Intralobular ducts
Intercalated ducts
The scheme does not dojustice to the length andbranching of a duct sytem for alarge compound gland. Thinkstreams entering Deckers creek all theway to the mouth of the Mississippi.
So one term, e.g,intralobular duct, coversa variety of widths and
even epithelial types,and there will betransitional forms, andstrange section cuts.
SALIVARY GLANDS - major & minor
MINOR
Labial
Buccal
Lingual
Palatal
mucous
mucous
serous, mucous & mixed
mucous
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Tongue papillae
Muscular core
Nerve
Sub-lingual gland
Duct
Blood vessels
Connectivetissue
TONGUE
Lingual gland
TONGUE - dorsum
TONSILS
CIRCUMVALLATEPAPILLA
FILIFORM PAPILLAE
FUNGIFORM PAPILLA
Taste bud
Trench
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TONGUE - dorsumTONSILS
CIRCUMVALLATE PAPILLA
FILIFORM PAPILLAE
FUNGIFORM PAPILLA
Neither associatedwith glands
von Ebnersserous glandsfor taste
Webers posterior mucousglands to flush out tonsils
Blandin/Nuhnsmixed anteriorlingual glands
LIPRED MARGINVERMILION BORDER
HAIRY SKIN
MUSCLE
LABIAL MUCOSAthick strat squam ep
LABIALGLANDmucous
RED MARGINkeratin thins awayno follicles or glands
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CHEEK
HAIRY SKIN
NO RED MARGIN
BUCCAL MUCOSAthick strat squam ep
BUCCAL GLANDmucous
MUSCLE
ADIPOSE TISSUE
HARD PALATE: Cross-section
PALATE BONE
RAPHE
ADIPOSE CT - anteriorMUCOUS GLANDS -posterior
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GUT MOTOR INNERVATION
with H & E staining, the only neural elements seen are the neuronbodies & characteristic nuclei. The plexuses of fibers are unseen.
Unmyelinated autonomic nerve
muscle
submucosa
Auerbachs myenteric plexus
Meissners submucosal plexus Rare neuron bodies of
plexus
Clumped
neurons of Asplexus
neurons are multipolar, with dendrites!
SALIVARY GLAND INNERVATION
with H & E staining, the only neural elements seen are the few neuronbodies & characteristic nuclei. The plexuses of fibersto acinar cells,myoepithelial cells, ducts, & vessels are unseen.
Unmyelinated autonomic nerve
Clumped neuronsof minor ganglia
Parasympathetic neurons are multipolar, with dendrites!
Parasympathetic post-gangionic fibers
Sympathetic post-gangionic fibers
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TEMPOROMANDIBULAR JOINT/ TMJ
One jaw has twoTMJs * *
The joint is a freely moveablesynovial jointwith a cavity
Each joint is between thecondyleof the mandible andthe temporal boneof the skull
There are actually two cavitiesbecauseof an intervening cushioning disc
There are other differencesfrom thetypical synovial joint
CC
WABeresford
CONDYLE
CORONOID PROCESS
RAMUS
BODY
MENTAL SYMPHYSIS
PARTS OF THE MANDIBLE
ALVEOLAR RIDGE
TEETHCONDYLAR
PROCESS
ANGLE
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EXT AUD MEATUS
RELATED SKULL FEATURES
FOSSAARTICULARTUBERCLE
ZYGOMAin outline
STYLOID PROCESS
Lateral pterygoidplate (deep)
Why so much ramus & coronoid process?
CORONOID PROCESS
RAMUS
BODY
ATTACHMENT SURFACE FORMASTICATORY MUSCLES
These muscles enclose, define & stabilize the TMJ:And capsules & ligaments play a role
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Lateral ligament
FIBROUS ATTACHMENTS TO SKULL
Stylomandibularligament
Joint capsule
Sphenomandibularligament inserts onmedial side (lingula)
DISLOCATION beyond art. tubercle
These attachmentsallow an anteriordislocationof themandible,