merchant review
TRANSCRIPT
8/2/2019 Merchant Review
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tooth developmentenamel
dentinroot formationcementumperiodontal ligamenttooth eruption
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Vestibule
Developing teeth
Successional lamina (permanent teeth primordia)
(Lateral lamina)
Vestibular lamina
Primary lamina* Oral epithelium
Extensional lamina
( primary lamina)
(dental arch)
*
future ameloblasts
future odontoblasts(neural crest)
inner enamel epithelium
*apoptosis to form vestibule
ENAMEL
ORGAN
* lamina = epithelial ingrowth
molars4 mo (f) 4 yrs 5 yrs
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1) Oral epithelium:-ameloblasts (enamel)
Oral mesenchyme*
2) dental papilla:-odontoblasts (dentin)-pulp cells
3) dental follicle:-cementoblasts (cementum)-fibroblasts
(periodondal ligament)-osteoblasts(alveolar bone)
1
3
2
Bud Stage:
* collagenous regionsweek 6
Oral epithelium Primary
dentallamina
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What is the tissuebetwen the arrows?
Primary dental lamina
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What is the cell layerat the arrow?
ENamel organ cap stage.
Inner enamel epithelium
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Not ameloblast; really just an
inner enamel epithelium
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Is this a primary tooth?
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DF = Dental follicle:-cementum (cementoblasts) -periodontal ligament
(fibroblasts) -alveolar bone (osteoblasts)
epithelial pearls(of Serres)
DP = Dental papilla:-crown dentin-root dentin
DF DP
Gubernacular cord
Successional lamina
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Bell Stage:
successionallamina
membranapreformativa
undifferentiatedenamel organ
vestibular
laminaprimarydentallamina
tongue
*
stellatereticulum
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odontoblasts
ameloblasts
enamel
dentin
*
**
*
Tomes’ processTomes’ fiber
**Enamel deposition will occur ONLY on a dentin substrate**
Deposition of mineralized tissues:
Aprismatic
Dentin causes
differentiationof ameloblasts
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*
Green asteriskis labeling:
a) enamel matrixb) enamelc) neither
Enamel itself will only appear when crown is
completely formed.
This is just an artifact.
You don't see enamel matrix because you only see
dentin in this view
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What stage of toothdevelopment isdepicted?
(matrix)Check for deposition of mineralized tissue: this will mean
appositional stage
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odontoblasts
outer enamelepithelium
stratumintermedium
stellate reticulum
enamelmatrix
inner enamel
epithelium(ameloblasts)
dentin
predentin
dentalpapilla
differentiatedameloblast
Thickest region will be on top.
Thickest dentin and enamel
Undifferentiated ameloblast vs
differentiated ameloblast.
Morphology changes
Apical end of cell makes enamel.
Polarity and nuclei shifts.
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pre-ameloblasts
ameloblasts
membrana
preformativa
ameloblasts & stratum
intermedium cells are
perpendicular to each
other
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enamel rod(prism)
DEJ
Tomes’process enamel crystals
+water, proteins(“enamel matrix”)
Amelogenesis
. .... ..dentin
aprismaticenamel
temporal progression
maturationstages
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matrix
The arrows are pointing toward whatstructures? Tome's processes ?
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Tomes’ processes
enamel crystals
enamel matrix
matrix
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Enamel crystals
Enamel crystals growin length
(during enameldeposition phase)
amelogeninassembly
small nanospheres(hydrophilic)
removal ofhydrophilic tails
(enamelysin)
large nanospheres(hydrophobic)
Ca2+
Enamel crystals growin width
(during maturation phase)
enamelinnucleation?
enamel serineprotease
enamelin
enamelin
Tome’sprocess
Once crystal formation happens,
blue crystals get coated by
amelogenins.
Amelogenin is removed during
maturation
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Enamel rods (prisms):
hydroxyapatitecrystals
AA
T
enamel proteins,protein fragments(between crystalites)
TB
GJ
secretory vesicles(protein secretion)
stratumintermedium
(tail)enamel crystalites
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aprismatic enamel(20-100µ m) Prismatic enamel:
-results from loss ofTomes' process
-all crystalites ⊥ to surface
-highly mineralized-must be removed tocreate "tags" forbonding procedures
prismatic enamel
prismatic enamelDEJ
oralcavity
Prismatic vs. aprismatic enamel:
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Enamel spindles:
DEJ
-extensions of odontoblast
processes (dentin tubules)-most abundant at cusp~5-50 µm
D
E
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DEJ
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The structures at thearrows are?
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Enamel
tuftsDEJ
hypomineralized,rich in the acidprotein ‘tuftelin’
DEJ
ES
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The arrow is pointing to what structure? Howcould you test your answer?
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X
= ameloblast
Enamel lamellae-hypomineralized (mineralization failure)
-resemble enamel matrix -protein-rich-prone to develop cracks
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The lines that have the same orientation as thearrows represent what structures?
Rods are running in direction
of arrows
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ameloblast
Tomes’ process
Enamel crossstriations
(short period,diurnal increments)
2.5 –6 um
Daily incremental growth line
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Striae of Retzius
(long period)
1
234567
Weekly growth intervals
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Striae of Retzius (long period)
-weekly reduced rate of secretion-unequal termination of growth cycle
(delayed interrod termination)-crystal orientation is disrupted
interrod
rod Striae
Striae
Striae
321
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Neonatal lines
Did this tooth begin mineralization inthe 1st, 2nd or 3rd trimester?
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The arrows represents what structures?
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Perikymata“imbrication lines of Pickerill”
7-10 days
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The arrows depict ___ - __ __?
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parazones(light bands)
diazones(dark bands)
50 µm
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Hunter-Schreger lines
enamelsurface
parazone
diazone
parazone
pulpcavity DEJ
dentin
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Gnarled enamel
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Which successional tooth is older?
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Which successional tooth is older?Does enamel maturation HAVE to
occur prior to eruption?
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Enamel crystals
Enamel crystals growin length
(during enameldeposition phase)
amelogeninassembly
small nanospheres
(hydrophilic)
removal ofhydrophilic tails
(enamelysin)
large nanospheres(hydrophobic)
Ca2+
Enamel crystals growin width
(during maturation phase)
enamelinnucleation?
enamel serineprotease
enamelin
enamelin
Tome’sprocess
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ameloblasts
reduced enamel
epithelium
“basal lamina” orprimary cuticle
-increase in crystal thickness (& consequent reduction in intercrystalline space)
(1.5 nm 25nm)-secretion of calcium & phosphate ions-removal of water and protein (mostly amelogenin, squeezed to surface by
expanding crystals)-final protein content:
enamel pitsamelogenin (90%)enamelintuftelinameloblastin
(sheathlin)
(10%) 1-2% ofenamel
H2O, protein minerals
DEJ .. .... ..
aprismaticenamel
synthesis maturation
secretory & ruffledborder stages
aprismaticenamel
Enamelmaturation:
enamel rod(30% mineralized)
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Dentin Enamel
Formed throughout life Formed prior to eruptionContains nerves No nerves
Contains cell processes AcellularContains collagens Contains enamel proteinsSmall crystals Large crystalsOne step mineralization Two step mineralization
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odontoblasts
dentin
predentin
Dentin deposition:
dentinal tubules(Tomes’ fibers)
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nerveaxons
microtubules
intertubular
intra(peri)tubular
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Intertubular dentin
Peritubular dentin(intratubular,
sheath of Neuman)
hypermineralized(no collagen)
ns
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A What type of dentin isdepicted at "A"?
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Demarcation linePrimary dentin(circumpulpal)
CP
3o
2o
Pulpcavity
mantle dentin
enamel
(a.k.a. reactionary, restorative,reparative, response)
tubules if present, very irregular
Dentin typesa) branchingb) less mineralized
c) collagen⊥
to DEJ
TGL
1o
CP 1o
2o
CP
Mantle:
Secondarydentin
(formedafterroot
completion)
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circumpulpaldentin
mantledentin
enamel
Polarized light
mantle
dentin20-150 uMthick
enamel
circumpulpaldentinmantle dentin found only
in crown
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Demarcation linePrimary dentin(circumpulpal)
Secondarydentin
(formedafterroot
completion)
CP
3o
2o
mantle dentin
enamel
(a.k.a. reactionary, restorative,reparative, response)
tubules if present, very irregular
Dentin typesa) branchingb) less mineralized
c) collagen⊥
to DEJ
TGL
1o
CP 1o
2o
CP
Mantle:
Pulpcavity
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What type of dentin isdepicted at the arrow?
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1o & 2o - formed by odontoblasts
3o - formed by newly recruited
mesenchyme (PULP responds to insult)
Potential fate of 1o & 2o dentin:Dead tracts - empty, sealed tubulesSclerotic - fully mineralized tubules
(excess peritubular dentin)
dead tracts
scleroticdentin
3o
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Translucent dentin
Physiological-increases linearly with age (use in forensics)-begins to form at root apex-physically similar to sclerotic dentine
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Incremental growth lines (diurnal) of Von Ebner(short period lines)
tubules
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Lines of Owen(pronounced Andresen line)
Linesof
Owen
Incremental growth lines (weekly) ofAndresen (long period lines)
~weekly deposition-duration equivalent to striae
of Retzius in enamel*-cause unknown
~1 wk
secondarycurvature *implies similar cause, but unknown
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The arrows represent......?
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Interglobular dentin
enamel
Tubule direction isunaffected - but they
lack peri (intra)tubular dentin(hypomineralized)
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Interglobular dentin
enamel
Tubule direction isunaffected - but they
lack peri (intra)tubular dentin(hypomineralized)
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24 hourspredentin
dentin
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Globular mineralization
collagen +dentinphosphoprotein
(DPP)
calcospherite“globularmineralization”
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Globular mineralization
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interglobular dentin(hypomineralized)
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These holesrepresent whatstructures?
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The region between thearrows is called_______?
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hyaline layer(mantle equivalent)
Tomes' granularlayer
Root dentin
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Tomes' granular layer
highly branchedodontoblast tubules
“granules”
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Development of root& supporting structures
-root proper-cementum-periodontal ligament-pulp cavity
apical foramen
-root growth commencesonly after crown completion
-root growth initiation
coincides with axialeruption phase
-root maturation may takeup to 3 years
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Identify the structures labeled “A”(hint: they are cytokeratin positive)
C t /d ti
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mesenchymalcells from follicle
(presumptive cementoblasts)
Dentin
Enamel
Intermediate
cementum
rootdentin
intermediatecementum
cellularcementum
CEFC)
cementocyte
**Cementum deposition willoccur ONLY on a dentin substrate**
Hertwig’s root sheath
Cementum/dentinformation:
CEFC=cellular extrinsic
fiber cementum
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Hertwig’sRootSheath
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Hertwig’sRootSheath
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Hertwig’sRootSheath
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Hertwig’sRootSheath
root dentin – pulp mesenchyme
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Hertwig’sRootSheathintermediate cementum – epithelial product
root dentin – pulp mesenchyme
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Hertwig’sRootSheathintermediate cementum – epithelial product
root dentin – pulp mesenchyme
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Hertwig’sRootSheath
pre-cementoblasts
intermediate cementum – epithelial productroot dentin – pulp mesenchyme
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Hertwig’sRootSheath
pre-cementoblasts
intermediate cementum – epithelial productroot dentin – pulp mesenchyme
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Hertwig’sRootSheath
pre-cementoblasts
intermediate cementum – epithelial productcementum – follicular mesenchyme
root dentin – pulp mesenchyme
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Hertwig’sRootSheath
pre-cementoblasts
intermediate cementum – epithelial productroot dentin – pulp mesenchyme
cementum – follicular mesenchyme
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Hertwig’sRootSheath
pre-cementoblasts
intermediate cementum – epithelial productroot dentin – pulp mesenchyme
cementum – follicular mesenchyme
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Hertwig’sRootSheath
pre-cementoblasts
intermediate cementum – epithelial productroot dentin – pulp mesenchyme
cementum – follicular mesenchyme
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Identify the tissueat the arrow
(be specific)
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canaliculi
cementocyte(lacuna)
PL
incrementallines ofSalter
cementoblasts
appositionalgrowth
Cellular & acellularcementum
-avascular-canaliculi not interconnected-forms anchoring substrate for PL
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Repaired cementum(cellular intrinsicfiber cementum)
Cementum formation
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epithelial restsof Malassez
HRS
Cementum
Dentin
cementicle(attached)
Cementum formationaberrations:
Hertwig’s root
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root sheath discontinuity
Cementum
Exposed
rootdentin
Enamel
(alternatively, mayform enamel pearl)
*
*
enamelpearl
Hertwig s rootsheath anomalies:
root sheath adhesion
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NC
Hertwig’sRootsheath
X
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NC
Hertwig’sRootsheath
X
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NC
Hertwig’sRootsheath
X
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NC
Hertwig’sRootsheath
X
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NC
Hertwig’sRootsheath
X
root canal
accessory root canal
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What tissue waspresent at the
* in life?
*
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loss of lamina duradue to osteosarcoma
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Identify the tissuebetween the arrows
(Is it demineralizedor ground?)
Periodontal ligament:
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r n g m n-attachment (usu. bone cementum)-cushioning-tooth positioning:
eruptiondrift
-source of repair cells-mechanoreceptors
pulp
cells: fibroblastscementoblastscementoclastsosteoblastsosteoclasts
epithelial cellsdefenseneural
DF
Alveolar bone(L. alveus: hollow sac, cavity)
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interstitial
“spaces”
0.2 - 0.4 mm
1) PL collagen - high turnover rate
2) PL fibroblasts- intercellular connections- cilia (microtubules = 9+0)
3) contains cells for synthesis, repair,defense etc.
4) contains “anti-calcification” properties-hyaluronidase treatment leads to
mineralization
D
C
B
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cortical bonespongy bone
alveolar bone proper(lamina durabundle bone)
Principalfibers
5 µ mprincipal fiber
supporting bone:
1) apical2) oblique3) horizontal4) alveolar crest5) transseptal 6) gingival
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bone
rootdentin
sharpey’sfibers
PL fibers
Oxytalan fibers
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Oxytalan fibers(microfibril component of elastic fibers)
Pulp
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Pulp
cell-rich zone
(progenitorodontoblasts)
nerve axon(unmyelinated)
odontoblastprocess
cell-free zone-artifact?-reduced in root
odontogenic zone:
*
*columnar in crown;cuboidal in root pulp
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generalsensory
autonomic(sympathetic)
-fibroblasts (col I and III)-nerve cell axons-schwann cells-endothelial cells-inflammatory cells-macrophages-mesenchymal progenitor cells
lymphatic
vein &
artery
unmyelinatedhere
Pulp denticles
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Pulp dent clesPulp stones (false denticles)
false pulp stone(concentric)
true pulp stone(denticle)
Eruption &
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Eruption &Shedding
1) tooth movements
2) resorption
3) eruption
Tooth movements:
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1) Preeruptive:
-up to crown completion(prior to initiation of root formation)-movement due to permanent tooth growth, jaw growth-associated with alveolar bone remodeling (as are prefunctional
& functional stages)
a) Tooth body movementresorption synthesis
b) Relative movement (relative positioning)
c) Eccentric movement
2) Eruptive:
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2) Eruptive:-begins during initiation of root formation-secretory phase of amelogenesis
has ended (A)-fusion of reduced enamel
epithelium and oral epithelium (B,C)-tooth emergence (E)-intraoral movement until clinical
contact with opposing crown (F,G)
3) Functional:
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)-root completion (apical foramen narrows, tooth reaches occlusion) (A)
1-1.5 yrs for primary teeth2-3 yrs for permanent teeth
-final organization of PL fibers is achieved-movement to compensate for enamel wear (B)-movement to compensate for tooth wear/loss (C, D)
attrition ofincisive enamel
compensatorythickeningof cementum
A B
mesiallabial
trans-septal
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mesial
mesial
distal
distal
buccal
lingual (palatal)
lingual
(palatal)
vertical(super-eruption)
mesial drift
C
D
pfibers
Forces driving tooth eruption:
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Forces driving tooth eruption:
1) Pulpal pressure andpulpal growth
2) Traction by periodontalfibers and fibroblasts
3) Root elongation
4) alveolar boneremodeling
Factors affecting eruption
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local:
-overcrowding (supernumary teeth)-tooth impaction-ankylosis
systemic:
-osteopetrosis (osteoclast disruption)-Ca2+ disruption (Rickets, parathyroidproblems etc.)
environmental:
mesiodens
impacted molar
ankylosed tooth
g p
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The cavities depicted at "A" are madeby________? (be specific) What are theycalled?
A
Resorption/shedding of primary tooth:
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p g f p m y
D
D
odontoclasts inHowship’s lacunae
Dentin
Primary tooth shedding:-loss of root (“mineraloclast” resorption)
-concomitant loss of PL fibers -loss of bone-mastication forces
Resorptive cells (mineraloclasts):
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odontoclast (dentin resorption)
ameloclast (enamel resorption)cementoclast (cementum resorption)osteoclast (bone resorption)
sorpt c s (m n ra oc asts)
multinucleate cellsderived from fusionof monocyte-macrophagecells
enamel: 96% mineralizeddentin: 70% mineralizedbone: 65% mineralizedcementum: 60% mineralized
Howship’s lacunae
Soft tissues (periodontal
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Soft tissues (periodontalligament) also becomes
remodelled in resorptionzone
What structure occupies these foramina
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What structure occupies these foraminain life? Is the dentition present primary
or secondary?
Gubernacular
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Gubernacularcord in canal
Gubernacular corddoes not "pull" toothinto oral cavity
(surgical removal leads to
ossification ofgubernacular canalbut the tooth eruptsnonetheless)
Gubernacular cord:(L rudder)
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(L. rudder)
-remnant of dental lamina
-acquires ECM coating-prevents bone formation
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The cellular tissue
between the arrowsis called the ______?
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Formation of junctional epithelium & 1o
cuticle
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enamel
reduced enamelepithelium
dentin
Formation of junctional epithelium & 1o
cuticle
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enamel
reduced enamelepithelium
primarycuticle
dentindentin
outer enamel
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developmental(primary)
cuticle
reduced enamel
epithelium
Nasmyth’s
membrane
enamel
mepithelium
inner enamelepithelium
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e n a m e l s p a c e
gingivalepithelium
REE
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e n a m e l s p a c e
gingivalepithelium
REE
Attachment epithelium: mature tooth
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dentinenamel space
gingival sulcus
gingiva
epthelialattachment(junctionalepithelium)
enamel surfacei d lli l
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plaque
enamel surfaceabove & belowgingival sulcus
acquired pellicle