the most important slides of oral histo lab for the 1st 7 labs

8/2/2019 the Most Important Slides of Oral Histo Lab for the 1st 7 Labs

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Slide lab review

Tahany M. Abu Al - Teen

Mohamed Tawalbe


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Collection of the most important slides in the firstCollection of the most important slides in the firstCollection of the most important slides in the firstCollection of the most important slides in the first 7777labs of oral histology lablabs of oral histology lablabs of oral histology lablabs of oral histology lab

1 Primary epithelial band2 Vestibular lamina3 Dental lamina4 Early tooth formation (Bud stage)5 Condensed ectomesenchymal tissue

*** How to differentiate btwn dental lamina and vestibularlamina in any section??

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Vestibular laminaVestibular laminaVestibular laminaVestibular laminaDental laminaDental laminaDental laminaDental laminaGoes buccallyGoes lingually

Cells have spaces btwn themtill the whole structure

becomes a space

Has swelling (condensation)at it's end where the cells are

packed together

Ectomesenchymal tissuearound vestibular lamina

doesn't condense

Surrounded by condensedectomesenchymal tissue

Doesn't invaginateInvaginate into condensedectomesenchymal tissue

(Primary epithelial band = PEB, Dental lamina = DL,Vestibular lamina = VL)

** Primary epithelial band = invagination of oral epitheliuminto underlying condensed ectomesenchymal tissue and itdivides there into dental and vestibular laminea

** PEB and DL and VL all these exist in condensed

ectomesenchymal tissue

** Invagination of DL into condensed ectomesenchymaltissue is responsible for teeth formation and it passesthrough 3 stages (based on the shape of the invagination)and these stages are :

1. Bud stage 2. Cap stage 3. Bell stage

** In this slide the invagination looks like a bud that's why we

call this stage of teeth formation the " Bud stage "

SO >> the bud, cap and bell all these come from DL and theydescribe the way in which crownscrownscrownscrowns (nt roots) are formed


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1 DL2 The cells at the end of DL start to pack together andprepare themselves to invaginate into ectomesenchymaltissue to start teeth formation

3 The ectomesenchymal tissue starts to condense aroundthe end of DL

No invagination has appeared yet

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BudBudBudBudStagStagStagStag


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This slide represents the "Bud Stage" coz the invaginationlooks like a bud

** This slide represents the "Cap stage" coz here theinvagination looks like a cap

1 EEE2 SR3 IEE

4

Dental papilla5 Enamel Knot (transient structure in the center of IEE thatbulges into dental papilla)

CapCapCapCapStageStageStageStage

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1 SR2 SI3mature IEE (preameloblast)

4 undifferentiated ectomesenchymal cells (are going tobecome odontoblasts)

** At which stage this slide is?? Notice1. The presence of SI (2-3 layers of cells over IEE)2. IEE cells are mature and about to differentiate intoameloblasts

3. The ectomesenchymal cells aren't differentiated yet4. NO hard tissue formation has started yet

All these tell that this tooth is in the "E"E"E"Earlyarlyarlyarly BBBBellellellell SSSStagetagetagetage"""" and itisn't in the cap stage coz in cap stage we don't have SI andthe IEE cells are slightly columnar, and it isn't in the late bellstage also coz we don't have any hard tissue formation and(dentine + enamel) producing cells aren't mature yet

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1 EEE2 Enamel formation3 Dentine formation4 SR

5 IEE6 Cervical loop7 Area where there's NO hard tissue formation8 Dental follicle9 Dental papilla

** At which stage this slide is?? It is at "Late Bell Stage""Late Bell Stage""Late Bell Stage""Late Bell Stage" coz we have hard tissue formation

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1 EEE2 SR3 Enamel

4 Dentine5 Dental pulp

This tooth has 2 cusps

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Notice these lines that are running obliquely across theprisms of enamel these are the long incremental lines orenamel striae (nt all of them reach the surface)

When enamel striae appear like lines running obliquelyacross enamel prisms then this is a longitudinal sectionacross enamel


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The previous slide represents Enamel lamella than runsthrough the entire thickness of enamel

This slide represents two structures exist at EDJ and theseare EEEEnamel tuftsnamel tuftsnamel tuftsnamel tufts and EEEEnamel spindlesnamel spindlesnamel spindlesnamel spindles

** How to differentiate btwn them in a histological section??

** Enamel spindles = are of unequal length and aren't backedtogether and thicker than enamel tufts and they are believedto be odontoblastic processes

** Enamel tufts = resemble tuft of grass, are approximately ofequal length, very close to each other and backed togetherand thinner than enamel spindles

EnamelEnamelEnamelEnamelspindlesspindlesspindlesspindlesEnamel

tufts

ScallopedScallopedScallopedScalloped pattern ofpattern ofpattern ofpattern of

EDJEDJEDJEDJ


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The encircled structure represents enamel prisms


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The previous slide represents enamel striae but this is across section of enamel that's why they appearcircumpulpally running

The encircled structure here shows dead tracts of dentine(dead odontoblastic processes)

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1 SR2 SI3 Ameloblasts4 Enamel

The encircled structures are Tome's processes

** At which stage of amelogenesis this stage is??

Secretory stage

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1 undifferentiated ectomesenchymal cells (dental papilla)2 Odontoblast3 Dentine4 Enamel

5 Ameloblast6 Tome's process7 SI8 SR

A = Granular layer of Tome's

B = Cementum

C = Hyaline layer (appears as space)Arrow head = circumpulpal dentine

Is it coronal or root dentine??

Root dentine (based on the type of the layers)

PDLPDLPDLPDL


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A = Peritubular Dentine (around dentinal tubules)

B = Intertubular Dentine (btwn neighboring dentinal tubules)

Arrow head = Dentinal tubules

MineralizedMineralizedMineralizedMineralizedcollagenouscollagenouscollagenouscollagenous

matrixmatrixmatrixmatrix


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The previous slides represent dentinal tubules that areimpeded in mineralized collagenous matrix

Vital dentinal tubules contain odontoblastic processes anddentinal fluid

Unvital dentinal tubules are called dead tracts (cozodontoblastic processes inside them become dead)

Here dentinal tubules appear as real tubules coz this is alongitudinal section across dentine


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In the previous slide dentinal tubules appear as circles cozthis is a cross section across dentine

Notice here odontoblastic processes inside dentinal tubules

(dark pink color)


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In the previous slide notice the amount of branching ofdentinal tubules and odontoblastic processes inside them

Which layer of dentine is this??

Mantle dentine (1st

layer of dentine in the crown)

How did I know?? the presence of a jxn which is scalloped in pattern and it isthe one that separate btwn enamel and dentine that's whythis layer of dentine is in the crown and because it has toomany branching it is mantle dentine

Notice also that in mantle dentine collagen fibers are parallel

to EDJ

A = Circumpulpal dentine in the crown

B = Circumpulpal dentine in the root

In both (crown and root) circumpulpal dentine is runningcircumpulpally (around the pulp)

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Arrow head = Predentine

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A = Shreger line

B = contour lines of Owen

C = long period incremental lines of dentine (don't think thatthese are dead tracts coz as you notice they are of unequallength and don't extend through the entire thickness ofdentine)

This slide shows the dead tracts, notice how they are ofequal length and of approximate distances from each otherand how they extend through the entire thickness of dentineand they are dead coz odontoblastic processes were killedby a stimulus

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This is a slide showing different layers of dental pulp

1 Supraodontoblastic layer2 Odontoblastic layer3 Subodontoblastic layera. Cell free zone of Weilb. Cell rich zone4 Core of dental pulp

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This is a clearer slide showing dentine and dental pulp

1 Odontoblastic layer2 Cell free zone of Weil3 Cell rich zone4 Predentine

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This slide represents unerupting tooth

1 Reduced enamel epithelium (exists on the top surface ofenamel as long as the tooth isn't erupting yet but once iterupts into the mouth it disappears and appears to cover the

cervical part of enamel only but not the surface)2 Enamel (mature, appears as space)3 Dentine4 Dental pulp

This slide represents the apical part of the root

1 Root diaphragm (the only region at which the epithelialroot sheath cells don't disintegrate)2 Proliferation zone of Dental papilla

3 Proliferation zone of Dental follicle

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1 Epithelial rests of malassayz (remnants of ERS)2 Root dentine3 Odontoblasts

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Arrow heads = Epithelial rests of malassayz (aggregation ofcells in the PDL)

** How many roots is this tooth going to have??

2 roots

1111stststst rootrootrootroot 2222ndndndnd rootrootrootroot

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1 Dentine2 Predentine3 Cementum4 Cementoblasts5 Epithelial rests of malassayz

6 PDL7 Blood vessels8 is it a blood vessel??Of course not it is an osteon (building unit of bone)9 Alveolar bone

Arrow head = Cellular cementum

2 Arrow heads = cementocytes


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Arrow heads = Incremental lines of cementum


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The encircled structure shows odontoclasts than are eatingthe root of the deciduous tooth

Thank you all and good luck in your final exams

Done by:

Tahany M. Abu Al - Teen

the most important slides of oral histo lab for the 1st 7 labs

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