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  • image-2-1421496 CDJ
  • Hyaline layer of hopewell-Smith
  • Zones
  • Functions
  • Diff. b/w AEFC & CIFC
  • Cellular Cementum

Dentowesome 2020 | @dr.mehnaz🖊 tenor-6-9898997

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Dr. Mehnaz Memon🖊

Zone I: Zone of fatty degeneration of odontoblast process
Zone 2: Zone of dentinal sclerosis characterized by deposition of cal- cium salts in dentinal tubules
Zone 3: Zone of decalcification of dentin, a narrow zone, preceding bacterial invasion
Zone 4: Zone of bacterial invasion of decalcified but intact dentin Zone 5: Zone of decomposed dentin

Early dentinal caries

Fatty degeneration of odontob/ast process

>Disposition of fat globules – precedes early sclerotic changes  >Special stains – Sudan red>Significance-

1.Fat contributes to impermeability 

2.Predisposing factor for dental sclerosis

Decalcification of dentinal tubules

>Above dentinal sclerosis – zone of decalcification

>Occurs in advance of bacterial invasion of DT 

>Pioneer bacteria
>The initial decalcification – only the walls of DT 

>Study of tubules- pure form of microorganisms

Zone of microbial invasion

>Proteolytic organisms – predominantly in deeper layers Acidogenic microorganisms – more in early caries
>Supporting the hypothesis that initiation and progression are two distinct processes and must be differentiated

>Decalcification of the walls of DT – confluence

>Thickening of sheath of Neumann – along its course • Increase in the diameter of DT – microorganisms

>Focal coalescence of adjacent tubules and ovoid area of destruction- liquefaction foci
>Acidogenic organisms – initial decalcification

REFERENCE- Shafers textbook of oral pathology 8th edition

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Four zones are clearly distinguishable, starting from the inner advancing front of the lesion. These are the (1) translucent zone, (2) dark zone, (3) body of the lesion and (4) surface layer.

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Zones of enamel caries Translucent zone {TZ)

First recognizable zone of alteration

Advancing front of the lesion

Half the lesions demonstrate TZ, not always present

Seen in longitudinal ground sections in clearing (quinoline – RI – 1.62)

TZ appears structureless

Pore volume – I% (compared to 0.1 % of sound enamel)

Dark zone

Lies adjacent and superficial to the translucent zone Positive zone

Shows positive birefringence (in contrast to sound enamel.

Pore volume of 2-4% (polarized light)Presence of small pores; large molecules of quinoline are unable to penetrateMicropore system – gets filled with air and becomes dark

Medium like water may penetrate

Body of the lesion

Between unaffected, surface and dark zoneArea of greatest demineralization

Pore volume – 5% in periphery and 25% in centre

Quinoline imbibition – body appears transparent

Water imbibition – positive birefringence compared to sound enamel Striae of Retzius – prominent

Surface zone

Quantitative studies – partial demineralization of 1-10% • Pore volume – less than 5% of the spaces

Negative birefringence – water imbibition

Positive birefringence – porous subsurface
All the four zones of enamel caries cannot be seen with same immersion medium.

REFERENCE – Shafers textbook of oral pathology 8th edition

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Notes Credits: ©️Sabrin Shaikh(Final Year Dental Student)

Dentowesome 2020📖📝

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3 major types:

  1. Masticatory Mucosa (Gingiva & hard palate)
  2. Lining or reflecting Mucosa (Lip, Cheek, floor of mouth)
  3. Specialized Mucosa (Dorsum of tongue, taste buds)

🔹Functions:

  1. Defence: Oral Mucosa is impermeable to bacterial toxins. Also secretes antibodies.
  2. Lubrication: Secretion of salivary glands keep the oral cavity moist which helps in speech and mastication.
  3. Sensory: Sensitive to touch, pressure, pain & temperature.
  4. Protection: Protects deeper tissues from mechanical forces resulting from mastication & from abrasive nature of food stuff.

🔹Keratinized Epithelium:

img_6356-6821688 Image source: SpringerLink

➡️ Contains 4 layers starting from the bottom:

▪️Stratum Basale:

  • Single layer of cuboidal cells
  • They synthesize DNA & undergo Mitosis

▪️Stratum Spinosum:

  • Layer is irregularly polyhedral & larger than basal cells

▪️Stratum Granulosum:

  • Layer contains flatter & wider cells
  • Larger than spinous cells

▪️Stratum Corneum:

  • Made up of keratinized squamous which are larger & flatter than granular cells

🔹Keratinized Areas:

  • Masticatory Mucosa
  • Vermilion border of lip

🔹Non-Keratinized Areas:

  • Lining Mucosa
  • Specialized Mucosa

References: Orban’s Oral Histology

Dentowesome 2020 @dr.mehnaz

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References: Shafer’sTextbook Of Oral Pathology

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🌏 African Jaw Lymphoma

🌏 The endemic form is linked to malaria and to the Epstein-Barr virus (EBV), a common virus that also causes glandular fever.

🌏 A tumour peculiar to children of central Africa was reported by Denis Burkitt in 1950. It is a lymphoreticular cell malignancy.

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▪️It is a high grade B-cell neoplasm & has 2 major forms:

🔷 Clinical Features:

1. Age – between 6 & 9 years

2. Sex – M:F – 2:1

3. Site: In African form (Endemic),

  • Maxilla > Mandible
  • Spreads to floor of orbit
  • Molar area
  • More than one quadrant is involved

American form (Non-endemic) – Oral: only 1 quadrant involved. Other: Mainly involves Abdomen.

4. Onset & progress – fast growth with tumor doubling time of