Oral Histology, Embryology & GeneticsDent 5315/DH2215 February 19, 2008

Embryology in The News

Dentinogenesis - The Formation of Dentin

A. Dentinogenesis

B. Root Formation

C. Dentin-Pulp Complex

D. Dentin Classification

E. Clinical Correlations

“Origins”

THE DENTIN-PULP COMPLEX

THE DENTIN-PULP COMPLEX

Dentin and pulp are related: a. embryologically b. histologically c. functionally

dental papilla/pulp

THE DENTIN-PULP COMPLEX

THE DENTIN-PULP COMPLEX

Mature dentin-pulp complex

Note vascularity of pulp

“Subodontoblastic plexus of Raschkow” occupies cell-free zone of Weil (crown only)

THE DENTIN-PULP COMPLEX

Note: a. dentin tubules &

odontoblastic processes

b. irregular mineralization fronts (arrows)

DENTIN CLASSIFICATION

Types of dentin: globular/interglobular

DENTIN CLASSIFICATION

Types of dentin:

Interglobular dentin is especially noticeable in vitamin D deficiency, high levels of fluoride, etc..

DENTIN CLASSIFICATION

Junction of primary & secondary dentin.

DENTIN CLASSIFICATION

Types of dentin:

DENTIN CLASSIFICATION

Types of dentin: reparative/tertiary dentin

What can initiate this type of dentin?

Exposed open tubules, caries, restorations, chemicals such as etching, etc.

ENAMEL vs DENTIN

Types of dentin: reparative/tertiary dentin

Note “S-shaped” tubules in coronal region

&

“dead tracts”

DENTIN CLASSIFICATION

Typical radiographic appearance of internal root (dentin) resorption.

Why does this tooth appear pink?

DENTIN CLASSIFICATION

Internal resorption with root perforation (arrow)

dentin tubules

“giant cells”

DENTIN CLASSIFICATION

Area of normal tubular dentin (arrow) & area osteodentin.

Note multinucleated giant cells resorbing both calcified reparative tissue & primary dentin.

DENTIN CLASSIFICATION

Types of dentin: inter & intra globular dentin

Inter = between

Intra = within

DENTIN CLASSIFICATION

Types of dentin: sclerotic/transparent dentin

www.kck.usm.my/ppsg/histology/ Histopathology_of_dental_Dental_caries_1.ppt -

CLINICAL CORRELATIONS

Cavity preparation in dentin1. How does a knowledge of dentin affect cavity preparation? a. amputation of

odontoblastic processes

b. communication to pulp

c. placement of bases, pulp injury (heat, acid etch, etc.)

d. progression of caries

bacteria

CLINICAL CORRELATIONS

Note areas of demineralization

“Rampant” Caries

Clinical Correlations

2. What makes dentinstructure susceptible to caries?

A. Dentin has a tubular structure.

B. Caries can spread along DEJ.

C. Crystals dissolve at low pH produced by cariogenic bacteria.

CLINICAL CORRELATIONS

Horizontal clefting right angle to dentinal tubules.

Bacterial beading, coalescence, clefting typifies progression of dentinal caries.

CLINICAL CORRELATIONS

3. What is dentin hypersensitivity? Why is dentin sensitive?

Pain due to communication between outside environment & pulp.

3 Theories of dentin hypersensitivity. (Fig. 8-61)

CLINICAL CORRELATIONS

Dentin hypersensitivity

Loose/defective restoration Dessication forces

CLINICAL CORRELATIONS

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