Oral Histology, Embryology & Genetics Dent 5315/DH2215 February 19, 2008

Embryology in The News

Dentinogenesis - The Formation of Dentin Root Formation Dentin-Pulp Complex Dentin Classification Clinical Correlations

THE DENTIN-PULP COMPLEX “Origins”

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 Why does this tooth appear pink? Typical radiographic appearance of internal root (dentin) resorption.

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 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 Cavity preparation in dentin

CLINICAL CORRELATIONS “Rampant” Caries Note areas of demineralization

Clinical Correlations 2. What makes dentin structure susceptible to caries? Dentin has a tubular structure. Caries can spread along DEJ. 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 Product Evaluation