4075263
Structure of pulp-dentin complex
- Background info
- 70% dentine is inorganic
Hap | 20% is organic (90%
collagen, 10% GS) | 10%
water
- 3 Types (1°, 2°, 3°)
- Enamel > Dentine >
Bone hardness
- Pulp > Dentine > Enamel
opacity on radiograph
- 70% dentine is inorganic
Hap | 20% is organic (90%
collagen, 10% GS) | 10%
water
- Dentinal tubules
- Produced as the odontoblasts
secrete dentine and migrate
pulpally - leaving behind
cytoplasmic extension
embedded in dentine
- S- shaped course in coronal dentine
(crowding) | Straight course in
pulpal dentine (less SA - less
crowding)
- Tapered (thinnest at ADJ -
largest at pulp)
- Older = sclerotic (type of
peritub. dentine) = dentinal
tubules occluded - glassy
appearance
- Peritubular -
hypermineralised sections
of dentine immediately
surrounding tubules
- Produced as the odontoblasts
secrete dentine and migrate
pulpally - leaving behind
cytoplasmic extension
embedded in dentine
- 3 main types of dentine
- 1° - Outlines the pulp
chamber, forms the bulk of
the tooth - two "layers" - thin
mantle layer, bulkier cirpl.
dentine
- 2° - Secreted after root formation at
slower rate. Uneven distribution - lots
near roof + floor of MOLAR pulp
chambers.
- 3°
- Reactionary - pre-existing OD secrete 3°
dentine
- Reparative - newly differentiated
OD-like cells secrete 3° dentine
- Secreted in response to noxious stimuli.
Intensity of stimulus is proportional to strength
of 3° dentine laid down. Only OD DIRECTLY
affected by noxious stimuli secrete 3° dentine.
- Reactionary - pre-existing OD secrete 3°
dentine
- 1° - Outlines the pulp
chamber, forms the bulk of
the tooth - two "layers" - thin
mantle layer, bulkier cirpl.
dentine
- Features + categories of dentine
- INTERTUBULAR DENTINE
- Forms the bulk of
the dentine
- Network of type 1
collagen embedded in
ground substance (GP =
PG's, Phospho's)
- Forms the bulk of
the dentine
- Globular/Interglobular dentine
- Hypomineralised areas of
dentine - failures of "globules"
of mineralisation to fuse into
one mass = forms
INTERGLOBULAR dentine
- No peritubular
dentine found
here
- Vit D def. / Fluorosis
causative factors
- Hypomineralised areas of
dentine - failures of "globules"
of mineralisation to fuse into
one mass = forms
INTERGLOBULAR dentine
- Incremental growth lines - showing phases
of quiescent/secretory activity. 5 days
patterns = incremental lines of Von Ebner
(20 microns apart). Incremental lines can be
visualised as tetracycline treatment courses
end up colouring these lines as they
develop
- Granular layer of Tomes
- Only seen in ground sections
- Black "dots" at CDJ
- Small air spaces
due to root
dentinal tubules
slow rate of
secretion
- Only seen in ground sections
- INTERTUBULAR DENTINE
- Age changes in dentine-pulp
- Sclerotic dentine (occludes
dentinal tubules)
- Secondary dentine
occludes pulp chamber
- Sclerotic dentine (occludes
dentinal tubules)
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