The document discusses dentin, the bony tissue that makes up the bulk of the tooth below the enamel. It describes dentin's physical properties, including its composition of hydroxyapatite and collagen, and that it is harder than bone but softer than enamel. It also discusses the histology of dentin, including dentinal tubules that contain vital contents and the different types of dentin like primary, secondary and tertiary dentin.
1. “a tooth is composed of
two substances viz
enamel and bone…”
DR. SHUBHANGI MISHRA
2. ‘a tooth is composed of two substances viz
enamel and bone’ and
‘the other substance of which a tooth is
composed is bony; but much harder than
the most compact part of bones in
general’
DR. SHUBHANGI MISHRA
14. Physical
Properties
• YELLOW (effect of age?)
• Located both on crown and root
• Second hardest tissue of the body
• 66%-70% mineralized (calcium
hydroxyapatite)
• 20%-25% organic (collagen and
ground substance)
• 10% bound water
• Highly elastic and resilient
• LIVING tissue (why is enamel not
living?)
• Harder than bone, softer than
enamel!
DR. SHUBHANGI MISHRA
17. Histology of DENTIN
• Dentinal tubules
• Peritubular dentin
• Intertubular dentin
DR. SHUBHANGI MISHRA
18. Dentinal Tubules
• Tubules with VITAL contents!
• Diameter more towards pulp than enamel
• Density more towards pulp than enamel (4 times)
DR. SHUBHANGI MISHRA
24. Peritubular Dentin
• Found throughout dentin except nearer to pulp (present in minimal amount)
• Thicker in outer dentin than towards pulp
• 9% more mineralized than intertubular dentin
• On the inner side, thin organic membrane called the lamina limitans
DR. SHUBHANGI MISHRA
25. Intertubular dentin
• Forms the main body of dentin
• Less mineralized than peritubular dentin
• About one half is organic (Collagen fibrils)
• Hydroxyapatite crystals arranged parallel to the fibres
DR. SHUBHANGI MISHRA
32. TYPES OF
DENTIN
• Mantle dentin
• Circumpulpal dentin
Primary dentin
Secondary dentin
Tertiary dentin
DR. SHUBHANGI MISHRA
33. Primary dentin
- Mantle Dentin (20 µ)
• First-formed dentin
• Just below DEJ
• Soft (to provide cushioning effect)
• Organic part has larger collagen fibrils (von Korff’s fibres) as
compared to rest of the primary dentin
• Less mineralised than circumpulpal dentin
• Fewer defects than circumpulpal dentin
• Matrix vesicles are involved in the mineralisation of mantle dentin
DR. SHUBHANGI MISHRA
34. Primary dentin
- Circumpulpal dentin
• Remaining primary dentin
• Bulk of the tooth
• All of the dentin that forms BEFORE completion of
root
• Smaller and more closely packed collagen fibrils
• Slightly more mineral than mantle dentin
DR. SHUBHANGI MISHRA
36. Secondary dentin
• Narrow band around the pulp
• Dentin formed AFTER root completion
• Fewer tubules than primary dentin
• A bend in the tubules at the primary and secondary dentin
interface
• Formation: Slow, uneven, and more on the floor and roof of
pulp chamber
• NOT in response to any stimuli
DR. SHUBHANGI MISHRA
39. Incremental Lines
• Of von Ebner
• At 4-8 µ in crown and much lesser in root
• Accentuated ones – Contour lines (of Owen)
• Neonatal line only in ? teeth
DR. SHUBHANGI MISHRA
40. Interglobular dentin
• Sometimes, mineralisation begins in small
globular areas that FAIL to coalesce into a
homogenous mass
• Thus, zones of HYPOminearalisation
between the globules
• Just below mantle dentin
DR. SHUBHANGI MISHRA
42. Think
upon!
The first-formed dentin is
MANTLE DENTIN
When dentin first forms, it is
called PREDENTIN
So, Logically tell the locations of
mantle dentin and predentin!
DR. SHUBHANGI MISHRA
44. Theories of DENTIN SENSITIVITY
1. Direct Neural Transmission Theory
Unacceptance?
- Nerves do not generally extend beyond the
inner dentin
- Topical application of local anaesthetics
does not abolish sensitivity
2. Hydrodynamic Theory
3. Transduction Theory
DR. SHUBHANGI MISHRA