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Percentage of A and C fibers in the dental pulp. Difference between them.

20% A fibers: myelinated
80% C fibers: unmyelinated, do not fire til injury


Two different kinds of A fibers:

A delta (90%)
A beta (10%)


What is dentin, by weight?

70% inorganic, 20% organic, 10%water


Main inorganic component of dentin?

calcium hydroxyapatite


Most common type of collagen in dentin?

type 1 collagen (there's a minor component of type V)


Types of dentin and descriptions:

Primary (before tooth eruption): Regular in structure, dentin tubules are S-shaped, the majority of dentin in a tooth.
Secondary: After eruption, less structured, deposited for rest of tooth's life at slow rate
Tertiary: Deposited as a result of a pathologic process-disorganized in structure


What is mantle dentin? Where is it?

The first layer of primary dentin to be deposited. It's adjacent to the enamel in a crown. Less mineralized (softer). 150 micrometers thick


What dentin constitutes the major part of primary and secondary dentin?

Circumpulpal dentin.


What is predentin?
How thick is it?
Where is it?

15-20 micrometer unmineralized organic matrix layer of dentin situated between the odontoblast layer and the mineralized dentin.


What type of collagen is in predentin?

Types 1 and 2


Is dentin permeability higher or lower near the pulp?Why?

Higher near the pulp, because the tubules occupy a greater percentage of the space (larger tubules).


What is intertubular dentin?

Located between the dentin tubules and constitutes the bulk of dentin. Has lots of collagen.


What is intratubular dentin?

Dentin lining the walls of tubules (also called peritubular). Fewer collagen fibrils, more sulfated proteoglycans and mineral.


Which dentin is more easily dissolved by etch and why?

Peritubular (intratubular)-more mineral and less collagen. So when etch or EDTA is used, the peritubular dentin is removed and the tubules are enlarged.


Is radicular dentin more or less permeable than coronal dentin? Why?

Radicular dentin is much less permeable, due to a decrease in the density of dental tubules (42,000/mm2 in cervical dentin, and 8000/mm2 in radicular dentin)


Who said the functional diameter of tubules is only about 5-10% of the actual anatomic diameter b/c of odontoblast processes, collagen fibers etc.?

Michelich 1978


Michelich 1978

Dentin tubules?

the functional diameter of tubules is only about 5-10% of the actual anatomic diameter b/c of odontoblast processes, collagen fibers etc.


Who said an inflammatory reaction develops in the pulp long before the pulp actually becomes infected with microorganisms?

Trowbridge 1978


What is the outermost stratum of cells in a healthy pulp? What does it lie beneath?

The odontoblast layer. Lies beneath the predentin.


What lies right below the odontoblast layer?

The cell poor zone (cell free layer of Weil). Has lots of capillaries, unmyelinated nerve fibers, and cytoplasmic processes of fibroblasts.


What lies beneath the cell poor zone?

The cell rich zone (lots of fibroblasts, and also immune cells like macrophages and dendritic cells, and also undifferentiated mesenchymal stem cells)


Primary purpose of the pulp?

To grow the tooth--odontoblasts form dentin--most important function!


What is dentin primarily composed of? What is its primary function?

Fibroblasts, odontoblasts


What immune cell is present in the highest number in the pulp?

Dendritic cells (8%) (Antigen Presenting cells)


How are c fibers different from A fibers?

C fibers produce a dull aching pain, and have a higher threshold of excitation.


Pain pathway for a mandibular molar (three nerves and where they end?

Inferior alveolar nerve -- trigeminal nucleus
Secondary nerve--thalamus
Tertiary nerve--cortex


Arterial blood supply for all teeth:

r. atrium, r. ventricle, pulpmonary a., l. atrium, l. ventricle, aorta, common carotid, external carotid, maxillary artery then...
max post: pterygopalatine, PSA
max ant: pterygopalatine, PSA, ASA
mand post: mand a., IA a.
mand ant. mand a., IA a., incisive a.


Venous blood supply for all teeth

maxillary v., pterygoid venous plexus, retromandibular v., internal jugular v., brachiocephalic v., superior vena cava, heart
all mand: IA v., then above
max ant: infraorbital, then above
max post: above


Nerve supply to teeth

Brain stem- trigeminal nerve-
max teeth: V2-PSA-MSA-ASA
mand teeth: V3-IAN-incisive brances


What three spaces are involved in Ludwig's Angina?

Submental, submandibular, sublingual