physiology Flashcards
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
Why is Ludwigs angina so dangerous
Life threatening cellulitis which can advance to pharyngeal and cervical spaces–airway obstruction
Difference between sublingual, submental and submandibular space infections?
All break through lingual plate
Above mylohyoid: sublingual
Ant below mylohyoid: submental
Post below mylohyoid: submandibular
For a buccal vestibule infection, the MAND apices must lie above the?
buccinator or mentalis muscle attachment
Laskin-which way do apices of teeth point?
Usually facial, except max laterals (50%) and mand molars (1st ?, 2nd 50%, 3rd usually)
For a buccal vestibule infection, the MAX apices must lie below the?
buccinator muscle attachment
For a buccal space infection where must apices lie?
max-above the buccinator, mans-below the buccinator
Difference between buccal vestibule infection and buccal space infection?
buccinator muscle attachment (for a space infection, max teeth must be above it, and mand teeth below it)
What is infection around the eye called?
Periorbital (spread from canine or buccal space infections)
Why are infections of the mid face dangerous?
Cavernous sinus thrombosis
Do cysts heal following NSRCT? Says whom?
Pocket cysts, yes. True cysts less likely. Nair
What is the difference between a true cyst and pocket cyst. Who defined them?
True cyst: completely enclosed by epithelial lining. Bay/pocket cyst: lined with epithelium, but communicates with root canal
Simon
Eliasson 1984- condensing osteitis?
73% of condensing osteitis healed completely with NSRCT, it did not progress in any cases.
Who showed that 73% of condensing osteitis healed completely with NSRCT, it did not progress in any cases?
Eliasson 1984
Bone is resorbed by osteoclasts. What are the two signaling molecules that act on the osteoclasts and osteoblasts to regulate the amount of bone to be resorbed?
RANKL: stimulates osteoclast formation
OPG: inihibits osteoclas formation
What is the dental papilla? What type of cells is it made of?
The tissue inside the “bell” that becomes the pulp. Ectomesenchymal cells from the dental papilla mingled with local mesenchymal cells.
Mesenchymal cells become…
the dental papilla
What is the dental lamina made of?
Epithelial cells (it invaginates from the oral epithelium). Bud–> Cap –> Bell
The inner layer of the enamel organ (the internal dental epithelium) differentiates into what?
ameloblasts
what controls how much enamel and dentin get laid down?
The interactions between the ectomesenchymal cells and the epithelial cells
first layer of dentin to be laid down?
The mantle dentin
What is Hertwig’s epithelial root sheath made of?
The meeting of two fused epithelial layers (inner dental epithelia and outer dental epithelia)
How do multiple roots form?
Hertwig’s epithelial root sheath proliferates not just in a vertical direction, but a horizontal direction.
What does the hyaline layer of Hopewell-Smith do?
binds newly formed cementum to dentin
What causes radicular cysts?
The remnants of Hertwig’s Epithelial Root Sheath stay in the PDL (called the epithelial Rests of Malassez) sometimes proliferate with inflammation and give rise to radicular cysts
How does cementum form
Once the root sheath breaks down, the mesenchymal cells of the follicle differentiate into cementoblasts that lay down cementum on top of the hyaline layer
What are Sharpey’s fibers?
Bundles of collagen laid down by mesenchymal cells of the follicle that have differentiated into fibroblasts.
What do Sharpey’s fibers do?
Become embedded in the forming cementum and become the principal fibers of the PDL.
Five functions of dental pulp?
- Induction of enamel formation
- Lay down dentin
- nutrition
- defense (lay down tertiary dentin)
- sensation
Shape and configuration of odontoblasts?
Single layer of columnar cells.
what two molecules stimulate undifferentiated mesenchymal stem cells to differentiate into odontoblasts
BMP (bone morphogenic protein) TGF beta (Transforming growth factor beta)
What is the most common cell type in the pulp?
Fibroblasts
Largest blood vessels in the pulp:
Arterioles, venules (slightly bigger)
Arterioles in pulp are branches of what three arteries?
Inferior alveolar artery
superior posterior alveolar artery
infraorbital artery
Venules in pulp drain what two ways?
Into maxillary vein thru pterygoid plexus
anteriorly into facial vein
Where do lymphatics of pulp drain?
Into submental, submandibular, or cervical before emptying into subclavian and internal jugular veins
What is harder, cementum or bone?
cementum
Who said that necrosis extends gradually from upper portion of pulp to apical portions?
Yamasaki
Current data suggests that what is responsible for increased blood flow in pulpal inflammation?
CGRP
What do kinins do?
Cause many signs and symptoms of acute inflammation
What kind of pulps have Mast cells?
Inflamed pulps (they are no present in healthy pulps)
Difference between a cyst and granuloma?
A cyst is lined by stratified squamous epithelium, surrounded by connective tissue
What is condensing osteitis often confused with?
Enostatsis (sclerotic bone in the posterior mandible that is a non-pathologic entity)
Dendritic cells make up what percentage of the pulp?
8%
fastest conducting nerve fibers in the pulp?
A beta
what is CRP? What is it produced in response to?
C-reactive protein, produced in response to IL-6, and prototype component of acute-phase proteins.
