Dentin & Pulp (Lecture 2) Flashcards by J L

____ and ____ – Dental Epithelium is Inductive

____ and ____ – Dental Papilla Mesenchyme is Inductive

Lamina
Bud

Cap
Early Bell Stage

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Odontogenesis is first initiated by factors residing in the ____, which then influences the ____.
• With time this potential is switched over to the ____ such that the ____ becomes the driving force in tooth development.
• First signs of tooth development occur at ____ in utero.

1st arch epithelium
ectomesenchyme

ectomesenchyme
ectomesenchyme

5-6 weeks

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Crown Formation
• Six stages of development.
– Dental lamina stage – initial ____.
– ____ stage - proliferation.
– ____ stage – proliferation, differentiation, morphogenesis.
– ____ stage - proliferation, differentiation, morphogenesis.
– ____ stage – induction & proliferation.
– ____ stage – maturation.

induction
bud
cap
bell
apposition
maturation

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Dental Lamina
• ____ cells induce oral epithelium → a horseshoe-shaped ridge forms along each jaw.
• Epithelial ridge → ____.
• Ten locations on each ridge → ectomesenchyme induction of tooth buds – early ____.
• Each primary tooth forms a ____. Permanent molars form their ____.

ectomesenchyme
dental lamina
enamel organs
successional dental lamina
dental lamina

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Crown Formation
• Crown formation begins with development of the ____, then progress through three stages

• 2. Bud stage.
– Initiation of proliferation of ____ epithelial cells into tooth buds.
– ____ buds on each jaw.
– Ectomesenchyme begins to condense around epithelial bud.
– Congenital absence of teeth usually a result of an ____ in this phase

enamel organ
dental lamina
ten
interruption

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Crown Formation •

Cap stage.
– ____: unequal proliferation of bud cells → cap.
– Cytodifferentiation: the epithelial cells begin to differentiate into ____ distinct layers of the enamel organ.
– Shape of tooth becomes ____ as enamel organ begins formation
– Ectomesenchyme cells continue to condense around developing cap: these will become the ____ and ____.

morphodifferentiation
four
evident
dental papilla (DP)
dental sac (DS)

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Crown Formation •

Cap stage (cont).
– ____ = enamel organ + dental papilla + dental sac (dental follicle).
– Successional dental lamina forms on ____ side of dental lamina.
• Will give rise to the ____ of the permanent (successional) teeth.

tooth germ
lingual
enamel organs

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The Tooth Germ

Enamel organ -- an
\_\_\_\_
derivative
Dental papilla -- an
\_\_\_\_ 
derivative
Dental sac – an \_\_\_\_  derivative

epithelial (ectoderm)
ectomesenchyme
ectomesenchyme

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ENAMEL ORGAN
• Derived from \_\_\_\_ via the dental lamina
• The source of \_\_\_\_
• Determines the \_\_\_\_ of the crown
• Induces the formation of \_\_\_\_
• Establishes the \_\_\_\_
• Forms the \_\_\_\_ of the tooth

oral epithelium
ameloblasts
shape
dentin
dentogingival junction
enamel

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DENTAL PAPILLA
• Derived from \_\_\_\_
• The source of \_\_\_\_
• Forms the \_\_\_\_ and \_\_\_\_ of the tooth
• Determines which \_\_\_\_ will be made

ectomesenchyme
odontoblasts
dentin
pulp
type of tooth

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DENTAL SAC
• Derived from ____
• The source of ____
• Forms the ____, periodontal ligament, and alveolar bone (collectively these are the supportive structures of the tooth-the ____. Also referred to as the ____.)

ectomesenchyme
cementoblasts
cementum
periodontium
attachment apparatus

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Crown Formation
• 4. Bell stage.
– The enamel organ is \_\_\_\_
– The location of the \_\_\_\_ will be determined at this stage
– Continued differentiation of enamel organ produces four distinct layers with different functions:
• \_\_\_\_. 
• \_\_\_\_.
• \_\_\_\_.
• \_\_\_\_.

fully formed
DEJ
outer enamel epithelium
stellate reticulum
stratum intermedium
inner enamel epithelium

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Enamel Organ
• Outer enamel epithelium (OEE).
– ____ for enamel organ. – Associated with ____.

• Stellate reticulum.
– Cells secrete ____ (GAGs).
– GAGs draw water into enamel organ ____ its volume.

protective outer barrier
capillary plexus

glycosaminoglycans
increasing

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Enamel Organ
• Stratum intermedium.
– A layer of ____ cells adjacent to IEE cells.
– Essential for enamel formation and mineralization – ____.
– Must be present or ____ will not secrete enamel

• Inner enamel epithelium (IEE).
– Differentiate into ____ – enamel forming cells.
– Initiate ____ formation
– Form the ____ – during cap stage.

spindle-shaped
alkaline phosphatase
ameloblasts

ameloblasts
dentin
enamel knot

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Crown Formation

• Bell stage (cont).
– ____ of the IEE cells establishes the major cusps, fissures, and ridges of the final crown pattern
– ____ joining tooth germ to oral epithelium begins to ____

folding
dental (lateral) lamina
breakdown

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Crown Formation

• Bell stage (cont).
– ____ – junction of OEE and IEE.
– Dental papilla cells continue to proliferate into:
• ____ (future odontoblasts). • ____.
– Dental sac cells continue to proliferate, but will develop into ____ at a later stage.

cervical loop
outer dental papilla
inner dental papilla cells
periodontal tissues

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Crown Formation •

Apposition stage.
– Terminal ____ of ameloblasts and odontoblasts
– Initiation of ____ and ____(odontogenesis)
– Stage during which organic matrix of enamel and dentin are laid down followed by initial ____.
– Series of reciprocal inductions occur between ____ and ____ cells.

differentiation
amelogenesis
dentinogenesis
calcification
enamel organ
dental papilla outer

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Apposition Stage

IEE cells induced to differentiate into ____ (A)

Polarized preameloblasts induce ____ cells to differentiate into ____, which continue differentiating into ____ (B)

preameloblasts

outer DP
preodontoblasts
odontoblasts

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Apposition Stage

Odontoblasts begin to secrete organic matrix of dentin, called ____ (C)

Predentin induces differentiation of ____ into ____ (C)
** some say contact of ____ with ____ induces differentiation

predentin
preameloblasts
ameloblasts
preameloblast
odontoblastic process

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Apposition Stage

Ameloblasts begin secreting enamel matrix which ____ calcifies to ____

immediately

~25-30%

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Apposition stage (cont).

• Events(cont):
– ____ forms after disintegration of basement membrane.
– Odontoblasts retreat from the DEJ leaving ____ within predentin.
– Space containing process is a ____.
– ____ retreat from the DEJ as enamel matrix is deposited (____ mineralized).
– Prismless enamel is formed by ____ secretory ameloblasts.
– ____ are formed by ____ of ____ secretory ameloblasts.

dentioenamel junction (DEJ)
odontoblastic processes
dentinal tubule
ameloblasts
30%
early
enamel prisms
Tomes' processes
late

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Maturation stage

Enamel
– True secreting ameloblast (enamel rods/prisms instead of amorphous): ____ present (E)
– After deposition and initial mineralization of enamel, secretory ameloblasts ____ Tomes’ processes. (F)
– Maturating ameloblasts differentiate and remove ~____ enamel proteins and water, and pump additional ____ into the matrix. (ruffled ameloblasts, G)

tome’s process
lose
90%
Ca++

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Maturation stage

Enamel
- Final differentiation of ameloblasts into ____. (H)
– Basal lamina type material (enamel cuticle) secreted and ameloblasts attach to enamel surface via ____.
– This will become the ____ after eruption.
– ____ forms after enamel is fully matured (remnant of ____).

protective ameloblasts
hemidesmosomes
epithelial attachment
reduced enamel epithelium (REE)

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Timing of developmental stages

Pr. epith band:
Bud stage:
Cap:
Bell:
Crown:

The terms (bud, cap, bell, crown) refer to the ____ in the dental organ.

5 weeks, initiation
6-8, in-growth
8-12, morphogenesis
12-16, differentiation
18, mineral forms

morphological changes

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Introduction to odontogenesis * How a tooth develops from a few cells in the primitive oral cavity to an ____ with crown and ____. * Later material on dentin, pulp, enamel and periodontal ligament * A theme is continual interactions between ____ and ____ cells.

erupted tooth root epithelial mesenchymal

Properties of Mature Dentin ``` • Physical. – Light ____ color. – Resilient – absorbs ____ forces. – Hardness: more mineralized than ____ or ____ but less than ____. • Chemical. – Inorganic – ____ - HA. – Organic – 20% - Primarily ____. – Water – ____. ```

``` yellow masticatory cementum bone enamel 70% type I collagen 10% ```

Properties of Mature Dentin * A vital tissue. * ____ growth throughout life of tooth. * Able to repair itself at ____ side. * The apatite crystal is oriented ____ to the collagen fibers in the dentin matrix (not ____ to ____)

``` continued pulpal parallel parallel dentinal tubules ```

Properties of Mature Dentin * No ____ are present in normal dentin, only a portion of the cell called the ____ (____) is located within ____ in the dentin. * The cells of the dentin, ____, are located within the ____ of the tooth.

``` cells odontoblastic process Tome's fiber tubules odontoblasts pulp ```

``` Dentin • Characteristics. – Resilient support for enamel. – Inorganic – 70%*. • ____ crystals. – Organic – ____*. *by ____ • Primarily ____, also amorphous ground substance. – Water – ____*. – Forms throughout ____ of tooth. ```

``` hydroxyapatite 20% weight type I collagen 10% life ```

Dentinal Structure 1) ____: – Tubular spaces w/in dentin containing odontoblast processes and interstitial fluid. – Approximately 1 in 10 contain ____. – Extend from the ____ to the dentin-predentin junction – ____ in crown; ____ in root. Thus, primary curvatures of the dentinal tubules is ____ in root dentin than in crown dentin

``` dentinal tubules nerve fibers dentinoenamel junction s-shaped straight LESS ```

Dentinal Structure 2) ____. – Extend from cell body out into dentinal tubule. – In mature dentin not all the way to DEJ or DCJ. – Have numerous side branches. – Adjacent cell processes contact via their side branches within ____. – Process tapers from cell body towards ____.

odontoblast processes canaliculi DEJ or DCJ

``` Dentin Structural Features • ____. – Incremental growth lines. – Distance between successive lines of von Ebner represents the ____ of dentin deposited over a period of ____. • 4μm in crown, 6μm in root. ```

Incremental Lines of Von Ebner amount 24 hours

Dentin Structural Features • ____. – Wider, thicker incremental lines – Represent ____ occurring during mineralization. • ____. – Accentuated contour line of Owen. – Represent sudden ____ that occur at birth.

Contour lines of Owen metabolic disturbance neonatal line physiologic changes

Classification of Dentin • Primary dentin. – Dentin formed prior to and during tooth eruption (prior to ____). – ____ and ____: major portion of crown and root dentin.

root completion mantle circumpulpal

Classification of Dentin • Secondary dentin. – Dentin formed after tooth is in ____ (____ root completion). – Continues throughout ____ of tooth. – Forms along entire ____ border. – Rate of formation ____ than primary dentin. – Junction between 1° & 2° dentin is characterized by a sharp change in ____ of dentinal tubule.

``` occlusion affter life pulp-dentin slower direction ```

Classification of Dentin • Tertiary dentin. – Forms very rapidly in response to ____ such as attrition, abrasion, erosion, moderately advancing dental caries, trauma – Forms on the ____ of the dentin in response to ____ – Only deposited at sites where ____ are exposed (localized). – Seals off tubules from ____. – Sparse and irregular dentinal tubules. – May contain cells - ____

``` irritants pulp surface caries dentinal tubules pulp osteodentin ```

Types of Tertiary dentin – ____ dentin. – ____ dentin.

reactive | reparative

Reactive dentin: – Formed by ____ odontoblasts. – Newly formed tubules continuous with those of ____.

preexisting or original | secondary dentin

Reparative dentin: – Formed by ____ differentiated odontoblasts. – Preexisting dentinal tubules ____.

newly | discontinuous

Classification of Dentin • Mantle dentin. – Outer, ____ layer of crown and root primary dentin - nearest to ____. – Size and orientation of collagen fibers different from those in ____ dentin. – Contain thick ____ (____ collagen), oriented ____ to DEJ.

``` first-formed DEJ/DCJ circumpulpal von Korff's fibers Type III perpendicular ```

``` Classification of Dentin • Circumpulpal dentin. – ____ of primary dentin, any secondary dentin and tertiary dentin. – During the lifespan of a multirooted tooth, dentin forms most rapidly on the ____ and ____ of the pulp ____ – Contains mainly ____ collagen. – Collagen fibers. • ____ in diameter. • More ____ oriented. ```

``` remainder floor roof chamber Type I smaller randomly ```

Classification of Dentin • Predentin. – A layer of newly secreted organic matrix. – Always present between ____ and mineralized ____. – ____ - similar to osteoid in bone.

odontoblasts dentin unmineralized

``` Classification of Dentin • ____ dentin (or ____ dentin) . – Highly calcified dentin. – Lines the wall of the ____. – 40% more calcified than ____ dentin, most mineralized of all dentin. – Few collagen fibers; dentin ____. – Not in ____ or ____. ```

``` peritubular intratubular dentinal tubule intertubular sialoprotein mantle interglobular dentin ```

Classification of Dentin • ____ dentin. – All dentin located between ____ - majority of dentin. – ____ product of odontoblasts. – ____ calcified than intratubular dentin. – Contain ____ collagen fibrils. • Dense, interwoven. • ____ within fibrils.

``` intertubular dentinal tubules primary less type I hydroxyapatite ```

Dentin Histology pathological dentin ``` • ____. – Area of dentin where dentinal tubules completely ____ with minerals. – Appears ____ under microscope. – ____ – apical 1⁄3 of root and crown midway between DEJ and pulp. – ____ w/age. – Forensic dentistry – ____. ```

``` sclerotic dentin occluded transparent most common increases aging factor ```

Classification of Dentin • Dead tract dentin. – Tract of dentin containing ____ dentinal tubules (often has ____associated with it). – Forms when ____ either killed or injured and processes retracted, leaves empty dentinal tubules. – Appears ____ w/transmitted light in ground sections as only air is present (thus “dead tract”). – Usually in ____ dentin. – Usually sealed off by ____.

``` empty sclerotic dentin odontoblasts black coronal tertiary dentin ```

``` Age & Functional Changes • Secondary dentin. – ____ volume of pulp. – May lead to true ____. • Tertiary dentin. – ____ volume of pulp. • Sclerotic dentin. • Dead tract dentin. ```

decreases pulp stones decrease

``` Pulp • Only ____ of the tooth. • A specialized ____ connective tissue. – Derived from ____ – After the tooth is formed, the ____ remains as the dental pulp • Functions. – Formation. – Nutrition. – Defense. – Sensation. – Reparative. • Forms throughout ____ of tooth. ```

soft tissue loose dental papilla life

``` Pulp Pulpal Anatomy – Coronal pulp • Located in the pulp ____ and pulp ____ – Radicular pulp • Located in pulp ____ ```

chamber horns canals

Pulpal Anatomy • Apical foramen & accessory canals – ____ • Where nerves, blood vessels and lymphatic vessels enter and leave the tooth. • Communicates w/ the ____. • Local resorption/deposition of cementum & local resorption of dentin may change the ____ of apical foramen. – Accessory canals • Connections between pulp ____ and ____. • Formed by a break in the ____ – HERS detach too ____ during development.

``` apical foramen PDL position/shape canals PDL Hertwig epithelial root sheath early ```

``` Zones of the Pulp • Four zones. – Odontoblastic layer. • Outermost layer against ____. • ____ located between cells. – Cell-free zone (of Weil). • Not “cell-free” – ____ cells. • Capillary and nerve plexus (____). ```

predentin dentinal nerve fibers fewer plexus of raschkow

Zones of the Pulp • Four zones (cont). – Cell-rich zone. • Increased ____ – mainly ____ (most abundant cell type in the pulp). – Pulp core or central zone. • ____ region of pulp. • Numerous cell types, nerves and blood vessels and lymphatic vessels.

cell density fibroblasts central-most

``` Cells of the Pulp • Cell types. – Fibroblasts – ____ numerous. – Odontoblasts – ____ numerous. – Undifferentiated mesenchymal cells. – Macrophages. – T-lymphocytes. – Leukocytes. • ECM – amorphous ground substance (AGS), collagen & reticular fibers. ```

most | next

``` Cells of the Pulp • Odontoblasts. – Origin – ____. – Cuboidal to columnar cells. – Located at the ____ of dental pulp. – Extend a long process into ____. – Responsible for the formation and maintenance of ____ and ____. – May play a critical role in ____. – ____ damaged dentin. ```

``` neural crest-derived ectomesenchyme periphery dentinal tubule predentin dentin pain perception repair ```

Cells of the Pulp • Fibroblasts. – Synthesize collagen fibers, glycosaminoglycans, proteoglycan, and glycoproteins of the pulp matrix. – Phagocytize and degrade ____. – Responsible for “turn over” of the ____ – ____ in number with age.

collagen fibers pulp extracellular matrix decrease

``` Cells of the Pulp • Undifferentiated mesenchymal cells. – Pluripotent cells that may differentiate into ____ or other cells as needed for repair of dentin or the pulp itself. • Macrophages. – Originate from blood ____. – Located throughout the ____. – Involved with elimination of ____. ```

odontoblasts monocytes pulp dead cells

Cells of the Pulp • Lymphocytes. – T- and B- lymphocytes, but B- are ____. • Dendritic cells. – ____ antigen-presenting cells. – Located ____ odontoblasts layer in erupted teeth. – Similar to Langerhans cells in integument. – Capture and present foreign antigen to ____. – ____ in number in carious teeth. • Infiltrate ____ layer. • Send their processes into ____.

``` scare class II beneath T-lymphocytes increase odontoblast dentinal tubules ```

Pulp Matrix • Contains collagenous fibers, Types ____ and ____. • Lack of ____ except in the walls of blood vessels. • Ground substance consists of proteoglycans and glycoproteins. – Proteoglycans bind large amount of water. This water, plus some free water, amounts to ____ of the pulp matrix by weight. – Glycoproteins include fibronectin, chondronectin, osteonectin & laminin.

I III elastic fibers 90%

Innervation of the pulp • Nerve bundles entering the dental pulp consist primarily of: – Sensory _____ nerves of the ____ (fifth cranial nerve), and – Postganglionic sympathetic branches from the ____ - innervate Pulpal blood vessels. – Each bundle consists of both ____ and ____ axons. • Myelinated fibers lose their myelin sheath as they approach the ____.

``` afferent trigeminal nerve superior cervical ganglion myelinated unmyelinated coronal pulp ```

Nerve Fibers • Pain fibers – ____: associated with sharp localized pain – ____: associated with dull, diffuse pain. • Others – ____: have a larger diameter, compared to A-delta fibers • Autonomic – Sympathetic only: ____

A-delta fibers C-fibers A-beta fibers C fibers

Nerve Fibers • A-delta fibers – ____ fibers in pulp-dentin border of the coronal portion. – ____ of fibers entering the pulp. – ____ conducting. – Diameter = 1 to 6 μm [about 1% have diameters of 6 to 12 μm and are designated Aβ fibers]. – Associated with ____ pain when ____ is first exposed.

``` myelinated majority fast sharp localized dentin ```

Nerve Fibers • C fibers – ____ fibers in the ____ of the pulp and extend into the ____ zone. – ____ conducting. – Diameter = 0.4 to 1.2 um. – Associated with ____ pain. – ____ nerves also this type.

``` nonmyelinated core cell-free slow dull, diffuse sympathetic ```

Nerve fibers • Postganglionic sympathetic nerves: – ____ fibers. – Regulate intravascular and interstitial ____ within the pulpal tissues. – Increased sympathetic stimulation ____ the pulpal blood flow, but does not change the ____ of the blood vessels in the dental pulp.

unmyelinated C pressures decreases diameter

Sensory Perception • Sensory—extremes in temperature, pressure, or trauma to the dentin or pulp are perceived as pain – Pain originates in the ____ due to ____ about the odontoblastic cells – *NOTE: in peripheral organs, the free nerve endings are ____ stimulated by pain (not touch, pressure, temp...)

pulp free nerve endings receptors

Dentin Sensitivity • General. – Extreme sensitivity of pulp-dentin complex is unusual and difficult to explain. – Major sensation perceived – ____. – Mechanical, thermal and tactile stimuli also picked up by Pulpal ____ nerves. – Products like bradykinin and histamine, which produce pain in other tissues, ____ produce pain in dentin.

pain afferent do not

Dentin Sensitivity • Three theories. – ____. • 1 in 10 tubules contains a free nerve ending. – ____. • Nerves shown to synapse on odontoblast cell body. – ____. • ____ movement through tubule stimulates pulpal nerves. • Most ____ theory.

``` nerves in dentin odontoblast as receptor hydrodynamic fluid plausible ```

Blood supply to the pulp • Arterioles and venules enter pulp at ____ from superior and inferior ____ arteries. • Branching occurs as vessels approach ____ pulp and pulp horns. • Forms an extensive capillary network (bed) deep to ____ layer. • Capillary loops penetrate odontoblastic layer. – Capillaries consist of ____ endothelial cells. – Capillary loops are denser in the ____ compared to the radicular pulp. • Arteriovenous and venous- ____ are present.

``` apical foramen alveolar coronal odontoblastic fenestrated coronal pulp venous shunts ```

``` Pulp Histology • Pulp stones = ____. – True pulp stones. • Ectopic mass of ____ in pulp. • ____ and ____. – False pulp stones. • ____ mass in pulp. • Concentric rings of ____. – ____: free, attached or embedded. ```

``` denticles dentin odontoblasts dentinal tubules calcified lamellae location ```

``` Age Changes in Pulp • ____ - increased collagen fiber content. • Blood and nerve supply ____. • Decreased volume due to: – ____. – ____. – ____. ```

``` fibrosis decrease secondary dentin tertiary dentin pulp stones ```