Dentin & Pulp (Lecture 2) Flashcards
____ and ____ – Dental Epithelium is Inductive
____ and ____ – Dental Papilla Mesenchyme is Inductive
Lamina
Bud
Cap
Early Bell Stage
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
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
- 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
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
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)
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
The Tooth Germ
Enamel organ -- an \_\_\_\_ derivative Dental papilla -- an \_\_\_\_ derivative Dental sac – an \_\_\_\_ derivative
epithelial (ectoderm)
ectomesenchyme
ectomesenchyme
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
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
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
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
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
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
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
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
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
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
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
Apposition Stage
Ameloblasts begin secreting enamel matrix which ____ calcifies to ____
immediately
~25-30%
- 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
- 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++
- 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)
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
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
