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
