Dentin & Pulp (Lecture 2) Flashcards Preview

Dental Development and Anatomy > Dentin & Pulp (Lecture 2) > Flashcards

Flashcards in Dentin & Pulp (Lecture 2) Deck (69)
Loading flashcards...
1

____ and ____ – Dental Epithelium is Inductive

____ and ____ – Dental Papilla Mesenchyme is Inductive

Lamina
Bud

Cap
Early Bell Stage

2

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

3

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

4

1. 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

5

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

6

Crown Formation •

3. 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)

7

Crown Formation •

3. 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

8

The Tooth Germ

Enamel organ -- an
____
derivative
Dental papilla -- an
____
derivative
Dental sac – an ____ derivative

epithelial (ectoderm)
ectomesenchyme
ectomesenchyme

9

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

10

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

11

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

12

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

13

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

14

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

15

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

16

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

17

Crown Formation •

5. 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

18

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

19

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

20

Apposition Stage

Ameloblasts begin secreting enamel matrix which ____ calcifies to ____

immediately
~25-30%

21

5. 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

22

6. 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++

23

6. 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)

24

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

25

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

26

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%

27

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

28

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

29

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

30

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