Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ORAL HISTOLOGY AND EMBRYOLOGY > DENTIN > Flashcards

DENTIN Flashcards

1
Q

o greatest bulk of the tooth
o provides general form
o constitutes entire body of
the tooth
o located in both crown and
root

A

DENTIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Physical properties of Dentin

A
  • softer than enamel, harder than bone or root cementum
  • yellowish intrinsic color
  • physically firm, resilient or highly elastic and deformable
    -more radiographically radioluscent than enamel, more radioopaque than pulp
  • positively birefingent - net effect of
    superimposing optically positive collagen fibrils
    and optically negative crystals
  • porous & permeable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Chemical properties of dentin

A

Chemically by weight is:
o approximately 70% organic material
o 20% inorganic material
o 10% water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Inorganic component

A

Hydroxyapatite in
the form of small
plates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Organic component

A

o about 90% collagen
(mainly type I with
small amounts of
types III and V)
o with fractional
inclusions of various
noncollagenous
matrix proteins and
lipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Types of Dentin

A

o Primary
o Secondary
o Tertiary
o Predentin or Dentinoid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

o Regular or Orthodentin
o Developed mostly before eruption
o Contains regularly arranged dentinal tubules
o Dentin formed up until conclusion of growth
o Forms bulk of the tooth

A

PRIMARY DENTIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

▪ the outer thin layer of
primary dentin
▪ the initial dentin formed
▪ 150 µm thick
▪ running parallel with the DEJ
▪ product of young, still
immature odontoblasts or
newly differentiated
odontoblasts
▪ lacks phosphophoryn
▪ slightly (4%) less mineralized

A

MANTLE DENTIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

o develops after root formation
o was once thought to form only in response to
functional stimuli – but found in unerupted teeth
o contains fewer dentinal tubules
o represents the continuing but slower deposition
of dentin after root formation

A

SECONDARY DENTIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

o Reactive, Reparative or Irregular Secondary Dentin
o Formed in response to outside or noxious stimuli:
* attrition, caries,
* erosion, cavity preparation
* therapeutic intervention

A

TERTIARY DENTIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

have vascular inclusion

A

VASODENTIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

similar bone

A

OSTEODENTIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

dentinal tubules are
formed by replacement

A

ATUBULAR DENTIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  • unmineralized or uncalcified dentin matrix
  • variable thickness (10-47 micrometer)
  • lines the innermost (pulpal) portion of the dentin
  • similar to osteoid in bone
  • consists principally of collagen, glycoproteins &
    proteoglycans
A

PREDENTIN or DENTINOID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

 thickest where active dentinogenesis is occurring
 its presence is important in maintaining the integrity
of dentin
 when it is absent the mineralized dentin is vulnerable
to resorption of odontoclasts

A

PREDENTIN or DENTINOID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

 the line of directional change
 the change from primary to
secondary or tertiary dentin
 marked by abrupt changes in
tubular pattern

A

SCHREGER’S LINE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

STRUCTURAL ELEMENTS OF
DENTIN

A
  1. Dentinal Matrix
  2. Dentinal Tubules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

intercellular material of dentin consists of 2
fundamental units

A

Dentinal Matrix

19
Q

2 Fundamental units of the dentinal matrix

A

FORMED ELEMENTS composed of collagenic
UNFORMED ELEMENTS—ground substance

20
Q

imaginary fibers
associated with dentin caused by the silver
staining of ground substances

A

ALPHA OR KORFF”S FIBERS

21
Q

BETA FIBRILS

A

fibrous

22
Q

UNFORMED ELEMENTS—ground substance

A

MUCOPOLYSACCHARIDES

23
Q

Parts of Dentinal Matrix

A

Intratubular Dentin
Intertubular Dentin

24
Q

dentinal matrix that
covers the walls of the
dentinal tubules
* very dense
* has more appatite
crystals per unit volume,
uniformly mineralized

A

Intratubular Dentin

25
Q

dentinal matrix located
between the dentinal
tubules
* the main bulk of the
dentinal material
* less densely mineralized
* noticeably less
radioopaque than
peritubular dentin

A

Intertubular Dentin

26
Q

o inner organic
lining of
calcified tubule
walls
o high in
glucosaminogly
cans (GAG)

A

LAMINA LAMITANS

27
Q
  • cuspal – straighter in
    course
  • proximal of crown – S shaped (crowding of
    odontoblasts)
    o primary curvature –
    coronally
    o secondary curvature
    – apically
  • radicular – right angle
    to long axis
    radicular & cuspal - curvature is
    much less pronounced (less Sshaped)
A

Dentinal Tubules

28
Q

CONTENTS OF THE
DENTINAL TUBULES

A

ODONTOBLASTIC PROCESS S (TOME’S FIBER, DENTINAL FIBER)

PERIODONTOBLASTIC SPACE — DENTINAL FLUID

INTRATUBULAR NERVE
proteoglycans, tenascin, serum albumin, alpha-2 HS, and
transferrin and type V collagen - clearly a complex mixture.

29
Q
  • nonmyelinated nerve fibers of the trigeminal nerve
  • extend up to 0.2 mm from the pulp
  • occlusal dentin - approximately every other tubule
  • pulp chamber – fewer
  • cervical dentin - still fewer
A

INTRATUBULAR NERVE

30
Q

Theories of Dentin Sensitivity

A
  1. TRANSDUCTION THEORY
    2.DIRECT CONDUCTION THEORY
  2. HYDRODYNAMIC THEORY OF
    BRANNSTROM
31
Q

The odontoblastic process mediates the transmission
of stimuli from the periphery of the dentin to the
nerve ending near the pulp

A

. TRANSDUCTION THEORY

32
Q

The nerve endings near the pulp are stimulated
directly

A

DIRECT CONDUCTION THEORY

33
Q

Suggests that transmission of
stimuli is added by a
movement of fluid within the
dentinal tubules or
odontoblastic process

A

HYDRODYNAMIC THEORY OF
BRANNSTROM

34
Q

STRUCTURAL
CHARACTERISTICS OF DENTIN

A
  1. INTERGLOBULAR DENTIN
  2. GRANULAR LAYER OF TOMES
  3. INCREMENTAL LINES OF VON
    EBNER
  4. CONTOUR LINES OF
    OWEN
35
Q
  • area of structural defect where
    unmineralized or
    hypomineralized dentin – fail
    to fuse – homogenous mass
  • most frequent - circumpulpal
  • prevalent in human teeth - a
    deficiency in Vit. D or exposure
    to high levels of fluoride at the
    time of dentinogenesis
A

INTERGLOBULAR DENTIN

36
Q
  • structural defect that
  • comprise uncalcified parts of the
    ground substance
  • appear as dark (black) granules in
    ground section
  • believed due to coalescing and
    looping of the terminal portions
    of the dentinal tubules
  • sensitive area
A

GRANULAR LAYER OF TOMES

37
Q
  • Is the phasic or increment of dentin
    formation at the daily rate
  • approximately 4 micrometers
  • represent the rhythmic process of
    dentinogenesis
  • Run at right angles to the tubules
  • Best seen in longitudinal sections
A

INCREMENTAL LINES OF VON
EBNER

38
Q
  • growth lines in dentin
  • originally referred to a the
    result of a coincidence of
    secondary curvatures of
    dentinal tubules
  • now applied also to
    accentuated lines caused by
    deficiencies in mineralization
  • neonatal line is a prominent
    example
A

CONTOUR LINES OF
OWEN

39
Q

orepresents an
accentuated growth
line that occurs
regularly in
deciduous teeth and
near occlusal
surfaces of
permanent first
molars

A

NEONATAL LINE

40
Q

AGE CHANGES IN DENTIN

A
  1. Sclerotic Dentin or Transparent Dentin
  2. Dead Tracts
41
Q

o Is the morphologic change
o includes thickening of the
peritubular dentin and
o complete obliteration of the
dentinal tubules
o 1
st mesial then distal of root

A

Sclerotic Dentin or Transparent Dentin

42
Q

o Independent of age - can also
become sclerotic in locally
affected areas as a reaction to:
* abrasion
* attrition
* caries
* cavity preparation and
* application of corticosteroids
and filling materials

A

Sclerotic Dentin or Transparent Dentin

43
Q

dentinal tubules are emptied
either by:
* complete refraction of the
odontoblastic processes
from the tubule or
* through the death of
odontoblasts

A

Dead Tracts

44
Q

not seen clinically, only microscopically
* tubules are sealed off – in transmitted
light appear black in ground section
* disintegration may result from:
o Attrition
o erosion
o Abrasion
o caries and
o odontoblastic crowding

A

Dead
Tracts

ORAL HISTOLOGY AND EMBRYOLOGY (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions