Pulp and Cementum (UNIT 4) Flashcards

1
Q

What is the pulp of a tooth derived from?

A

ectomesenchyme of the dental papilla.

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2
Q

Bud stage

A

Dental lamina ectoderm grow into neural crest/ ectomesenchyme.

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3
Q

Cap stage

A

Histodifferentiation.

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4
Q

Bell stage

A

Cytodifferentiation, Morphodifferentiation

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5
Q

Crown stage

A

When hard tissue is laid down: Dentin and then Enamel.

When the Dental Pulp Organ forms from the dental papilla.

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6
Q

What is the only nonmineralized tissue of the tooth?

A

The pulp

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7
Q

What is the texture of pulp tissue?

A

Soft and gelatinous.

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8
Q

How does the size and elasticity of pulp change with age?

A

The pulp is larger and more elastic in young teeth compared to older teeth.

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9
Q

What happens to the pulp as a tooth ages?

A

the pulp is reduced in size by the deposition of secondary dentin.

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10
Q

How is pulp produced during a person’s life?

A
  • produced rapidly during tooth development
  • slowly during adult life
  • and rapidly in response to injury.
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11
Q

How does the volume of pulp vary across different types of teeth?

A

Molars have more pulp than incisors.

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12
Q

What is the formative function of the pulp?

A
  • supports and houses odontoblasts
  • plays a major role in dentin production
  • including the formation of tertiary dentin in response to injury.
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13
Q

What is the sensory function of the pulp?

A

Innervation of the tooth; providing sensory function, including the sensation of pain and temperature changes

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14
Q

What is the nutritive function of the pulp?

A

provides nutrition to all the organic components of the mineralized tissue

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15
Q

What is the defensive function of the pulp?

A

responds to injury and infection through an inflammatory response

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16
Q

What cells are involved in the formative function of the pulp?

A

Odontoblasts
Fibroblasts
Ectomesenchymal stem cells

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17
Q

Which nerve fibers are involved in the sensory function of the pulp?

A

nerve fibers from branches of the trigeminal nerve.

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18
Q

What blood vessels provide nutrition to the pulp?

A

superior and inferior alveolar arteries and veins.

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19
Q

Which cells are involved in the defensive function of the pulp?

A
  • white blood cells (lymphocytes and neutrophils)
  • macrophages
  • mast cells.
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20
Q

What is the role of blood vessels in the pulp?

A

supply nutrients and oxygen to odontoblasts

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21
Q

Through which structure do blood vessels enter and leave the pulp?

A

via the apical foramen

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22
Q

which structure does the pulp share blood supply with?

A

the periodontium, which can allow bacterial infections to spread from the periodontal ligament.

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23
Q

What is the role of unmyelinated C fibers in the pulp?

A
  • respond to inflammation and toxins
  • causing prolonged, dull/aching, poorly localized pain that lasts longer than the applied stimulus.
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24
Q

What is the role of myelinated fibers (Alpha type) in the pulp?

A
  • extend into the dentinal tubules
  • give rise to brief, sharp, well-localized pain in response to thermal, evaporative, tactile, osmotic, or chemical stimuli.
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25
Q

Why is the sensory innervation of the pulp important during cavity preparation?

A

is why analgesics (pain relievers) are necessary during cavity preparation to manage pulpal pain.

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26
Q

How can pulp inflammation affect the pain felt by the patient?

A

can be extremely painful or have no associated pain, depending on the state of the nerves within the pulp.

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27
Q

What happens to the tooth if the pulp becomes necrotic and how does it appear?

A
  • the presence of dead tracts in the dentin, caused by the death of odontoblasts.
  • the crown of the tooth may appear darker
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28
Q

What do the unmyelinated Autonomic supply?

A

smooth muscle of the blood vessels to regulate blood flow.

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29
Q

Where is the coronal pulp located?

A

in the crown of the tooth.

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30
Q

What structures may the coronal pulp contain?

A

a roof, pulp horns, and a floor.

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31
Q

Where is the radicular pulp located?

A

in the root canal of the tooth.

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32
Q

What is the shape of the radicular pulp?

A

tube-shaped.

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33
Q

How is the radicular pulp connected to the periodontal connective tissue?

A

it is continuous with the periodontal connective tissue at the apical foramen.

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34
Q

What is the function of the odontoblastic layer in the pulp?

A

Synthesize and secrete dentin

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35
Q

Does the odontoblastic layer have sensory nerves?

A

Yes

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36
Q

What happens in the odontoblastic layer in response to bacterial toxins?

A

Produce pro-inflammatory mediators

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37
Q

Where is the cell-free zone (of Weil) located?

A

in the coronal pulp.

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38
Q

What is found in the cell-free zone (of Weil)?

A
  • extracellular matrix
  • nerve fibers
  • capillaries
  • tissue fluid
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39
Q

What types of cells are found in the cell-rich zone of the pulp?

A

fibroblasts and ectomesenchymal stem cells, which can differentiate into odontoblasts.

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40
Q

What structure is found in the cell-rich zone besides cells?

A

Nerve plexus

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41
Q

What is the pulp core?

A

bulk of the pulp and is continuous with the periodontal ligament (PDL).

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42
Q

What type of connective tissue is found in the pulp core?

A

loose connective tissue with:
- fibroblasts
- macrophages
- mast cells
- white blood cells
- fibers
- ground substance
- progenitor cells.

43
Q

What important structures are found in the pulp core?

A

blood vasculature and nerves

44
Q

What are true denticles composed of?

A

dentin

45
Q

How do odontoblasts contribute to true denticles?

A

differentiate within the pulp and produce dentin

46
Q

What induces the formation of pulp stones?

A

by remnants of Hertwig’s root sheath being trapped in the pulp.

47
Q

How common are pulp stones?

A

rare

48
Q

What are false denticles?

A

concentric layers of calcified tissue that form around foci of dead cells or collagen bundles, not dentin.

49
Q

What are diffuse calcifications?

A

irregular shaped calcifications of connective tissue collagen (not dentin)

50
Q

When do pulp stones become clinically significant?

A

if they block access to the full pulp chamber during a root canal treatment.

51
Q

What is cementum, and where is it located?

A

the hard tissue layer on the outer aspect of the root of the tooth.

52
Q

What is the organic matrix of cementum called

A

cementoid

53
Q

What percentage of cementum is organic matrix?

A

50% of cementum.

54
Q

what does the organic matrix of the cementum contain?

A

water
proteins: primarily collagen type I

55
Q

What is the inorganic component of cementum

A

hydroxyapatite

56
Q

What percentage of cementum is inorganic matrix?

A

50% of cementum.

57
Q

What is the primary function of cementum?

A

anchors teeth into their sockets by attaching to the periodontal ligament.

58
Q

How does cementum protect the tooth structure?

A

seals the ends of the dentinal tubules

59
Q

How does cementum aid in the repair of the tooth?

A

allows repair along the root surface

60
Q

Why is cementum important in orthodontics?

A

permits orthodontic movement

61
Q

How does cementum differ from bone regarding resorption?

A

Cementum is more resistant to resorption than bone

62
Q

When does root formation begin during tooth development?

A

when enamel and dentin formation reach the cervical loop, marking the end of the crown stage.

63
Q

What is the cervical loop?

A

is the reflection of the outer enamel epithelium onto the inner enamel epithelium. Lacks stratum intermedium

64
Q

How does the cervical loop contribute to root development?

A

it elongates inferiorly to initiate and guide root formation.

65
Q

What happens to the inner enamel epithelium (IEE) without the stratum intermedium?

A

the inner enamel epithelium (IEE) cannot differentiate into pre-ameloblasts

66
Q

How do cementoblasts form and what is their function?

A

Ectomesenchymal cells from the dental sac migrate to the dentinal surface and differentiate into cementoblasts, which secrete cementum to cover the root.

67
Q

What factors influence the formation of the Cemento-Enamel Junction (CEJ)?

A

involves the timely breakdown of Hertwig’s Epithelial Root Sheath and may be affected by the degeneration of the Reduced Enamel Epithelium.

68
Q

What characterizes the “classical” CEJ junction, and how is it formed?

A
  • occurs in 30% of cases
  • involves the perfect timing of the breakdown of Hertwig’s Epithelial Root Sheath, allowing ectomesenchymal cells to form cementoblasts that create cementum.
69
Q

What causes cementum and enamel not to meet at the CEJ in 10% of cases?

A

a delayed breakdown of Hertwig’s epithelial root sheath persists below the CEJ junction, delaying cementum formation

70
Q

What causes cementum to overlap enamel in 60% of cases?

A

premature breakdown of the Hertwig’s epithelial root sheath (HERS) at the cervix allows dental sac (follicle) cells to reach the enamel, forming cementoblasts and causing early deposition of cementum over enamel.

71
Q

Where do cementoblasts originate from?

A

from dental sac (follicle) cells.

72
Q

Where are cementoblasts found

A

on the surface of cementum

73
Q

what is the role of cementoblasts?

A

responsible for laying down the organic matrix (cementoid) on the surface of root dentin.

74
Q

What are cementocytes, and how do they form?

A

Cementocytes are cementoblasts that become embedded in cementum during its formation.

75
Q

Where do cementocytes originate from?

A

derived from dental sac cells.

76
Q

Where are cementocytes housed?

A

are housed in hollow spaces within the cementum called lacunae.

77
Q

What is the function of the processes in cementocytes?

A

extend toward the periodontal space to facilitate communication and nutrient exchange.

78
Q

What is the function of cementoclasts?

A

demineralize and remove cementum.

79
Q

What is the structure of cementoclasts?

A

large, multinucleated cells.

80
Q

Where do cementoclasts originate from?

A

derived from monocytes.

81
Q

Which other cell type do cementoclasts resemble?

A

resemble osteoclasts, which remove bone tissue.

82
Q

Where are cementoclasts found?

A

found on the surface of cementum.

83
Q

what are the two types of cementum?

A

acellular and cellular

84
Q

what is acellular cementum?

A

has no cells within its calcified matrix.

85
Q

what is cellular cementum?

A

contains cells (cementocytes) within its calcified matrix

86
Q

Where is acellular cementum primarily located on the root?

A

found on the cervical two-thirds of the root.

87
Q

When is acellular cementum formed?

A

it is the first type of cementum made during tooth development.

88
Q

Where is cellular cementum primarily located on the root?

A

found on the apical one-third of the root.

89
Q

is cellular cementum thicker or thinner than acellular cementum?

A

thicker than acellular

90
Q

How does cellular cementum change over time?

A

grows gradually throughout life.

91
Q

What are Sharpey’s fibers, and how do they form?

A

are collagen fibers secreted by fibroblasts in the dental sac that become trapped in the newly-formed cementoid.

92
Q

Are Sharpey’s fibers part of the cementoid matrix?

A

No, Sharpey’s fibers are not true matrix fibers; they are part of the periodontal ligament.

93
Q

What is the role of Sharpey’s fibers?

A

they are the terminal ends of collagen fibers that extend between the cementum and alveolar bone to anchor the tooth in its socket.

94
Q

What are resting lines in cementum?

A

they are growth lines in cementum that demarcate daily growth patterns.

95
Q

Where are resting lines most prominent?

A

most prominent in the apical one-third of the tooth, where cellular cementum is located.

96
Q

How do resting lines differ in acellular and cellular cementum?

A

In acellular cementum, resting lines are closer together, while in cellular cementum, they are further apart.

97
Q

What are lamellae in cementum?

A

they are thicker bands in cementum

98
Q

when do lamellae form?

A

it forms during times of force or trauma, indicating new cementum deposition as part of remodeling

99
Q

What are cementicles?

A

areas of calcified tissue that are embedded in or floating near the cementum.

100
Q

What factors can induce the formation of cementicles?

A
  • Hertwig’s epithelial root sheath
  • mineralized Sharpey’s fibers
  • local trauma
  • hyperactivity
  • age
101
Q

Where can cementicles be located?

A
  • periodontal ligament
  • on the surface of cementum
  • embedded within cementum.
102
Q

What are enamel pearls?

A

they are remnants of the dental lamina or inner enamel epithelium (IEE) that may trap some stratum intermedium and can differentiate to form ameloblasts at the cervical region of the tooth.

103
Q

How do enamel pearls form enamel?

A

The remnants of the dental lamina or IEE give rise to ameloblasts, which produce enamel at the cervical region of the tooth.