Oral Cavity and Tooth development -Part 2 Flashcards

1
Q

what are teeth grossly divided into

A

root and crown

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2
Q

what is the tooth root

A

portion of tooth embedded in bone

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3
Q

where is the tooth root located

A

in part of the jaw called alveolar ridge, in the tooth socket called the alveolus

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4
Q

what is the crown

A

the portion of the tooth that projects into oral cavity

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5
Q

what is the enamel

A

a highly mineralized layer that protects the crown

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6
Q

describe enamel

A

hard, translucent substance, containing less than 1% organic material and 96-98% hydroxyapatite

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7
Q

what does enamel derive from embryologically

A

ectoderm

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8
Q

what is enamel secreted by

A

tall, columnar ameloblasts of enamel organ

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9
Q

what are tome’s processes

A

apical, secretory end of ameloblast

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10
Q

what is the formation of enamel rods due to

A

enamel mineralization not being uniform

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11
Q

what are enamel rods separated by

A

interprismatic material

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12
Q

where do enamel rods extend from

A

ameloblasts at enamel surface to dentino-enamel junction

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13
Q

what is dentin embryologically derived from

A

mesoderm

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14
Q

what is the bulk of the tooth composed of

A

dentin

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15
Q

what secretes dentin

A

odontoblasts of dental papilla as non-mineralized pre-dentin

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16
Q

what is dentin chemically similar to

A

bone but more mineralized ~70% hydroxyapatite crystals

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17
Q

what does dentin contain

A

type 1 collagen and GAGs

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18
Q

what is dentin arranged in

A

dentin tubules

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19
Q

what do dentin tubules radiate from

A

pulp cavity

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20
Q

what do dentine tubules contain

A

long rod-like cytoplasmic processes of odontoblasts (Tome’s processes)

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21
Q

what does the pulp cavity contain

A

support structures such as sensory nerves and blood vessels

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22
Q

what is dentin innervated by

A

myelinated nerves

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23
Q

what is dental pulp embryologically derived from

A

mesoderm

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24
Q

what does dental pulp resemble

A

primitive mesenchyme

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25
Q

what does dental pulp contain

A

stellate fibroblasts, reticular fibers, collagen and ground substance

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26
Q

what is dental pulp supplied by

A

capillaries from arterioles running with periodontal ligament

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27
Q

what is the tooth root covered by

A

a thin layer of cementum

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28
Q

what is cementum embryologically derived from

A

mesoderm

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29
Q

what is cementum

A

amorphous, collagen-based, calcified tissue ~45-50% hydroxyapatite, similar to bone

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30
Q

what makes cementum

A

cementoblasts that mature into cementocytes

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31
Q

what are cementoblasts/cementocytes similar to

A

osteoblasts/osteocytes

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32
Q

what anchors the cementum layer to bone of alveolus

A

fibers of periodontal ligament or membrane

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33
Q

what is the periodontal ligament composed of

A

dense, collagenous fibers called sharpeys fibers

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34
Q

what do sharpeys fibers do

A

run at an oblique angle to support tooth in socket and allow slight movement of tooth during mastication

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35
Q

what are epithelial rests of Malassez

A

occasional clusters of epithelial cells within periodontal ligament

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36
Q

what is the neck of the tooth

A

the region of tooth between root and crown

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37
Q

what protects the gingiva

A

masticatory oral mucosa

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38
Q

what does the gingiva cover

A

upper portion of alveolar ridge

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39
Q

what does attached gingiva cover

A

upper alveolar bone

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40
Q

what does free gingiva form

A

cuff or neck of tooth

41
Q

what is the space between the free gingiva and crown called

A

gingival sulcus or crevice

42
Q

what the gingival sulcus lined by

A

crevicular epithelium

43
Q

what is the periodontium

A

tissues that surround and support tooth

44
Q

what does the periodontium include

A

epithelium, cementum, periodontal ligament and alveolar bone

45
Q

what 2 opposing layers form the tooth and what is their origin

A

ameloblasts of enamel organ and odontoblasts of dental papilla

46
Q

what tooth structures are derived from ectoderm

A

enamel

47
Q

what tooth structures are derived from mesoderm

A

dentin, cementum, pulp, and periodontal ligament

48
Q

what happens in the 6th week of fetal development

A

a horseshoe shaped epithelial ridge arises from oral epithelium which forms the dental lamina in position of future jaws

49
Q

what forms in each quadrant

A

lamina develops globular, ectodermal swellings ( one for each deciduous tooth) -> superficial half forms enamel organs and deep half forms dental papilla

50
Q

what happens in the cap stage

A

enamel organ initially cup shaped

51
Q

what do the cells of enamel organ progressively differentiate into

A

stellate reticulum with ECM of GAGs

52
Q

what comes after the cap stage

A

bell stage

53
Q

what do the cells lining the outer convex surface of the enamel organ become in the bell stage

A

external enamel epithelium

54
Q

what do the cells lining concave surfaces of the enamel organ form in the bell stage

A

internal enamel epithelium that differentiate into tall columnar ameloblasts

55
Q

what is amelogenesis

A

enamel formation

56
Q

where is the dental papilla located

A

deep to developing enamel organs

57
Q

what do cells lining convex surface of dental papilla develop into

A

odontoblasts

58
Q

what is dentinogenesis

A

dentin formation

59
Q

what does the development of ameloblasts induce

A

differentiaition of odontoblasts

60
Q

what does calcification of dentin induce

A

deposition of enamel

61
Q

what is tooth formation initiated by

A

deposition of organic pre-dentin by odontoblasts on surface of dental papilla that is later calcified into dentin

62
Q

what does the calcification of dentin matrix secondarily induce

A

enamel production by ameloblasts

63
Q

where are odontoblasts processes located

A

embedded in dentin matrix to form dentin tubules

64
Q

what does enamel form in and what is it separated by

A

forms in mineralized columns of enamel rods separated by less mineralized interprismatic material

65
Q

what happens after the deposit of dentin and enamel

A

dental lamina fragments and atrophies

66
Q

what happens at tooth eruption to enamel organ and ameloblasts

A

they degenerate

67
Q

what separates as the tooth erupts

A

overlying mucosa

68
Q

what does the dental papilla become as it shrinks

A

dental pulp surrounded by dentin

69
Q

what continues to be produced after tooth formation is complete

A

small amounts of secondary dentin

70
Q

what determines the 3D shape of the tooth crown

A

overall shape of enamel organ

71
Q

what is the epithelial sheath of Hertwig

A

outer rim of enamel organ

72
Q

what does the epithelial sheath of Hertwig determine

A

cross sectional outline of tooth

73
Q

what does the surrounding mesenchyme form

A

dental follicle -> periodontal ligament

74
Q

what do enamel organs of permanent teeth develop as buds from

A

dental lamina and deciduous enamel organ

75
Q

what does the dental lamina proliferate as in molars

A

caudally to form enamel organs of secondary dentition

76
Q

when does tooth development begin

A

at 6th week of fetal development

77
Q

how many roots do incisors and canines have

A

1 root

78
Q

how many roots do premolars usually have

A

2 roots

79
Q

how many roots do molars usually have

A

2-4 roots

80
Q

when should you not prescribe tetracycline and why

A

during development of permanent dentition because it causes yellow discoloration of teeth

81
Q

do molars have precursors

A

no

82
Q

what is the human dental formula

A

I 2/2, C 1/1, P 2/2, M 3/3

83
Q

what are incisors function

A

cutting and biting

84
Q

what is canine function

A

puncturing and holding

85
Q

what are premolars and molars used for

A

grinding

86
Q

what does TMJ allow for

A

lateral and anterior-posterior motion important for chewing and grinding

87
Q

what are cusps

A

raised points on occlusal surfaces of molars and premolars

88
Q

what are the types of cusps

A

protocone, metacone and paracone

89
Q

what is talonid

A

flattened posterior surface of lower molars

90
Q

what is bunodont

A

low crowned premolars and molars in omnivores

91
Q

what is hypsodont

A

tall and high crowned premolars and molars in herbivores

92
Q

what is orthodontia accomplished by

A

osteoblast and osteoclast activity in alveolus

93
Q

what are dental caries

A

results when weak acids in food and drink erode calcified enamel augmented by bacterial infection

94
Q

what does fluoride do

A

hardens enamel and kills bacteria

95
Q

what is a root canal

A

when caries extend into dentin or pulp cavity to produce abscesses or death of tooth

96
Q

what is periodontal disease caused by

A

accumulation of calcified food and bacterial debris (plaque) in gingival sulcus that results in widening of gingival sulcus, possible inflammation and destruction of periodontal ligament

97
Q

what is gingivitis

A

inflammation of gums

98
Q

what is periodontitis

A

inflammation of periodontal ligament