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CUSOD Oral Histology > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

what is the primary epithelial band? what does it become?

A

thickened epithelium that becomes dental lamina and vestibular lamina

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2
Q

what initiates tooth formation

A

dental epithelium initiates tooth formation (requires ectomesenchyme to progress to later stages)

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3
Q

characteristic event of initiation stage

A

epithelial band splits.
dental lamina invaginates and forms lingual side
vestibule lamina forms invaginates and forms a trough labially

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4
Q

what demarcates the initial site of each tooth bud forming in the oral cavity

A

dental lamina

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5
Q

beginning at the ___, the ectomesenchyme determine the type of tooth formed and directs morphogenesis of the tooth

A

bud stage

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6
Q

what condenses and surrounds epithelial bud at bud stage

A

ectomesenchyme

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7
Q

what causes tooth bud epithelium to proliferate and epithelium to fold

A

signaling from ectomesenchyme

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8
Q

what leads to change of bud shape

A

folding of epithelium occurring closest to ectomesenchyme (leads to cap stage)

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9
Q

Cap stage functional stage

A

morphogenesis - process of changing tooth shape due to folding of epithelium

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10
Q

what directs folding and shape changes of enamel organ?

A

aka morphogenesis directed by ectomesenchyme

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11
Q

when is tooth germ first recognized

A

early cap

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12
Q

early cap: proliferation and folding of epithelium of tooth bud (oral ectoderm) becomes what?

A

enamel (dental) organ

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13
Q

early cap: ectomesenchyme condensing beneath tooth bud becomes?

A

dental papilla

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14
Q

early cap: condensation of ectomesenchyme surrounding the outside of tooth bud and papilla becomes?

A

dental follicle/sac

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15
Q

when does enamel knot appear?

A

begins at end of bud thru late cap
best visualized in late cap

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16
Q

what stage:
enamel organ has shape of a cap with convex and concave border; cap sits on a ball of ectomesenchyme

A

early cap

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17
Q

when is a tooth germ comprised of the following three structures first visible: enamel organ, dental papilla, and dental follicle?

A

early cap

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18
Q

characteristic events of late cap stage

A
  • dental epithelium of enamel organ aggregates to form enamel knot
  • primary enamel knot located close to ectomesenchyme of dental papilla
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19
Q

what is the primary enamel knot?

A

signaling center that causes both enamel organ and dental papilla to differentiate into specific cells

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20
Q

when does the primary enamel knot undergo apoptosis

A

end of cap stage

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21
Q

what regulates tooth shape, size of crown and cusp formation by controlling proliferation and differentiation of enamel organ and dental papilla

A

primary enamel knot

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22
Q

what morphological stage: differentiation - enamel organ and dental papillae differentiate into specific cell types (cytodifferentiation)

A

bell stage

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23
Q

characteristic events of early bell stage

A
  1. tooth germ differentiation (enamel organ becomes 4 layers)
  2. cervical loop is visible
  3. secondary enamel knot visible for multi0cusped teeth
  4. dental papilla starts to differentiate into pre-odontoblasts to odontoblasts
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24
Q

what are the 4 epithelial layers first visible at early bell

A

OEE, stellate reticulum, stratum intermedium, and IEE

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25
Q

what secretes alkaline phosphatase needed for mineralization

A

stratum intermedium

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26
Q

what stage is this:
enamel organ shape of bell with convex and concave border; four cell layers are visible. Cervical loop visible, dental papilla enclosed within the concavity of the enamel organ. Dental follicle is visible surrounding convex surface

A

early bell

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27
Q

what is a characteristic event of late bell

A

cusp formation (dentinogenesis = denttin deposition)

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28
Q

cusp formation at late bell leads to?

A
  1. maturation of IEE to ameloblasts
  2. differentiation of odontoblasts
  3. deposition of the unmineralized predentin matrix from odontoblast in region of cusp (will mineralize into dentin)
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29
Q

first site of IEE maturation is where? least mature is where?

A

first site: cusp tips
least mature: down at cervical loop and between cusps

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30
Q

where are undifferentiated pre-odontoblasts closest to?

A

cervical loop region

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31
Q

secondary enamel knots appear only where?

A

multi-cusped teeth - located at tips of future cusps that serve as signaling center

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32
Q

where does cusp formation occur in single cusp teeth

A

where primary knot was initially located

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33
Q

how does future pulp chamber form

A

cervical loop elongates due to growth/folding of cusps and encloses the dental papilla

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34
Q

the tooth loses contact with oral cavity as what happens?

A

as dental lamina degenerates

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35
Q

at late bell, the dental follicle remains _ until root forms

A

undifferentiated

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36
Q

at late bell, _ is visible lingual to anterior primary teeth

A

successional lamina

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37
Q

in ___, predentin is deposited and the dentin matrix is beginning to mineralize but enamel has not yet been formed

A

late bell

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38
Q

__ formation precedes __ deposition

A

dentin formation precedes enamel deposition

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39
Q

late bell: signals from enamel knot cause

A
  1. ameloblasts begin to differentiate first from the enamel organ at level of cusp - no enamel secreted yet
  2. odontoblasts mature and differentiates from dental papilla at level of cusp -> predentin deposition and dentin mineralization begins
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40
Q

cells of dental papilla closest to _ in enamel organ differentiate into mature odontoblasts

A

closest to ameloblasts

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41
Q

odontoblast maturation shape change

A

cuboidal -> columnar cell with odontoblastic process on apical surface of odontoblast

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42
Q

function of mature odontoblasts

A
  1. synthesize and secretes daily increments of predentin matrix
  2. odontoblastic processes facilitate mineralization of dentin after predentin deposited
  3. mineralization occurs around odontoblastic process forming dentin tubule
  4. odontoblasts move toward pulp with successive increments of denin matrix
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43
Q

what forms dentin tubule

A

mineralization of odontoblast around the odontoblastic processes

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44
Q

when is predentin first deposited? where?

A

first deposited in late bell
in area adjacent to ameloblasts (future DEJ) at futue cusp

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45
Q

what is always located along pulp border between dentin and odontoblasts? what is it comprised of?

A

predentin unmineralized organic matrix always located there

comprised of type I collage and organic dentin specific proteins (for scaffolding of hydroxyapatite)

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46
Q

what does incremental mineralization of pre-dentin matrix mean?

A

following predentin mineralization, dentin mineralization begins 24 hours after
- involves deposition and coalescing of hydroxyapatite crystal
- following mineralization, new layer of pre dentin deposited

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47
Q

what causes terminal differentiation and maturation of immature into secretory ameloblasts in cusps?

A

presence of dentin matrix and signaling from odontoblasts

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48
Q

__ and __ deposition continues for the life of the tooth - deposited in crown and root

A

predentin and dentin

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49
Q

two regions of dentin in crown

A
  1. mantle dentin - closest to DEJ of cusps, first mineralized
  2. circumpulpal dentin - bulk of dentin found in crown lies closest to predentin/pulp
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50
Q

what occurs in appositional stage

A

enamel and dentin deposited incrementally in successive layers

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51
Q

what occurs during crown stage

A
  1. deposition of hard tissue begins at DEJ of cusps before continuing towards cervix/cervical loop
  2. enamel and dentin deposited simultaneously
  3. ameloblasts are at different stages of maturation
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52
Q

what initiates crown stage

A

immature ameloblasts mature into secretory ameloblasts and begin to deposit partially mineralized enamel matrix along DEJ at future cusp

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53
Q

what triggers ameloblast to terminally differentiate into secretory ameloblasts at the future cusps

A

presence of dentin matrix and signaling from odontoblast

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54
Q

what are the stages of ameloblast differentiation

A
  1. pre-secretory (inductive stage)
  2. secretory stage
  3. maturation stage
  4. protective stage
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55
Q

what is the pre-secretory stage of ameloblast differentiation

A
  • aka inductive stage (occurs during crown stage)
  • goes from cuboidal to columnar
  • cell is polarized (apex and base)
  • terminally differentiated
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56
Q

what is the secretory stage of ameloblast differentiation

A

two types of columnar polarized cell
1. no tomes process
2. tomes process on apical surface to determine orientation of enamel crystals

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57
Q

what is the maturation stage of ameloblast differentiation

A

removal of water/organic ECM; final mineralization
ruffled and smooth

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58
Q

what is the protective stage of ameloblast differentiation

A

ameloblasts become cuboidal again and fuses with remnants of enamel organ

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59
Q

where are immature IEE cells usually found

A

at cervical loop and intercuspal region of multicusped teeth

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60
Q

what are the cells involved in amelogenesis

A
  1. secretory ameloblast
  2. maturational ameloblast
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61
Q

steps of amelogenesis

A
  1. secretory stage > partial mineralization of enamel into crysals (begins early crown stage and continues until full thickness deposited in a region)
  2. maturation stage > pattern follows secretion, final maturation of enamel matrix increases hydroxyapatite and removes organic matrix
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62
Q

types of secretory ameloblast? function?

A

with and without tomes process
fn: synthesize organic ECM and partially mineralize matrix at time of deposition

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63
Q

ameloblast secrete unique enamel matrix proteins. describe these proteins

A
  • no collagen
  • two classes: amelogenin proteins (90%) and non-amelogenin (10%)
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64
Q

steps of enamel secretion

A
  1. ameloblast synthesizes unique enamel matrix proteins
  2. partial mineralization of enamel
  3. maturation stage
  4. protective stage
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65
Q

three orientations of enamel crystals

A
  1. aprismatic/structureless - enamel crystals deposited parallel to each other and perpendiculr to surface (tightly packed). located at initial layer of DEJ and final layer on outer surface
  2. prismatic - rod
  3. inter-prismatic - interrod, located at bulk of crown
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66
Q

describe aprismatic enamel on surface of tooth

A

crystals are well aligned and tightly packed, so minimal organic ECM

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67
Q

outcome of aprismatic enamel

A

highly mineralized, less porous = better caries protection when compared to subsurface enamel

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68
Q

cells involved in maturation stage

A
  1. ruffled mature ameloblasts - enamel increases in mineral content
  2. smooth mature ameloblasts - removal of water and organic proteins from the enamel by enzymatic digestion
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69
Q

outcome of maturation stage

A

increased mineral content
- achieved by enzymatic removal and degrading most of organic ECM originally deposited and increasing mineral content
- increasin crystal size by increasing width and amount of hydroxyapatite comprising enamel matrix

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70
Q

what percent of immature enamel is mineralized at time of secretion

A

25-30%

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71
Q

mature enamel contains how much hydroxyapaptite, water, and organic ECM

A

96% HAP
3% water
1% ECM

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72
Q

failure to deposit adequate HAP leads to

A

hypocalcified enamel

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73
Q

failure to remove water and organic proteins leads to

A

hypomature/immature enamel

can also occur due to defects in enzymes necessary for organic matrix removal

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74
Q

how are all hard tissue deposited?

A

incrementally in successive layers by appositional growth

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75
Q

incremental lines in enamel are

A

Stria of Retzius

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76
Q

incremental lines in dentin are

A

Contour lines of Owen

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77
Q

what can arise when a given antibiotic causes permanent stain in teeth undergoing crown development?

A

tetracycline bands

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78
Q

cells involved in protective stage of amelogenesis

A

protective ameloblast (post-maturational cells)

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79
Q

characteristic events during protective stage of amelogenesis

A
  • protective ameloblasts are flattened squamous cells without tomes process
  • adhere to final layer of enamel
  • contributes to formation of REE
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80
Q

what is REE

A

reduced enamel epithelium also called Nasmyth’s membrane or developmental enamel cuticl

during eruption, fuses with oral epithelium to form junctional epithelium

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81
Q

what happens to the remaining cells of enamel organ following mineralization?

A

SI, SR, and OEE collapse and fuse with layer of protective ameloblasts to form REE

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82
Q

what structure signifies end of crown and start of root formation

A

Hertwig’s epithelial root sheath - structure formed by fused cervical loop

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83
Q

devlopment of deciduous tooth crown extends from when to when?

A

4th month of gestation to approcimately 12 months

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84
Q

development of crowns on permanent teeth extends from when to when

A

begins around five (first molars) with completion of all permanent at approximately 8 years (3rd molar exception at 16 years)

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85
Q

when will roots form following crown formation

A

primary - roots complete 1.5 years after emergence into oral cavity
permanent - root complete 3.5 years after emergence into oral cavity

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86
Q

what is the mechanism controlling root development

A

inductive signaling b/w HERS and dental papilla and dental follicle (ectomesenchyme derived)

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87
Q

differentiation of dental follicle into the periodontium (alveolar bone, PDL, cementum) depends on what/

A

root development

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88
Q

what are the general stages of root development and approximately how much of root is developed?

A
  1. root initiatiion
  2. early root (1/4 root)
  3. mid root (2/3 root, begins to erupt)
  4. latte root (3/4 root, still erupting, not yet in occlusion)
  5. root complete (after tooth in functional occlusion, apical foramen narrowed by dentin/secondary cementum)
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89
Q

what initiates root formation

A

crown completion and development of HERS

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90
Q

what is the function of HERS

A

HERS grows apically between papilla and dental follicle to elongate the root and delineate root shape and guide root growth.
Function: guide root growth

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91
Q

what is epithelial diaphragm

A

Epithelial diaphragm (ED) is the free bottom edge of HERS grows inward below the dental papillae and encloses the primary apical foramen.

Function: Differential growth of the ED determines final shape and number of roots

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92
Q

in multirooted teeth, what determines root numberr

A

differential growth and invagination of ED

causes ED to grow together at specific points to form furcation zone/point

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93
Q

steps of root formation

A
  1. HERS develops from cervical loop of enamel organ
  2. HERS induces odontoblast differentiation
  3. deposition of predentin/dentin
  4. dentin induces fragmentation of HERS
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94
Q

___ of HERS induces odontoblast differentiation

A

IEE epithelial cells of HERS

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95
Q

what type of dentin lies adjacent to HERS during deposition

A

mineralized radicular dentin

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96
Q

dentin in root is sometimes called ___.
dentin in crown is called ___.
all dentin deposited in crown and root prior to entering occlusion is classified as ___.

A

radicular dentin
coronal dentin
primary dentin

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97
Q

when does HERS move away from root surface and break down

A

after primary radicular dentin is deposited in root (due to programmed cell death)

98
Q

what is a remnant of HERS that forms clusters of epithelial cells

A

epithelial cell rests (ectoderm derived)
**the only epithelial derived structure found in PDL

99
Q

function of ECRs

A
  1. maintains PDL homeostasis/turnoverr
  2. maintains periodontal space -> prevents ankylosis; prevents root resorption
  3. maintains orthodontic movements
100
Q

structures formed during dental follicle differentiation

A
  1. cementum
  2. PDL
  3. alveolar bone
101
Q

principal cell types during dental follicle differentiation

A
  1. inner layer > cementoblasts > cementum
  2. middle layer > fibroblasts > PDL
  3. outer layer > osteoblasts > alveolar bone
102
Q

___ forms the supporting structures
and is induced to differentiate during root
formation by cells of HERS/ECR and the presence
of dentin and dental papilla

A

dental follicle

103
Q

during bud to crown stage, the dental follicle is ___

A

undifferentiated

104
Q

At this early root stage, radicular (root) dentin has stimulated HERS to _.

A

start to break down near cervix but remains still intact apically.

105
Q

Acellular (primary) cementum deposition first occurs in ___. When deposition begins it will occur closest to crown (cementum has not yet been
begun in this section).

A

early root

106
Q

cementum composition

A

40-50% HAP
50% organic matrix (requires alkaline phosphatase for mineralization)

107
Q

cementum functiton

A

protect dentin-pulp complex
anchor tooth to alveolar bone via PDL
adapt for occlusal wear once tooth in occlusion

108
Q

When and where is cementum first deposited

A

in early root stage beginning in region of tooth cervix and establishes CEJ junction

109
Q

cementoblasts continue to differentiate and deposit primary acellular extrinsic fiber cementum until when? where is it deposited?

A

until tooth enters occlusion in late root.
this type of cementum deposited in cervical 2/3 of root.

110
Q

3 types of cementum in adult root

A
  1. primary acellular extrinsic fiber cementum - early, mid, late
  2. secondary cellular intrinsic fiber - late, root completion
  3. secondary mixed fiber cementum - during late and root complete (combination of above two)
111
Q

potential pattern of cementum deposition in early root

A
  1. cementum overlaps enamel and deposited in crown
  2. enamel and cementum meet at cervix
  3. gap exists between cementum and enamel
112
Q

what causes cementum to overlap enamel and become deposited into crown?

A

if REE covering enamel breaks, and exposes enamel. the cementum lacks collagen (afibrillar)

113
Q

what causes a gap between cementum and enamel?

A

if there is a delay in breakdown and movement of HERS away from dentin surface

114
Q

what establishes the cementum-dentin junction?

A

cementoblasts in contact with dentin and secrete unmineralized matrix cementum (aka cementoid)

CDJ can also be called intermediate cementum

115
Q

PDL fibers differentiate from dental follicle and become embedded in cementum. What are these fibers now called?

A

sharpey’s fibers

these PDL fibers mature once in occlusion

116
Q

what type of deposition does primary acellular cementum exhibit? why?

A

slow deposition prior to eruption. this allows PDL fibers to become trapped within cementum

117
Q

what forms the main anchor for the tooth in the jaw

A

sharpey’s fibers inserted into primary cementum

118
Q

principal cell of PDL

A

fibroblast
- intermediate layer of follicle differentiates into fibroblast
- otherr cell types present including stem cells

119
Q

ECM of PDL

A

collagen fibers and non-collagenous proteins deposited between cementum and alveolar bone

organic matrix: collagen (I, III, XII) and oxytalan (elastic)
synthesis of collagen depends on vitamin C

120
Q

function of PDL

A

tooth attachment and adaptive response to occlusal load

121
Q

PDL fiber function

A

serve to attch primary acellular cementum to bone

Collagen fibers synthesized by fibroblasts in PDL become embedded in primary cementum-fibers are known as extrinsic fibers (acellular extrinsic fiber cementum)

Distinct bundles of PDL, known as principal fiber group, are not recognized until tooth erupts in the oral cavity and in occlusion

122
Q

principal fiber group

A

bundles of PDL not recognized until tooth erupts in oral cavity and in occlusion

123
Q

PDL attachment

A

point of fiber attachment to bone and cementum via Sharpey’s fibers

124
Q

principal cell type of alveolar process

A

osteoblasts - differentiate from outer layer of dental follicle

125
Q

what stimulates alveolar process development

A

depends on tooth development and eruption
stress helps maintain structure

126
Q

during root formation, what does the alveolar process form?

A

labial and lingual bone

127
Q

increased bone deposition forms a __ around the tooth and the __ separates adjacent teeth

A

crypt; interdental septum

128
Q

two regions of jaw bone

A
  1. basal bone - body of mandible or maxilla
  2. alveolar process - stimulated to develop when tooth is present
129
Q

what is the tooth socket also called

A

alveolar bone proper

130
Q

types of hard tissue deposited in late root thru post-eruption/occlusion

A
  1. formation of secondary dentin - dentin continues to be deposited throughout life of tooth
  2. secondary cementum - two types occurs after tooth erupts and is in occlusion along apical 1/3 of root
131
Q

types of secondary cementum

A
  1. secondary intrinsic cellular fiber cementum
    - formed once tooth in occlusion
    - cementoctyes trapped within this matrix also synthesize collagen fibers
    - location: mid to apical 1/3 and interradicular
    - function: repair and adaption to occlusal wear
  2. secondary cellular mixed fiber cementum
    - mix of cellular intrinsic and acellular extrinsic found once in occlusion to adapt to occlusal wear
    - near apical third to apex of tooth and furcation
    - function: adaption to occlusal wear, ANCHORAGE, and aids in repair
132
Q

two regions of mature alveolar process

A
  1. supportive regions: outer cortical (compact bone) plate and cancellous (spongy central portion)
  2. alveolar bone proper (alveolus): tooth socket - comprised of compact bone that anchors tooth
133
Q

three regions associated with alveolar bone proper

A
  1. interdental septum
  2. interradicular septum
  3. alveolar crest
134
Q

area of mucoperiosteum

A

lamina propria attached directly to periosteum of bone

135
Q

alveolar bone proper appearance

A

alveolus/tooth socket anchoring tooth

136
Q

alveolar crest

A

part where alveolus and outer cortical plate of alveolar process meet

137
Q

outer cortical plate

A

where attached gingiva is anchored to the bone

138
Q

how to determine if section is in lower or upper third

A

lower: cells are present in cementum
upper: no cells in cementum

139
Q

9 steps of root formation

A
  1. HERS develops
  2. HERS induce odontoblast differentiation
  3. deposition of dentin in root
  4. HERS root sheath breaks down
  5. ECR remnant of HERS
  6. ECR and dentin induce differentiation of dental follicle
  7. cementoblast cells from dental follicle migrate b/w ECR and deposit primary acellular cementum on dentin matrix
  8. PDL fibers differentiate from dental follicle
  9. alveolar bone proper (tooth socket) differentiates from dental follicle
140
Q

ankylosis

A

fusion of root dentin/cementum to bone due to loss of PDL

141
Q

reciprocal signaling between what controls eruption

A

HERS/REE and dental follicle

142
Q

3 phases of eruptive movements

A
  1. pre-eruptive
  2. eruptive; pre-functional
  3. post eruptive
143
Q

when do pre-eruptive movements occur

A

from cap stage until crown completion

144
Q

purpose of pre-eruptive movements

A

accommodate growing tooth size and number, formation of bony crypts between primary and permanent, and jaw growth

145
Q

function of pre-eruptive movements

A

to position tooth in jaw for eruptive process and emergence

146
Q

what do pre-eruptive movements do

A

change tooth’s orientation and physical position within the jaw to allow for emergence

147
Q

position in jaw during pre-eruptive movements

A

submerged within bony crypt
all movements occur within jaw below oral mucosa

148
Q

eruptive, pre-functional movements

A
  1. intra-osseous
  2. supra-osseous
149
Q

purpose of pre-functional movements

A

moves tooth from bony crypt to emerge into oral cavity and into functional occlusion
- starts with root initiation

150
Q

direction of pre-functional movements

A

axial.occlusal direction

151
Q

post-eruptive movement, functional eruption timing

A

following eruption

152
Q

post-eruptive movement, functional eruption purpose

A

required to maintain occlusal contact position while jaw grows and compensates for occlusal wear/interproximal wear

153
Q

post-eruptive movement, functional eruption position in jaw

A

functional occlusion with contact -> continues life of tooth

154
Q

what are pre-eruptive movements

A

movements occur prior to eruption
- movements of deciduous and permanent teeth prior to root formation

155
Q

where do pre-eruptive movements occur

A

within bony crypts that surround growing tooth germ crown

156
Q

function of pre-eruptive movements

A
  • move teeth in position for functional eruption into oral cavity
  • to accommodate growth of: developing jaw-bone, crown, adjacent teeth, increase in tooth number
157
Q

Movements related to tooth eruption begin during crown formation and require adjustments relative to the formation of ___

A

bony crypt and neighboring tooth

158
Q

Crowding due to increase crown size and increased tooth number is alleviated by ___

A

jaw growth and requires tooth movement

159
Q

type of movements for primary teeth

A
  1. mesial/distal -> vertical position (due to lengthening of jaw and increase height)
  2. lingual position -> facial (due to increase in length and width of jaw)
  3. occlusal (Vertical) -> due to height increase of jaw
160
Q

why does the jaw increase in length during development

A

length: allows primary molars to move backward and anterior teeth to shift forward

161
Q

whey does the jaw increase in height during development

A

allows developing teeth to move axial (upward)

162
Q

why does the jaw increase in width during development

A

allows development teeth to move outward to accommodate the succedaneous teeth developing lingually

163
Q

pre-eruptive movement of anterior permanent teeth

A

teeth develop in same crypt
as primary erupts, bone is deposited between erupting primary crown and permanent
- permanent now sits lingual to apical 1/3 of primary. during eruption, will shift lingual to facial and begin root resorption

164
Q

pre-eruptive movement of posterior permanent teeth

A

physical displacement occurring as a result of jaw growth called BODILY MOVEMENT

PM: shift from lingual/occlusal position to interradicular position of primary molar
Molars: involves a rotational movement as jaw increases in length and height

165
Q

what is the angle at which permanent molars move pre-eruptively

A

maxillary molar crown - developing distal inclination shifts vertical

mandibular molar crown - developing mesial inclination rotates into vertical

166
Q

do both permanent premolars and molars develop interradicularly?

A

NO. PM does. Molars undergo bodily movement

167
Q

function of eruptive pre-functional tooth movements

A

to bring developing tooth into oral cavity and accommodate root elongation

168
Q

rate of movement between eruptive pre-functional tooth movements

A

intra-osseous: slow
supra-osseous: fast

169
Q

what must be done to facilitate eruptive, pre-functional movement?

A
  1. establish eruption pathway (remove overlying bone and remove overlying CT)
  2. fusion of REE to OE allowing for tooth to penetrate oral mucosa
  3. differentiation/remodeling of alveolar bone and PDL
170
Q

how does the removal of overlying bone and CT occur to allow tooth to move into oral cavity?

A

REE covering tooth crown signals dental follicle to activate osteoclasts and digestive enzymes

outcome
1. resorption of bone above crown occurs thru osteoclasts
2. enzymes degrade overlying CT
3. once CT of coronal dental follicle removed, REE begins to proliferate

171
Q

events during intra-osseous stage for primary tooth

A
  1. creation of eruption pathway
  2. root elongation continues as tooth moves axially
172
Q

Is a root required for eruption

A

NO

a rootless tooth can erupt as long as DF is present and functional

173
Q

events during supra-osseous stage

A
  1. clinical eruption (1/2 to 2/3 root formed)
  2. active eruption (2/3 to 3/4 root formed)
174
Q

what occurs during clinical eruption

A

1/2-2/3 root formed
- fusion of OE and REE
- tip of crown breaks thru fused epithelium

175
Q

what occurs during active eruption

A

2/3 to 3/4 root formed
- continued occlusal movement results in exposure of clinical crown
- active eruption continues until tooth enters occlusion

176
Q

mechanism of action for clinical eruption

A

penetration of crown thru oral mucosa due to occlusal/axial movement and thinning of epithelial/CT barrier

177
Q

outcomes of clinical eruption

A
  1. tip of crown breaks thru fused epithelium
  2. eruption establishes DGJ
  3. REE surrounds crown like a cuff and becomes junctional epithelium
178
Q

mechanism of action for active eruption

A
  • HERS signals to dental follicle to deposit and remove bone apically as needed to accommodate root elongation (root continues to grow during active eruption)
  • increased deposition/bone formation at alveolar crest (and inter-radicular septum for multirooted tooth) to maintain tooth position
179
Q

outcomes of active eruption

A
  1. exposure of clinical crown
  2. continued eruption of tooth thru mucosa results in position of DJG to shift apically relative to tooth
180
Q

passive eruption

A

continued exposure of anatomical crown due to an apical shift of gingiva and junctional epithelium (no tooth movement)

181
Q

gingival recession

A

due to periodontal disease/inflammation will expose more cementum as JE moves below CEJ due to loss of attachment epithelium

182
Q

clinical crown

A

exposed crown extending from cusp tip to area of gingival attacchment

183
Q

anatomical crown

A

entire crown, extending from cusp tip to CEJ

184
Q

DGJ

A

point where free gingival margin, sulcular epithelium, and JE meet

185
Q

what must be present for eruption to occur

A

dental follicle
removing DF removes signalling and cannot know to erupt

186
Q

what happens if DF is removed in coronal region

A
  • no bone resorption
  • no eruption
187
Q

what happens if DF is removed in apical region

A
  • no bone deposition
  • no eruption
188
Q

jaw growth and bone remodeling results in

A

pre-eruptive movements

189
Q

signaling from REE/HERS and DF (coronal bone resorption) results in

A

pre-functional intra-osseous

190
Q

root elongation and bone remodeling results in

A

pre-functional supra-osseous

191
Q

gingival resorption (e.g. removal of intervening CT of dental follicle) results in

A

clinical eruption

192
Q

late root formation and bone remodeling results in

A

active eruption

193
Q

bone and PDL remodeling, deposition of cementum, and mesial drift result in

A

post-occlusion

194
Q

major difference between permanent and primary tooth eruption

A

permanent tooth eruption requires exfoliation of primary tooth

195
Q

eruption pathway for anterior teeth

A

forms gubernacular canal (eruption canal) lingual to primary

196
Q

gubernacular canal contents

A

canal is a remnant remnant of successional dental lamina - aka gubernacular cord

gubernacular cord directs path of eruption for permanent anterior teetth

197
Q

eruption pathway for premolars

A

positioned between roots following pre-eruptive movement and being inter-radicular resorption between roots of primary molars

198
Q

eruption pathway for molars

A

must create a new eruption canal following pre-eruptive bodily movement since there is no primary tooth

199
Q

how are anterior primary teeth exfoliated for permanent anteriors

A

start resorption lingual to apical 1/3 of primary root -> moves facial/labial to erupts

200
Q

how are primary teeth molars exfoliated for PM

A

begins interradicular between roots primary molar, and PM graduallt moves occlusally

201
Q

is there primary tooth resorption to make room for permanent molars

A

No. Remodeling crypt to allow for mesial or distal rotation of tooth germ to vertical position to create eruption path

202
Q

pre-eruptive movement of primary teeth

A

movement due to jaw and increased tooth number

203
Q

eruptive action of primary teeth

A
  • coronal removal of overlying bone and CT by osteoclast/enzymes to establish eruption path
  • bone deposition/root elongation apically
204
Q

pre-eruptive movement of anterior permanent teeth

A

separate bony crypt formed, lingual to primary tooth

205
Q

pre-eruptive movement of PM permanent teeth

A

facial shift to interradicular position between primary molars
*pre-eruptive bodily

206
Q

pre-eruptive movement of molar permanent teeth

A

shifts crown position due to jaw growth
- maxillary distal incline to vertical
- mandibular distal incline to vertical
*pre-eruptive bodily movement

207
Q

eruptive, intra-osseous movement of anterior permanent teeth

A

remove overlying bone/CT
- forms gubernacular canal: eruption pathway for anterior teeth
- permanent moves lingual to facial in jaw, resorbing primary anterior root

  • root resorption of primary tooth
  • bone deposition/root elongation apically of secondary
208
Q

eruptive, intra-osseous movement of PM permanent teeth

A

inter-radicular root resorption of primary molars

209
Q

eruptive, intra-osseous movement of molar permanent teeth

A

removal of overlying bone and CT
- no resorption of primary tooth
- intra-osseous path similar to primary teeth

210
Q

histological features of exfoliation

A
  1. coronal resorption of alveolar bone crypt
  2. resorption of cementum of primary tooth and repair is possible of cementum
  3. resorption of dentin of primary tooth (osteoclasts/odontoclasts)
  4. localized necrosis of radicular pulp (and coronal pulp intact)
  5. loss of PDL fibers of primary tooth
  6. remodeling of PDL of permanent tooth
211
Q

root resorption and repair

A

shown by reversal line
- signs of repair in secondary cementum and PDL reanchorage

212
Q

mechanisms controlling exfoliation

A

extrinsic signals originating from permanent tooth and intrinsic signals from primary tooth

213
Q

extrinsic signaling during exfoliation

A

between REE and dental follicle

facilitates breakdown of overlying gingival CT and bone and dental hard tissue of primary tooth by producing enzymes and recruiting osteoclasts/odontoclasts to the area

214
Q

intrinsic signaling during exfoliation

A

comes from the pulp, cementum, and PDL of the primary tooth

serve in recruitment of odontoclasts/osteoclasts to begin root resorption

215
Q

when do all crowns of primary teeth start to calcify? when are all crowns complete?

A

start to calcify prior to birth (5 mo. in utero)
crowns complete by 1 year

216
Q

6/4 rule

A

from birth, 4 teeth erupt for each 6 mo. of age
typically 2/3 of root formed at clinical eruption

217
Q

Eruption begins with the primary Mandibular central incisors around __ mo.

A

Eruption begins with the primary mandibular central incisors around 6mo.

218
Q

Eruption sequence for primary teeth:

A

CI, LI, M1, C, M2

219
Q

Primary M1 erupts @ __ and M2 erupts @ __

A

1 yr; 2 yrs

220
Q

primary teeth root isn’t complete until __ post-eruption

A

1-1.5 years

221
Q

what is one of the last permanent teeth to erupt due to having longest eruption path

A

maxillary canine

222
Q

when do permanent first molars begin crown formation

A

at birth

223
Q

what are the first permanent teeth to erupt

A

first mandibular molars followed by maxillary molar at 6 years

224
Q

what are the first teeth to erupt that develop from successional lamina

A

mandibular central incisors - erupts at 6 years (all about the same time as first molars)

225
Q

eruption sequence of permanent teeth

A

M1, CI, LI, canines, PM1, PM2, M2, M3

mandibular arch ahead of maxillary arch

226
Q

how old when permanent canines and PM erupt? when do the second permanent molars erupt?

A

canines and PM: 9-11
second permanent molars: 12 yrs

227
Q

do permanent teeth follow the rule of 4’s?

A

yes, except for 3rd molars

228
Q

what is premature exfoliation? causes?

A

exfoliation prior to normal age

causes: dental caries, defective root formation (short roots), defective tooth anchorage (hypoplasia cementum or dentin dysplasia), trauma, infection/inflammation, or systemic disease

229
Q

what is delayed exfoliation? causes?

A

retention of primary tooth (occurs beyond normal exfoliation time)

causes: hypodontia (congenital absence) of successor, primary tooth in submerged position due to ankylosis of primary tooth with bone, abnormal position of permanent tooth leads to ectopic eruption, impaction of successor’s teeth, or delayed eruption of successor

230
Q

enamel organ germ layer

A

ectoderm

231
Q

dental papilla germ layer

A

ectomesenchyme

232
Q

dental follicle germ layer

A

ectomesenchyme

233
Q

when primary tooth at bell stage, successional tooth at _ stage

A

bud

234
Q

primary anterior tooth at crown stage, successional tooth at _ stage

A

cap

235
Q

primary anterior tooth at early root stage, successional tooth at _

A

late bell

236
Q

primary tooth at functional stage, successional tooth at

A

early to mid crown

237
Q

primary anterior tooth shedding, successional tooth at

A

early root

238
Q

if there is an absence of a primary second molar, what corresponding permanent tooth is missing? why?

A

permanent second pre molar would be missing. permanent 2nd PM develops from successional lamina of primary tooth predecessor

239
Q

when does initiation, bud, cap, early bell, late bell, crown and root stage occur in primary teeth?

A

initiation: 6-8 weeks prenatal
bud: 8-10 weeks
cap: 10-12 week
early bell: 12-14 weeks
late bell: 14-18 weeks

crown stage: 18 weeks prenatal (all crowns begins to calcify by 6 months in utero and complete before 1 year post natal

root stage: roots complete 1-1.5 years post eruption, all complete by 3 years

240
Q

when does initiation, bud, cap, early bell, late bell, crown and root stage occur in permanent teeth?

A

initiation -> late bell: 4 months prenatal 1st molar, 5 months incisor, and all other begin post natal starting 10 months

crown stage: 1st M calcify at birth, CI 4 months post natal, all other by 4 years. all crowns complete by 8 years and 3rd molar is last to calcify at 8-10 years

root: root complete 3 years post-eruption. all complete by 16 years EXCEPT 3rd which occurs at 25 years

CUSOD Oral Histology (1 decks)

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