Oucod Oral Histology Exam 1 Written

Front 1

During development, what cells thicken in the location of the maxillary and mandibular embryonic dental arches?

Back 1

Epithelium

Front 2

Epithelium signals ______ cells to induce downward growth of epithelium at each location of future tooth.

Back 2

neural crest cells

Front 3

Neural crest cells initiate tooth formation by inducing downward growth of overlying ____ ____.

Back 3

oral epithelium

Front 4

During which weeks of development does neural crest cells induce downward growth of oral epithelium?

Back 4

Begins at 5 or 6 weeks of fetal life

Front 5

What 2 structures form during morphogenic bud stage of tooth formation.

Back 5

dental and vestibular lamina

Front 6

Name the 3 main morphological stages of tooth formation.

Back 6

bud, cap, bell

Front 7

During the bud stage, which cells of tooth bud are continuous with the basal cells of the oral epithelium and will differentiate into the inner and outer enamel epithelium of the enamel organ.

Back 7

basal cells

Front 8

Name the major components of the cap stage.

Back 8

enamel organ, dental papilla, dental sac

Front 9

What are the 4 layers of the enamel organ?

Back 9

Outer and inner dental epithelium, stratum intermedium, stellate reticulum

Front 10

At end of cap stage dental lamina becomes ____

Back 10

perforated

Front 11

The 3 major component of the bell stage are?

Back 11

enamel organ, dental papilla, dental sac

Front 12

Dental lamina begins to disintegrate during which stage?

Back 12

bell stage

Front 13

Joining of inner and outer enamel epithelium.

Back 13

Cervical loop

Front 14

Name the stage during which: Dentin and enamel begin to be deposited. Capillaries surround enamel organ to supply nourishment to the ameloblasts. Oxygen and nutrients are delivered by the cells of the stratum intermedium.

Back 14

Appositional stage

Front 15

Name the layers of the appositional stage (top to bottom)

Back 15

Ameloblasts
Enamel
Dentin
Odontoblasts

Front 16

What structure forms dentin and the dental pulp?

Back 16

dental papilla

Front 17

What structure forms cementum, PDL, and alveolar bone?

Back 17

dental sac

Front 18

Successional tooth dental lamina usually forms on which side of primary tooth buds?

Back 18

lingual side

Front 19

Serre's pearls are left over from what structure?

Back 19

dental lamina

Front 20

Congenital absence of teeth is a consequence of:

Back 20

1)Physical obstruction or disruption of the dental lamina. 2)Space limitation. 3)Functional abnormalities of the dental epithelium. 4)Failure of initiation of the underlying mesenchyme.

Front 21

Abnormal: absence of six or fewer permanent teeth .

Back 21

hypodontia

Front 22

Abnormal: absence of more than six permanent teeth

Back 22

oligodontia

Front 23

What's likely responsible for oligontia?

Back 23

gene mutation

Front 24

Name the steps of Cytodifferentiation (cytogenesis).

Back 24

1. preameloblasts differentiate
2. odontoblasts differentiate
3. odontoblasts secrete dentin
4. ameloblasts secrete enamel

Front 25

Name the 5 functional stages of cytodifferention.

Back 25

morphogenic, organizing, formative, maturative, protective,

Front 26

Odontoblasts produce predentin. Which is what kind of tissue?

Back 26

connective tissue resembles bone (collagen fibers in a proteoglycan/glycoprotein-rich ground substance)

Front 27

Ameloblasts produce unique epithelial product. What are they?

Back 27

two glycoproteins: amelogenins and enamelins

Front 28

dentin undergoes calcification (hydroxyapatite) after deposition, whereas ____ contains some hydroxyapatite at deposition.

Back 28

enamel

Front 29

Amelogenins removed by?

Back 29

ameloblasts

Front 30

When are ameloblasts lost?

Back 30

ameloblasts are lost when tooth erupts.

Front 31

Ameloblast and odontoblasts are similiar in that: product formation begin at?

Back 31

DEJ at cusp or incisal edges of tooth

Front 32

Root formation begins when?

Back 32

Crown formation is complete; developing tooth has started its eruptive movement; down-growth of epithelial root sheath (ERS) and diaphragm; ERS induces odontoblast formation

Front 33

A reflection of IEE to OEE, encloses pulp cavity, opening becomes apical foramen.

Back 33

Epithelial diaphragm

Front 34

Grows apically, shapes root and induces odontoblasts to deposit dentin, shapes dentino-cementum (D-C) junction.

Back 34

Epithelial root sheath

Front 35

Epithelial root sheath grows apically at same rate of eruption. What kind of growth?

Back 35

Radicular growth

Front 36

Basement membrane on both sides of epithelial root sheath breaks down. Epithelial root sheath disintegrates and forms?

Back 36

epithelial rests or Islands of Malassez

Front 37

___ move to root and differentiate into cementoblasts.

Back 37

Fibroblasts

Front 38

Calcification of what is required for cementum formation.

Back 38

predentin

Front 39

Cementum laid down as:

Back 39

cementoid

Front 40

Acellular cementum is deposited first, secretion of cementum traps what fibers?

Back 40

fibers of PDL

Front 41

Little cementum is deposited during tooth eruption, much cementum deposited after ___.

Back 41

occlusion

Front 42

Trapped in cellular cementum

Back 42

cementocytes

Front 43

Remnants of ERS (epithelial rests) become embedded in:

Back 43

PDL

Front 44

Nerves, arterioles and venules enter through apical foramen. At completion of root formation, what determines foramen diameter

Back 44

epithelial diaphragm

Front 45

Multirooted teeth are formed by: horizontal (inward) growth of subsequent ___ ____ to fuse centrally

Back 45

epithelial diaphragm

Front 46

Same process of dentin and cementum deposition occurs in multirooted teeth on the inner, ___ , surface of the roots

Back 46

interradicular

Front 47

How are primary teeth anchored?

Back 47

Primary teeth are anchored in a single bony trough

Front 48

Secondary teeth are anchored in individual bony sockets, separated by?

Back 48

interdental bone

Front 49

Hydroxyapatite (HA) accounts for what percent of total weight of enamel?

Back 49

96%

Front 50

Enamel rods extends from?

Back 50

DEJ to outer surface of tooth

Front 51

Organic component of enamel is 90-95% protein, what are they?

Back 51

enamelin and amelogenin

Front 52

1/2 length of rod near DEJ is ___; near tooth surface is straight

Back 52

wavy

Front 53

Are there more enamel rods near the DEJ or near the surface?

Back 53

More at DEJ

Front 54

Rhythmic deposition of enamel in 4um bands results in what? Corresponds to a daily enamel deposition.

Back 54

cross striations

Front 55

Cross section of enamel rods has what shape?

Back 55

key-hole shape

Front 56

“head" is usually directed toward which surface

Back 56

occlusal(cuspal/incisal) surface

Front 57

Ameloblast's hexagonal shape is a result of the shape of?

Back 57

Tome’s process

Front 58

The head of enamel rod is formed by?

Back 58

a single ameloblast

Front 59

The tail region produced by up to how many ameloblasts?

Back 59

3 neighboring

Front 60

What are released from concave surface of Tomes' process.

Back 60

Amelogenins and enamelins

Front 61

Maturation of enamel involves removal of ____ allowing crystallites to increase in thickness and width but not in length or number.

Back 61

amelogenins

Front 62

Lack of Tome’s process =

Back 62

prismless enamel

Front 63

Prismless enamel occurs at?

Back 63

DEJ and at surface of enamel

Front 64

Junction of rod head with an adjacent rod tail represents:

Back 64

an interrod space - space between rod heads

Front 65

Interrod space is filled with:

Back 65

HA crystals with different orientations, organic matrix and water

Front 66

Greater amount of matrix at convex border at top of enamel rod =

Back 66

enamel rod sheath

Front 67

Distinction between rod head and sheath based on:

Back 67

enamel matrix and degree of calcification

Front 68

In rod head HA crystals occupy nearly all space, with little matrix components (increases strength); whereas rod sheath is almost exclusively:

Back 68

enamel matrix with little or no HA present (decreasing its density/strength).

Front 69

HA crystal is composed of 3 zones:

Back 69

hydration shell
crystal surface
crystal interior

Front 70

Superficial ions of crystal interior are:

Back 70

hydrated

Front 71

Ions like Na+, Mg++, Sr++, Ra++, C03, citrate and F may interact with HA affecting what?

Back 71

hardness of enamel (i.e. fluoride)

Front 72

In the tail of enamel rods, HA crystals are oriented how?

Back 72

obliquely

Front 73

Ca10(PO4)6(OH)2

Back 73

HA

Front 74

Which ion causes decrease in enamel crystal solubility in acidic conditions?

Back 74

fluoride ion (F)

Front 75

Groups of enamel rods curve up and out while other groups curve down and into tooth. Bending of rod groups into neighboring zones gives appearance of light and dark bands perpendicular to surface.

Back 75

Hunter-Schreger bands

Front 76

Hunter-Schreger bands are visible only if tooth is sectioned along which axis?

Back 76

longitudinal axis

Front 77

Extend through entire width of enamel layer from incisal or cuspal area to cervical region, result of improperly mineralized enamel.

Back 77

enamel lamellae

Front 78

Name 3 ways for enamel Lamellae formation.

Back 78

Uncalcified enamel matrix, debris of enamel organ, debris from oral cavity

Front 79

Normal features in enamel
characteristically-shaped defects in calcification
inner 1/3 of enamel layer region where enamel rods are curved; so numerous enamel near DEJ region has organic content 3X normal; represent non-calcified parts of enamel rods and widened rod sheaths

Back 79

enamel tufts

Front 80

Odontoblast processes cross DEJ, not withdrawn rapidly enough from contact with preameloblasts and become trapped in initial layers of enamel at DEJ

Back 80

enamel spindles

Front 81

Cross striations extend at right angles to enamel rods, light and dark alternate banding gives approximately 4um apart on rods daily growth increment. This is comparable to what in dentin?

Back 81

lines of von Ebner of dentin

Front 82

Contain more organic matrix than adjacent lighter areas; reflect stress (disease, birth) during formation of enamel layer; irregularity in calcification due to retraction of Tome’s process
dark appearance reflects their reduced level of calcification;

Back 82

Stria of Retzius

Front 83

At birth, the stria of retzius is also called what?

Back 83

neonatal line

Front 84

Surface manifestation of stria of Retzius; grooves and interspersed ridges near cervix of tooth which eventually wear down.

Back 84

Perikymata

Front 85

Twisted groups of enamel rods in cuspal region of tooth; may extend out through entire enamel layer; gives strength to this region.

Back 85

Gnarled enamel

Front 86

Pits and fissures in premolars and molars are result of?

Back 86

Ameloblasts moving to smaller surface, have problems of crowding

Front 87

T/F: Fracture likelihood is decreased when walls of prep do not parallel long axis of enamel rods.

Back 87

True

Front 88

T/F: Margins of restorations should be placed in gnarled enamel.

Back 88

False. Non-gnarled: impossible to avoid undermining enamel prisms in gnarled enamel

Front 89

Condition: enamel crystals dissolve in central regions (or core) along entire long axis; doughnut-shaped morphology.

Back 89

precarious enamel lesions

Front 90

Condition: exhibits a pronounced shortening of the crystal in length, followed by enamel breakdown and gross cavitation.

Back 90

carious enamel lesions

Front 91

Acid etching roughens the enamel surface by eroding what?

Back 91

preferentially rod head and more easily rod sheath

Front 92

Etching will not roughen enamel surfaces in regions of:

Back 92

prismless enamel (especially primary teeth)

Front 93

Dentin is comparable to bone and has what composition?

Back 93

cells (odontoblasts); fibrous matrix (type I collagen fibers); ground substance (proteoglycan and glycoproteins)

Front 94

Predominant organic component of dentin is fibrous matrix composed of:

Back 94

92% collagen

Front 95

Prior to dentinogenesis cells of IEE elongate and organize, causes differentiation of peripheral cells of dental papilla into:

Back 95

odontoblasts

Front 96

What comprise the first dentin formed or mantle dentin?

Back 96

Large collagen fibers (von Korff fibers found in pulp) and ground substance

Front 97

What secrete collagen and increase in size, obliterate any extracellular matrix between them.

Back 97

odontoblasts

Front 98

What is formed between adjacent odontoblasts.

Back 98

junctional complexes

Front 99

Odontoblastic process becomes surrounded by dentin matrix; mineralized tunnel containing odontoblast process are called:

Back 99

dentinal tubule

Front 100

Circumpulpal dentin is denser (harder) than:

Back 100

mantle dentin

Front 101

The production of an organic matrix (predentin) that is mineralized (calcified) through deposition of HA crystals.

Back 101

dentinogenesis

Front 102

Dentin appears radially striated due to presence of dentinal tubules; tubules span pulp cavity to DEJ; odontoblastic process extends into:

Back 102

S-shaped tubule

Front 103

Small waves in tubules
crests are 4 um apart, reflect minor changes in direction of odontoblast movement during successive 24 hour periods.

Back 103

Secondary Curves

Front 104

Tubular density is actually 4X higher in the dentin near:

Back 104

the pulp

Front 105

Dentinal tubules of crown dentin are relatively unbranched; whereas root dentinal tubules display numerous side branches or:

Back 105

canaliculi

Front 106

Coarser bundles of collagen,less heavily calcified, collagen fibers extend perpendicular to the dentinal tubules)

Back 106

Intertubular dentin

Front 107

Forms 1 um thick layer within tubule, exhibits a delicate collagenous matrix, is heavily calcified

Back 107

Peritubular dentin

Front 108

During dentin deposition, the cell body of the odontoblast secretes ___ dentin,

Back 108

intertubular

Front 109

What dentin calcifies as soon as it is deposited.

Back 109

peritubular

Front 110

Very large collagen fibers lying perpendicular to the DEJ in the mantle layer

Back 110

Von Korf’s fibers

Front 111

Islands of uncalcified dentin in crown located along line between mantle and circumpulpal dentin, represent imperfections in the calcification front, lack of fusion between spherical globs of calcifying dentin

Back 111

Interglobular dentin

Front 112

Name the dentin layers from enamel to pulp:

Back 112

mantle, globular, circumpupal

Front 113

HA is deposited as spherical aggregations of crystals; spherical aggregations grow in size and finally fuse

Back 113

Mineralization front

Front 114

Peripheral dentin of root; uncalcified islands of dentin; appear as dark grains adjacent to the dentino-cementum (D-C) junction similar to interglobular dentin but much smaller

Back 114

Granular Layer of Tome’s

Front 115

Daily growth rhythm regular bands in dentin, average daily deposition = 4 um lighter region (better calcified) and darker (less calcified). Compare to cross striation in enamel.

Back 115

Lines of von Ebner

Front 116

Comparable to Stria of Retzius in enamel; caused by illness or major changes in body metabolism; dark band of less calcified dentin, less common than imbrication lines follow contour of what used to be pulpal surface

Back 116

Contour lines of Owen

Front 117

Name 3 theories of teeth sensory stimulation:

Back 117

Intratubular nerve, transduction (odontoblast), hydrodynamic

Front 118

What type of dentin is formed after the completion of the apical foramen?

Back 118

2nd dentin

Front 119

Dentin formed in response to irritant.

Back 119

reactive dentin

Front 120

Empty dentin tubules fill with air appear as dark band on ground sections.

Back 120

dead tracts

Front 121

Dead tracts filled in with mineral, appears transparent

Back 121

Blind tracts or sclerotic dentin

Front 122

Consists of cells, Types I and III collagen fibers and ground substance. Arise from dental papilla. Support odontoblast.

Back 122

pulp cavity

Front 123

Cell free layer of pulp cavity with von Korff's fibers, fibers pass from pulp into matrix of dentin layer, numerous capillaries and nerves are found here

Back 123

Zone of Weil

Front 124

Predominant cell type of pulp

Back 124

fibroblast

Front 125

Name the nerve plexus in the pulp periphery?

Back 125

Parietal nerve plexus of Raschkow

Front 126

Name the layers of the pulp periphery from dentin:

Back 126

Odontoblasts, zone of weil, cell rich layer, parietal never plexus

Front 127

Name the 2 types of nerve fibers in pulp:

Back 127

Sympathetic ANS and afferent sensory fibers of Trigemeninal (5)

Front 128

Sharp pain in carried in what type of nerve fiber? Dull?

Back 128

sharp = myelinated; dull = unmyelinated

Front 129

Name the regions of pulp:

Back 129

coronal pulp, pulp horn, radicular pulp

Front 130

With age, what happens to the pulp composition?

Back 130

Pulp becomes less cellular, more fibrous, reduced in size due to further dentin deposition.

Front 131

Calcified bodies in pulp composed of dentin, contain tubules dentin, usually formed by epithelio-mesenchymal interaction. Radial.

Back 131

True pulp stone (denticle)

Front 132

Irregularly calcified structure, displays concentric rings of calcification, formed by calcification of debris

Back 132

False Pulp Stones

Front 133

Deposited after epithelial root sheath (ERS) breakdown
dental sac cells (fibroblasts) contact surface of root dentin.

Back 133

cementum

Front 134

About how much of the root has been formed at first cementum deposition.

Back 134

2/3 of root

Front 135

On cervical 1/2 of root cementoblasts reside on surface, width does not increase markedly during functional life of tooth

Back 135

acellular cementum

Front 136

On apical 1/2 of root cementoblasts trapped (cementocytes), formed after functional occlusion

Back 136

cellular cementum

Front 137

What is the only source of nutrition for cementocytes.

Back 137

PDL

Front 138

Occurs when cementoblast layer pauses, is highly calcified layer of cementum
smooth in appearance

Back 138

Arrest lines

Front 139

Lines less common than in bone, cementum predominantly grows appositionally, does not undergo significant remodeling, observed from resorption activity of cementoclast, scalloped.

Back 139

reversal lines

Front 140

Reversal lines are resistant to?

Back 140

resorption

Front 141

Abnormal calcified bodies found within PDL, appear to form on cellular debris such as ERS remnants (epithelial rests/cell rests of Malassez), resemble pulp stones

Back 141

cementicles

Front 142

Cementicles are found in the PDL, a stone on the root of the teeth is probably?

Back 142

enamel pearl

Front 143

What percent of CEJ overlap, meet, and gap?

Back 143

Overlap 60%
Meet 30%
Gap 10%

Front 144

Forms sockets in which tooth root is suspended

Back 144

alveolar bone

Front 145

Continuous with bone of jaw =

Back 145

basal bone

Front 146

What happens to bone following tooth extraction.

Back 146

alveolar bone of edentulous patient gradually resorbed until only basal bone remains

Front 147

Name the layers of alveolar bone:

Back 147

cribriform plate, cortical plate, spongy bone

Front 148

Cortical plates are comprised of what type of bone:

Back 148

compact, lamellar bone

Front 149

A slight horizontal movement towards front of oral cavity. all tooth movement within socket results in bone remodeling.

Back 149

mesial drift

Front 150

Pressure on bone leads to osteoclast resorption in:

Back 150

(Howship's) lacunae

Front 151

In bone remodeling, what bone is first broken down?

Back 151

bundle bone

Front 152

Pulling on bone leads to:

Back 152

bone deposition to fill intervening space

Front 153

New bone is bundle bone and older bundle bone becomes rapidly remodeled into:

Back 153

lamellar bone with osteons