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Oral Biology > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

Where would you find odontoblasts in a fully matured tooth?

A

Between the pulp and dentin. Odontoblasts extend through dentin (dentinal tubules) Thus dentin is also considered a cellular tissue

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2
Q

Describe the composition of dentin.
Inorganic material
Organic material
Water

A

Inorganic material: 70%

Organic material: 20%

Water 10%

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3
Q

What makes up the inorganic material of dentin?

A

Hydroxyapatite

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4
Q

Why is it that demineralized dentin looks ‘stringy’?

A

A good portion of dentin is collagen (note it is a triple helical structure) and doesn’t demineralize. So when you demineralization the tooth, you are left with collagen

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5
Q

Describe what the HA crystals look like in dentin

A

HA crystals are flattened in rectangular plates along collagen

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6
Q

What is the knoop number of dentin, enamel, and bone? What does this mean?

A

Knoop number compares the relative hardness of one material to another

Bone: 50
Dentin: 68
Enamel: 343

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7
Q

What portion of the 20% organic portion of dentin is composed of collagen? What is the rest composed of?

A

90% collagen (fibrillar)

10% noncollagenous proteins (aid in the growing of HA crystals) (also note that this means that the noncollagenous proteins make up 2% of total dentin composition)

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8
Q

The collagen in dentin is mostly type ___, some ___ and ___

A

1 (similar to bone)

3

5

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9
Q

Name five non collagenous organic components found in dentin that is common with bone

A 
(BSP) Bone sialoprotein
(OP) osteopontin
(OC) osteocalcin 
(ON) osteonectin 
Matrix extracellular phosphoglycoprotein
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10
Q

Name 2 dentin organic components that can be found in bone but are mostly specific to dentin

A

DMP-1 : dentin matrix protein 1

DSPP - dentin sialophosphoprotein

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11
Q

DSPP (dentin sialophosphoprotein) found in dentin is further cleaved into what three proteins?

A

DSP - dentin sialoprotein

DPP - dentin phosphoprotein

DGP - dentin glycoprotein

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12
Q

DSPP is cleaved by ___ to form ___, ___, and ___

A

BMP-1

DSP

DGP

DPP

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13
Q

What is DSP (dentin sialoprotein)?

A

Proteoglycan

Prevents mineralization in dentin tubules*

Similar to DMP -1

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14
Q

What is DGP?

A

Dentin glycoprotein

Role unknown, but may be involved in biomineralization by causing nucleation of HA crystals

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15
Q

What is DPP?

A

Dentin phosphoprotein

Initiates HA formation (binds lots of HA)*

Attached to collagen

Not glycosylated

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16
Q

Defects in DSPP can cause ___

A

Dentinogenesis imperfecta types 2 and 3

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17
Q

Describe the three different types of deninogenesis imperfecta

A

Type 1: results form OI (defect in collagen 1), pulp chambers filled with abnormal dentin (OI = osteogenesis imperfecta - bones are messed up too)

Type 2: not associated with OI (strictly DSPP defect), pulp chambers filled with abnormal dentin

Type 3: enlarged pulp chambers, hypo-mineralization, possibly failure of DSPP expression (results in “floating crown”)

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18
Q

Odontoblasts have ____ origin

A

Mesenchymal

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19
Q

The dentin-pulp complex arises from the ____. The initial differentiation of odontoblasts is a critical interaction with the _______

A

Dental papilla

Inner enamel epithelium

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20
Q

Which is active first, coronal or apical odontoblasts?

A

Coronal odontoblasts are activated before apical odontoblasts

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21
Q

The DEJ has a ‘beautiful’ scalloped edge. What is the importance of the scalloping?

A

It prevents shearing forces from displacing the tissues. Provides a tighter seal between enamel and dentin

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22
Q

What provides the attachement of dentin to enamel in the DEJ?

A

Mineral components are intermingled

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23
Q

The first layer of dentin is called ____ and is closest to the DEJ.

A

Mantle dentin

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24
Q

What are Von Korff’s fibers? What are they secreted by?

A

Giant collagen 3 fibrils. Associated with fibronectin.

They span the entire width of mantle dentin and reach the IEE.

They are secreted by preodontoblasts

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25
Q

Describe the early formation of dentin

A

Developing odontoblasts extend Tome’s fibers into developing matrix and secrete dentin matrix components in matrix vesicles

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26
Q

Penetration of dentin fibers into the IEE are called ____

A

Enamel spindles. Note that these will contain collagen. Enamel doesn’t contain collagen, but pieces of collagen may extend form the dentin into the enamel

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27
Q

Early dentin (predentin) is ____ organic matrix

A

Non-mineralized

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28
Q

What are seed crystals? Describe dentin formation

A

Early odontoblasts will release seed crystals to form the non-tubular, mantle dentin. These will then burst to result in mineralization. (These are like balloons full of paint). As odontoblasts mature, they mineralize matrix directly via Tome’s fibers. (These are like paint rollers)

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29
Q

What is circumpulpal dentin?

A

All of the dentin that is not mantle dentin

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30
Q

Cell rests of malassez are derived from _____

A

HERS (hertwig’s root sheath)

Note that HERS also initiates odontoblast differentiation in the root

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31
Q

What are the differences between primary and secondary dentin?

A

Primary dentin: first dentin formed during development. Comprises the mantle dentin and the initial deposition of circumpulpal dentin

Secondary dentin: tubular dentin laid down subsequent to root formation. Secondary dentin is produced throughout life. It is continuous with primary dentin, yet histologically distinct

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32
Q

What is the difference between coronal and root dentin tubules?

A

Coronal dentin: tubules have a sigmoidal curve

Root dentin: tubules are much straighter

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33
Q

Secondary dentin deposition is greater around the ____ and ____ than ____

A

Roof and floor than the sides

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34
Q

What is tertiary dentin? Does it have tubules?

A

Dentin produced in response to insult. Acts to seal off dentinal tubules, or to form ‘bridges’ between dentin and restoration

Can have tubules, but often does not. Tubules are often disordered

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35
Q

Why is tertiary dentin also called osteodentin?

A

It resembles bone more closely than other types of dentin do

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36
Q

What is the difference between reactionary and reparative tertiary dentin?

A

Reactionary: trauma does not damage odontoblasts

Reparative: damage odontoblasts. Includes differentiation of mesenchymal cells, forming new odontoblasts.

Note that less DSP and DMP-1 , more BSP and OP

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37
Q

What are the three main macro structures of dentin?

A

Dentin tubules (with OD process)

Peritubular dentin (lines the tubules) (highly calcified)

Intertubular dentin (collagen 1 fibrils are arranged perpendicular to tubules)

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38
Q

What are dentinal tubules?

A

They run from DEJ to odontoblast layer

Fluid filled

Provide mechanical support to the enamel during loading.

Can form secondary branches, especially in the root

Note that after breaking through the DEJ, bacteria can quickly move through the tubules

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39
Q

What are dead tracts in regards to caries and dentin?

A

Trapped air in empty tubules - sealed off after odontoblasts death

Appear black in ground section

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40
Q

What is sclerotic dentin?

A

Collective term for tubules that have become occluded

Have a glassy, translucent appearance

Occurs naturally with age as peritubular dentin is deposited

Can occur by mineral deposition only. Diffuse mineralization around a living OD process, or mineralization of the cellular process and collagen fibers along the inside of the tubule

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41
Q

What is interglobular dentin?

A

Areas of hypomineralized dentin

Formed when fusion of mineral containing vesicles fails (thus common in or near the mantle dentin)

Can be associated with vitamin D deficiency or fluoride exposure during initial dentin formation

Tubules often run through areas of interglobular dentin: matrix is present

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42
Q

Dentin matrix is deposited continually at approximately ___ per day

A

4 microns

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43
Q

What are lines of von Ebner?

A

About every 5 days there is a dentinal layer deposited that has slightly different collagen orientation. Thus you can see this line around ever 20 microns

Note that secondary dentin is asymmetrically deposited, more slowly

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44
Q

What are contour lines of Owen?

A

Enhanced lines that indicate disruption of tooth formation

Equivalent to stria of retzius in enamel

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45
Q

What is the granular layer of Tomes?

A

“Funny looking dots” that are located around the roots of ground sections

Gets more granular toward the apical end.

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46
Q

What are three possible reasons for the formation of the granular layer of tomes?

A

Hypominrailzed areas of dentin, similar to interglobular dentin

Part of looped dentinal tubules found in the root sections, (artifact of sectioning)

Specialized dentin structures which form part of the dentin-cementum junction

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47
Q

What is the primary cell type of dental pulp?

A

Fibroblasts followed by odontoblasts

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48
Q

What are some components of the dental pulp?

A

Blood vessels
Nerves
Fibroblasts
Immune cells

Pool of progenitor cells for replacement and repair

These function to support structures for the mineralized components of the tooth

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49
Q

Name the four histological zones form outer to inner of the dental pulp

A

Odontoblast layer

Cell free zone of Weil

Cell rich zone

Pulp core

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50
Q

The soft CT matrix of the dental pulp is mostly comprised of collagen ____, but also some ____. There are also ____ and ____ which contribute to squidginess

A

3

1

Proteoglycans

Glycoproteins

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51
Q

What happens to dental pulp ECM as it ages?

A

Collagen content increases and fibrils aggregate into larger bundles, greatest concentration apically

Squidgyness decreases with age

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52
Q

What comprises the ground substance of the pulp?

A

Proteoglycans (GAG chains, glycoproteins, water

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53
Q

Name 5 proteoglycans found in pulp (dont stress about his too much, he says we dont really have to know it)

A

Chondroitin 6 sulfate

Chondroitin 4 sulfate

Heparin sulfate

Dermatan sulfate

Keratin sulfate

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54
Q

Odontoblasts are more ____ in shape in the crown, whereas they are more ____ in shape in the root.

A

Columnar

Cuboidal

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55
Q

How are odontoblasts held together? Why is this significant?

A

Junctional complexes

Adherens junctions

This is significant because it may give a degree of permeability to the OD layer

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56
Q

Odontoblasts can form _____ with pulpal fibroblasts

A

Gap junctions

This allows the fibroblasts in the pulp to respond to external conditions

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57
Q

True or false… odontoblasts only lay down collagen

A

False… they also lay down non-collagenous protein

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58
Q

Describe aged odontoblasts

A

Fewer organelles

Less secretory activity

Nucleus somewhat more central

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59
Q

How are odontoblasts regenerated?

A

Can be replaced from mesenchymal progenitor pool

Sequestered growth factors in dentin matrix

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60
Q

What is the predominant cell type found in the dentin-pulp complex? Where is it found?

A

Fibroblasts

Pulp core and cell rich zone

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61
Q

Where are macrophages and dendritic cells found in the tooth?

A

Macrophages present in dental pulp

Dendritic cells found under odontoblast layer

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62
Q

When will you find lymphocytes in the pulp?

A

Low numbers normally. Higher numbers in infected pulps

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63
Q

Pulp vasculature arises from the ____ arteries, which will ultimately branch into the ___ and ____ arteries

A

External carotid

Superior/inferior alveolar

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64
Q

There are about ___ - ___ arterioles per tooth that enter the apical foramen

A

4-8

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65
Q

Where are the capillaries networks found in the tooth? They are found in a different location during primary dentin formation, where are the found at this time?

A

Cell free zone

During primary dentin formation, they are found in the odontoblast layer

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66
Q

True or false… in the tooth the lymphatic drainage is equal to arterial interstitial flow

A

True

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67
Q

In the pulp, nerve fibers branch out through the coronal pulp forming the plexus of ____

A

Raschkow

Found especially under cusps

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68
Q

True or false… in root pulp there are no plexuses of Raschkow

A

True. There are only branches of nerve fibers

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69
Q

What are the nerve sources for the innervation of the pulp?

A

Afferent nerves coming from trigeminal

Sympathetic branches come from the superior cervical ganglion

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70
Q

Nerve bundles consist of both ___ and ___ axons

A

Myelinated alpha delta

Unmyelinated C

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71
Q

Myelination decreases as fibers proceed towards the ____

A

Coronal pulp

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72
Q

True or false… some unmyelinated nerve axons pass into the dentinal tubules

A

True

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73
Q

What are the three proposed models of dentin sensitivity? Describe the reasoning behind each model.

A

Direct innervation - there are nerves in some tubules (but a minority)

Odontoblast nociception - OD are neural crest derived, gap junctions exist with pulpal nerves (no direct synapse however)

Tubule fluid conductance - changes in fluid levels can cause sensitivity

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74
Q

Mineralized tissue can form inappropriately in the pulp (pulp stones). Describe the four types

A

Free

Surrounding by soft pulp tissue

Attached to dentin

Embedded in secondary dentin

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75
Q

Pulp stones are likely to occur around….

A

Collagen fibers

Dead cell aggregates

Thrombi

(More prevalent after 50 years of age)

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76
Q

What are some age related changes in pulp?

A

Recession of pulp due to secondary dentin formation

Reduction in cell response to stimuli

Decrease in permeability (more brittle teeth)

Loss of nerve axons, decrease in sensitivity

Dystrophic calcification in central pulp (not pulp stones, this is fossilized collagen fibrils)

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77
Q

Name and describe the five types of physiologic tooth movements

A

Preeruptive - positioning of tooth germs prior to eruption

Eruptive - the movement of the tooth into functional occlusion

Post eruptive - movements in compensation for the growth of the jaws. Meant to keep the tooth in occlusion

Shedding - the programmed loss of primary teeth

Avulsion - an extreme example of non-physiologic tooth movement (getting a tooth knocked out)

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78
Q

Preeruptive tooth movements take case in a ____ and thus are associated with bone ___ and/or ___

A

Boney crypt

Resorption

Deposition

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79
Q

What is the difference between bodily movement and directional/eccentric growth?

A

Bodily movement - increase in length

Directional/eccentric growth - increase in height

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80
Q

What occurs with the oral epithelium when primary teeth erupt?

A

As primary teeth erupt, fusion of the oral epithelium with the reduced enamel epithelium occurs, creating an epithelium lined channel through which the tooth emerges

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81
Q

What is the gubernacular canal? The gubernacular canal forms along the remnants of the ____ attached to the lamina propria

A

A channel that develops between the alveolar bone around the primary tooth and the permanent tooth as it erupts.

Dental lamina

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82
Q

How fast do permanent teeth move through bone? How fast do they move through the gubernacular canal?

A

Intraosseous: 1-10 um/day

Gubernacular canal: 75 um/day

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83
Q

What are the four theories of tooth eruption?

A

Bone remodeling theory

Root growth theory

Vascular pressure theory

Fusion hammock theory

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84
Q

Describe the bone remodeling theory. What are two problems in regards to this theory?

A

Bone deposits apically to the erupting tooth, propelling the tooth into the oral cavity.

Problems: removal of dental follicle - no bone remodeling and thus no eruption

Replica teeth placed in an intact follicle still form an eruption pathway

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85
Q

Describe the root growth theory. Name three problems in regards to this theory.

A

Root formation pushes the tooth outwards.

Problems: pushing against what?
Not enough root to account for the movement to occlusal plane. If you cut off the roots, the tooth will still erupt

86
Q

What is the vascular pressure theory? Name two problems in regards to this theory

A

Blood vessels at the tooth apex push it outwards due to hydrostatic pressure.

Pressure: no way is this pressure suffifcinet . When you remove the vascular supply, teeth still erupt

87
Q

What is the cushion hammock theory? What is a problem regarding this theory?

A

A magic ligament under the tooth pushes it out

Problem: “like eleven, pixies, and true happiness, this ligament most likely doesn’t exist”

88
Q

Currently, it is thought that the ____, developing after root formation, is the driving force for tooth eruption.

A

Periodontal ligament

89
Q

How does the PDL help the tooth erupt?

A

PDL fibroblasts pull against each other and colleges bundles, exerting pressure on the tooth.

Note that teeth can still erupt without a PDL, and the presence of a PDL doesn’t ensure eruption

90
Q

The ____ is critical for tooth eruption, as it initiates bone resorption and the breakdown of soft tissues allowing for eruption

A

Dental follicle

91
Q

What are the key mediators of eruption to cause tissue resorption in bone, connective tissue, and epithelium?

A

Colony stimulating factor-1

Interleukin 6

Interleukin 1a

Monocyte chemotactic protein-1

92
Q

What are the key mediators for eruption involved in tissue formation?

A

BMP - 2

BMP - 6

Runx2

TGF-beta

EGF

93
Q

What is the purpose of post eruptive tooth movement?

A

To accommodate the growing jaws

Compensate for occlusal wear

Compensate for interproximal wear

94
Q

In regards to orthodontic tooth movement, compression of bone will ___ bone whereas pulling on bone will ____ bone

A

Resorb

Deposit

95
Q

True or false… orthodontic tooth movement is NOT physiological and does involve some tissue damage and internal bone resorption, probably due to imperfect force distribution within the PDL

A

True

96
Q

What is hyalinization?

A

Damage to cells in the PDL, loss of cells = no remodeling

97
Q

The PDL functions to ____ whereas the deposition of new cementum/alveolar bone functions to ___

A

Keep the tooth in occlusion

Keep the tooth in its new adjusted position

98
Q

Post eruptively, teeth tend to move mesial or distal due to pressure?

A

Mesial

If you load the back teeth, they are going to push the anterior teeth together in a mesial fashion

99
Q

The hard tissues of the tooth (namely dentin/cementum) are resorbed by the action of ___

A

Odontoclasts

100
Q

True or false.. primary teeth will not shed without a succeeding permanent tooth.

A

False. Often, primary teeth will still shed (much later), without the presence of a permanent tooth underlying it.

Teeth will erupt probably due to the growth of the jaw and increase in masticatory forces

101
Q

What are the combination of factors that lead to shedding of primary teeth?

A

Pressure from erupting permanent tooth will lead to resorption of hard and soft tissues as well as decreased mechanical stability. Mechanical instability will lead to increased resorption of hard and soft tissues.

102
Q

Whose teeth typically erupt first, girls or boys?

A

Girls

103
Q

What is the order of eruption of secondary teeth from anterior to posterior teeth in the maxillary arch?

A

781-0062

104
Q

What is the order of eruption of secondary teeth from anterior to posterior teeth in the mandibular arch?

A

679-0161

105
Q

What are the three principle components of the periodontium?

A

Alveolar process

Cementum

Periodontal ligament

106
Q

The periodontium develops during a series of complex interactions of ___, ___, and ____

A

Mesenchyme

HERS

Dental follicle

107
Q

What is a gomphosis?

A

Fibrous peg-in-socket joint

108
Q

The alveolar process is formed by ___ ossification, beginning in the ____ week of uterine life

A

Intramembranous

109
Q

____ develop around tooth germs, such that they eventually form the sockets

A

Crypts

110
Q

The alveolar process develops substantially during ___

A

Tooth eruption, under the influence of the dental follicle

111
Q

What are anodontic individuals?

A

Alveolar process development is impaired

112
Q

What is the difference between alveolar bone proper and supporting alveolar bone?

A

Alveolar bone proper - compact bone only. Lines the tooth socket most directly. Consists of the cribriform plate and lamina dura

Supporting alveolar bone - both compact and trabecular bone. Consists of cortical plates (compact bone) and central spongiosa (trabecular bone component)

113
Q

What kind of canals run through the cribriform plate in the alveolar bone proper?

A

Volkmann’s canals. (Arterioles run through vokmann’s canals)

114
Q

What is the lamina dura?

A

Radiographic term for the area of PDL attachment

115
Q

What is bundle bone?

A

Histological term referring to sharpey’s fibers (collagen fibers of PDL) embedded in bone)

116
Q

Is the inner alveolar bone proper (towards PDL) primarily consisting of woven bone or lamellar bone?

A

Woven bone (more collagen 3) because it is more dynamic due to the constant adaptation of tooth. Lamellar bone is also present though

117
Q

True or false… The inner alveolar bone proper has a smooth surface in young individuals but becomes rougher with age as it is remodeled over and over again

A

True

118
Q

What is the alveolar crest?

A

Junction of cortical plate and alveolar bone proper

119
Q

Where is alveolar bone the thinnest and thickest?

A

Thinnest in maxilla

Thickest in premolar and molar region of mandible

120
Q

True or false the central spongiosa is more prevalent in the maxilla than the mandible

A

True

121
Q

True or false… the central spongiosa is more distinguished in the anterior portion of the jaws as opposed to the posterior portion

A

False. It is absent/diminished in the anterior region

122
Q

What is the difference between the interradicular septum and the interalveolar septum?

A

Interradicular septum - bony septum between roots of a single tooth

Interalveolar septum - bony septum between adjacent teeth

123
Q

What are the four functions of alveolar bone?

A

Protection and structure of the socket for the tooth to rest in

Attachment of Sharpey’s fibers of the PDL which are embedded in bone

Support of tooth roots, especially facial/lingual

Distribution of loading from the tooth and the PDL to the surrounding bone

124
Q

When does the PDL develop in reference to when cementum and the alveolar process develops?

A

At the same time

125
Q

The PDL develops after detachment of ___

A

HERS

126
Q

Fibroblasts produce and organize PDL collagen fibers, generally in an oblique orientation orientation. Where are these fibroblasts derived from?

A

Ectomesenchyme cells from the dental follicle

127
Q

True or false.. PDL fiber orientation changes with eruption. The fibers continue to remodel throughout life. Developing cells of the PDL may also prevent mineralization, preventing ankylosis

A

True

128
Q

What cells are associated with PDL?

A 
Fibroblasts
Mesenchymal cells
Epithelial cells
Macrophages
Osteoblasts 
Osteoclasts 
Cementoblasts
129
Q

The PDL ranges in width between ___ mm and ___ mm

A

.15mm and .38mm

130
Q

The width of the PDL ____ with age because…

A

Decreases

Because cementum increases in thickness, closing off the width. also perhaps masticatory forces decrease

131
Q

What type of collagen is present in the PDL?

A

1
3
7

132
Q

True or false… when the PDL undergoes remodeling, entire bundles are changed at a time.

A

False… individual fibers are remodeled whilst the overall bundle is not changed, making a very dynamic environment

133
Q

What is the main elastic fiber of the PDL

A

Oxytalan.

Not mature elastin

134
Q

Which orientation do elastic fibers in the PDL run?

A

Oxytalan fibers run vertically from cementum to the tooth apex, terminating the neurovascular complex and regulating vascular responses of the PDL

135
Q

True or false.. the PDL is avascular

A

False… it is rather well vascularized

Arterioles penetrate the cribriform plate. Posterior teeth have more vasculature than anterior. Mandibular teeth have more vasculature than the maxilla

136
Q

Arteries occupy loose connective tissue bays in the PDL called ____

A

Interstitial areas

137
Q

Nerves in the PDL run in what directions?

A

Apically and through the cribriform plate

138
Q

Generally, nerve fibers in the PDL are greatest at the ___. The exception is….

A

Tooth apex

Exception: upper incisors - greater nerve density, especially in the coronal, labial part of the PDL

139
Q

What are the four types of nerve endings in the PDL?

A

Free nerve endings - heavily branched, most prevalent, nociceptive, mechanoreceptive

Ruffini’s corpuscles - bulbous dendritic endings. Associated with schwann cells and collagen fibers. Slow adapting mechanoreceptive fibers

Coiled nerve endings - mid region of PDL

Spindle nerve endings - surrounded by a fibrous capsule. Found apically and are rare

*note that there is sympathetic innervation of the vasculature

140
Q

What are the 5 main histological groups of PDL fibers?

A 
Alveolar crest group
Horizontal group
Oblique group
Apical group
Interradicular group
141
Q

Describe the alveolar crest group of PDL fibers

A

Attach just at the CEJ and run outward to attach into the alveolar socket rim

142
Q

Describe the horizontal group of PDL fibers

A

Run from cementum at a right angle to the tooth into the alveolar socket

143
Q

Describe the oblique group of PDL fibers

A

Most numerous, run at an oblique angle from the cementum most of the way down the root

144
Q

Describe the apical group of PDL fibers

A

From the root apex to the underlying bone

145
Q

Describe the interradicular group of the PDL fibers

A

Only on multi-rooted teeth. They attach to the interradicular septum

146
Q

The PDL fibers terminate in the cementum or alveolar bone and are attached to these structures via ____, which are embedded collagen fibers

A

Sharpey’s fibers

147
Q

True or false.. the gingival ligament can be considered part of the PDL

A

False

148
Q

What is the function of the gingival ligament?

A

Composed of collagen fibers

Give the tooth a connection to surrounding soft tissues and neighboring teeth

149
Q

What are the five groups of the gingival ligament?

A

Dentogingival group

Alveologingival group

Circular group

Dentoperiosteal group

Transseptal fibers

150
Q

Describe the dentogingival group of the gingival ligament

A

most numerous, run from cervical cementum to lamina propria of the free and attached gingiva

151
Q

Describe the alveologingival group of the gingival ligament

A

Run from the alveolar crest to the lamina propria to the free gingiva

152
Q

Describe the circular group of the gingival ligament

A

Circular band around the neck of the tooth. Attaches to the other fibers and the free gingiva

153
Q

Describe the dentoperiosteal group of the gingival ligament

A

Run apically from cementum to the periosteum of the outer cortical plate

154
Q

Describe transseptal fibers of gingival ligament

A

Run from cementum just under the junctional epithelium over the alveolar crest and into the cementum of an adjacent tooth.

*significant cause of orthodontic relapse

155
Q

HERS will give rise to…

A

Dentin

Detached HERS cells give rise to rests of Malassez

HERS induces follicle cells to form cementoblasts

156
Q

What is cementoid?

A

Unmineralized matrix that is secreted by cementoblasts that will later mineralize

157
Q

Describe the composition of cementum

A

50% inorganic (hydroxyapatite)

50% organic (90% collagen 1, 10% bone associated non-collagnous proteins)

Composition is very similar to bone

158
Q

Cementum is thinnest at the ___ and thicker at the ____

A

CEJ (20um-50um)

apex (150um-200um)

159
Q

Name four non-collagenous proteins

A

Bone sialoprotein

Osteopontin

Osteocalcin

Osteonectin

160
Q

Cells in the dental follicle become cementoblasts. The specifics are unclear, but there are two possibilities. What are the two possibilities?

A

HERS or dentin induces cells in the dental follicle to become cementoblasts

Some HERS cells become cementoblasts themselves

161
Q

What are cementicles?

A

Abnormally large stones by root. Similar to enamel pearls

162
Q

HERS cells that break off become ____

A

Cell rests of malassez

163
Q

HERS cells that remain attached to roots can form ___

A

Enamel pearls

164
Q

Describe the three variations of the cementoenamel junction and their prevalence

A

Cementum overlaps enamel (60%)

Cementum and enamel meet at a blunt end (30%)

Cementum and enamel do not meet and form a gap exposing dentin (10%)

165
Q

What are the two subtypes of cementum? Where would you find each of these types in the tooth?

A

Acellular (primary) - coronal 2/3 of root

Cellular (secondary) (you will find trapped cementoblasts in secondary cementum) - apical 1/3 of root

166
Q

What is the difference between extrinsic and intrinsic fibers in the PDL? Which types of cementum has each?

A

Extrinsic = collagen fibers from PDL

Intrinsic = collagen fibers from the cementoblasts themselves

Acellular - extrinsic

Cellular - intrinsic

167
Q

What is the difference in the orientation of the extrinsic vs intrinsic fibers of the PDL?

A

Extrinsic go from PDL to cementum

Intrinsic run perpinducular to the PDL

168
Q

Describe the formation of AEFC

A

Predentin forms in the roots

Cementoblasts send processes into this predentin and produce collagen fibers

Mineralization occurs internally in the dentin and spreads into the cementum

Mingling occurs between dentin and cementum because dentin projects mineralization into the cementum while the cementum projects collagen into the dentin

After 15-20um of deposition, collagen synthesis stops, and only non-cllagenous protein is produced

Collagen fibers from the developing PDL fibroblasts merge with the fibrous fringe and mineralization occurs forming sharpey’s fibers

Cementoblasts end up only on the surface of the cementum (hence acellular)

169
Q

Describe the CIFC formation

A

Starts very similar to AEFC, with the intermingling to create the CDJ

Cementoblasts become entrapped in the advancing cementum to become cementocytes

Forms lucanae as in bone, but not as complex

Initial phase of rapid cementum production, followed by a slower more regular deposition

Cementoid is visible at the surface

170
Q

True or false… inner cementoblasts are vital

A

False because there is no vasculature to support them

171
Q

True or false… the collagen fibers present in CIFC are produced by cementoblasts, not PDL fibroblasts

A

True (hence intrinsic)

172
Q

Name some differences between AEFC and CIFC

A

AEFC: no cells inside. No cementoid. Slower deposition. More mineralized. Functions to attach the PDL to cementum

CIFC: cells inside. More laminar. Cementoid present. Often absent in anterior teeth. Functions to provide some attachment and to allow adjustment and adaptation to wear

173
Q

What is intermediate cementum?

A

Located between granular layer of tomes and dental cementum proper

Higher level of mineralization

May function to seal the surface of root dentin, which reduces sensitivity

174
Q

What is mixed cementum?

A

Alternating layers of AEFC and CIFC

Extrinsic and intrinsic fibers, generally located apically

Perhaps quite a lot of the secondary cementum is actually mixed

175
Q

What is hypercementosis?

A

Abnormal thickening of cementum

Diffuse or circumferential around the whole root

Can affect entire dentition, single tooth, or portions of one tooth.

Tooth can become ankylosed

176
Q

True or false… cementum is more resistant to resorption than alveolar bone

A

True

177
Q

The periodontium is generally affected by five types of tooth movements. What are they?

A 
Tipping
Bodily movement 
Extrusive movement 
Intrusive movement 
Rotational movement
178
Q

What are three factors that determine the degree of the effect of the applied force?

A

Transduction - efficiency of the conversion of physical force into biologic response

Time - effect is time-dependent

Magnitude of force - degree of force determines response

179
Q

What are the four net results of tooth movement?

A

Compression - on the side toward which the tooth moves. Results in resorption of alveolar bone

Tension - on the side opposite to compression. Results in formation of alveolar bone

Hyalinization - results from too great or too rapid a compression force. Loss of cell activity and vascularity

Undermining resorption - occurs in conjugation with hyalinization. Resorption occurs to the opposite surface of compressed bone (instead of deposition)

180
Q

Although there is some disagreement on the origin of salivary glands, most say that salivary glands are of ___ origin. This is supported by the fact that ___ is required for the formation of salivary glands.

A

Ectodermal

P63

181
Q

If someone has ____, they will have functional absence of salivary glands

A

Ectodermal dysplasia

182
Q

What are the 5 stages of salivary gland development

A

Prebud

Initial bud

Pseudoglandular (branching begins)

Canalicular (lumens begin to form)

Terminal bud

183
Q

True or false… although the salivary gland requires salivary mesenchyme and epithelium, all of the signals necessary for salivary gland development are from the mesenchyme

A

True

184
Q

What signals are involved in the initial bud and pseudoglandular stages?

A

FGF10

EDAR

185
Q

What signals are involved in the canalicular stage of salivary gland development?

A

FGF2b (no salivary gland development without this signal)

EDAR (helps form lumens)

186
Q

What is laminin 111

A

Expressed in embyologic developing salivary glands, but not found in adult glands. When laminin 111 is used in hydrogel, it will allow salivary gland regeneration

187
Q

Which stage of salivary gland development is the first stage in which lumens begin to form

A

Canalicular stage

188
Q

What signaling factors are found during the terminal bud stage?

A

EGF levels are high***

EGFR

TGF-alpha

BMP7

189
Q

True or false… mucins are present in the terminal bud stages

A

True

Mucin E17

Mucin transcript E14

190
Q

Describe the timeline of the development of salivary glands in weeks

A

Prebud 2-5 weeks

Initial bud 6-8 weeks

Pseudoglandular 9 weeks

Canalicular 10 weeks

191
Q

True or false… there is parasympathetic innervation of salivary glands before birth (necessary for development) but sympathetic innervation doesn’t occur until after birt

A

True

192
Q

Describe the innervation of the salivary glands

A

Sympathetics coming from the cervical ganglion innervate all of the salivary glands with the norepinephrine NT

Parasympathetics come from two sources. Glossopharyngeal nerve innervates the parotid gland through the otic ganglion . Facial nerve innervates submandibular and sublingual through the submandibular ganglion

193
Q

True or false.. salivary gland development occurs mostly at the pre-natal phase, but some growth continues after birth

A

True

194
Q

How can you tell the difference (histologically) between a mucous cell and a serous cell in a salivary gland?

A

Mucous cell nuclei are flattened to make room for the extensive ER

195
Q

You need both sympathetic and parasympathetic innervation to produce saliva. Sympathetic produces ___ whereas the parasympathetic produces ___

A

Proteins

Water

196
Q

In the parasympathetic response, the NT ____ binds to the ____ receptor to activate the G protein to activate the enzyme _____ to release the secondary messenger _____ to release ____ from the ER which will in turn….

A

acetylcholine

M3R (muscarinic recpetor)

PLC (phospholipase C)

IP3

Calcium

Open ion channels (sodium and chloride)

197
Q

In the sympathetic pathway, the NT ___ will bind to an ____ receptor. This will activate the G protein to activate the ____ enzyme, resulting in the second messenger ____ which will function to….

A

Norepinephrine

Adrenergic

Adenylyl cyclase

CAMP

Release proteins out the apical end

198
Q

What are the two stages in saliva production?

A

Hypertonic

Hypotonic

199
Q

What are the functions of tight junctions in the acinus of salivary glands?

A

They prevent backflow of water from the basolateral side

200
Q

Which ducts in salivary glands have cells that have lots of mitochondria in their villi? These ducts are also impermeable to water

A

Striated ducts

201
Q

Bicarbonate is pumped out of salivary gland cells through the ____ side

A

Apical side into the lumen

202
Q

The main way to draw water into the lumen of the acinus of salivary glands is…

A

By pumping chloride into the lumen. Sodium and water follow

203
Q

What is the name of the apical chloride channel and apical water channel

A

Tmem16A

Aqp5

204
Q

Name the five types of channels found on the basolateral side of the acinus

A

Na/k/2Cl cotransporters

k channels

Na/H exchangers

Cl/HCO3 exchangers

Na/K ATPase

205
Q

What occurs in the second stage of saliva secretion? What channels are involved?

A

NaCl reabsorption and K secretion

Na channels
Cl channels (CFTR***)
K channels
Cl/HCO3 exchangers
206
Q

What are the three methods of protein secretion in salivary glands?

A

Constitutive pathway - no NT involved

Contstitutive-like pathway

Major regulated pathway

Minor regulated pathway

207
Q

Describe the composition of saliva

A

99.55% water
PH = 7

Buffer with bicarbonate and phosphate

Mucins for lubrication

Amylase for carbohydrate digestion

Lectoferrin and lysozyme for antimicrobial activity

208
Q

Saliva is initially produced in the ___, then flows through the ___ duct into the ___ duct

A

Acinus

Intercalated

Striated

209
Q

What are some conditions that affect salivary function?

A

Ectodermal dysplasia

Autoimmunity

Sjogrens syndrome

Irradiation side effects

Drug side effects

Diabetes, sarcoidosis, cystinosis, head/neck neoplasms, systemic sclerosis, rheumatoid arthritis, psychosis, tumors, thyroid disease, malnutrition

210
Q

True or false… basolateral transporters concentrate chloride above its electrochemical gradient

A

True

211
Q

True or false… protein secretion occurs as a complete fusion of secretory granules at the basolateral membrane

A

False. The apical membrane

Oral Biology (4 decks)

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