Exam 3 Flashcards
(211 cards)
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
2
Q
Describe the composition of dentin.
Inorganic material
Organic material
Water
A
Inorganic material: 70%
Organic material: 20%
Water 10%
3
Q
What makes up the inorganic material of dentin?
A
Hydroxyapatite
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
5
Q
Describe what the HA crystals look like in dentin
A
HA crystals are flattened in rectangular plates along collagen
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
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)
8
Q
The collagen in dentin is mostly type ___, some ___ and ___
A
1 (similar to bone)
3
5
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
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
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
12
Q
DSPP is cleaved by ___ to form ___, ___, and ___
A
BMP-1
DSP
DGP
DPP
13
Q
What is DSP (dentin sialoprotein)?
A
Proteoglycan
Prevents mineralization in dentin tubules*
Similar to DMP -1
14
Q
What is DGP?
A
Dentin glycoprotein
Role unknown, but may be involved in biomineralization by causing nucleation of HA crystals
15
Q
What is DPP?
A
Dentin phosphoprotein
Initiates HA formation (binds lots of HA)*
Attached to collagen
Not glycosylated
16
Q
Defects in DSPP can cause ___
A
Dentinogenesis imperfecta types 2 and 3
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”)
18
Q
Odontoblasts have ____ origin
A
Mesenchymal
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
20
Q
Which is active first, coronal or apical odontoblasts?
A
Coronal odontoblasts are activated before apical odontoblasts
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
22
Q
What provides the attachement of dentin to enamel in the DEJ?
A
Mineral components are intermingled
23
Q
The first layer of dentin is called ____ and is closest to the DEJ.
A
Mantle dentin
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
25
Describe the early formation of dentin
Developing odontoblasts extend Tome's fibers into developing matrix and secrete dentin matrix components in matrix vesicles
26
Penetration of dentin fibers into the IEE are called ____
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
27
Early dentin (predentin) is ____ organic matrix
Non-mineralized
28
What are seed crystals? Describe dentin formation
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)
29
What is circumpulpal dentin?
All of the dentin that is not mantle dentin
30
Cell rests of malassez are derived from _____
HERS (hertwig's root sheath)
Note that HERS also initiates odontoblast differentiation in the root
31
What are the differences between primary and secondary dentin?
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
32
What is the difference between coronal and root dentin tubules?
Coronal dentin: tubules have a sigmoidal curve
Root dentin: tubules are much straighter
33
Secondary dentin deposition is greater around the ____ and ____ than ____
Roof and floor than the sides
34
What is tertiary dentin? Does it have tubules?
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
35
Why is tertiary dentin also called osteodentin?
It resembles bone more closely than other types of dentin do
36
What is the difference between reactionary and reparative tertiary dentin?
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
37
What are the three main macro structures of dentin?
Dentin tubules (with OD process)
Peritubular dentin (lines the tubules) (highly calcified)
Intertubular dentin (collagen 1 fibrils are arranged perpendicular to tubules)
38
What are dentinal tubules?
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
39
What are dead tracts in regards to caries and dentin?
Trapped air in empty tubules - sealed off after odontoblasts death
Appear black in ground section
40
What is sclerotic dentin?
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
41
What is interglobular dentin?
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
42
Dentin matrix is deposited continually at approximately ___ per day
4 microns
43
What are lines of von Ebner?
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
44
What are contour lines of Owen?
Enhanced lines that indicate disruption of tooth formation
Equivalent to stria of retzius in enamel
45
What is the granular layer of Tomes?
"Funny looking dots" that are located around the roots of ground sections
Gets more granular toward the apical end.
46
What are three possible reasons for the formation of the granular layer of tomes?
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
47
What is the primary cell type of dental pulp?
Fibroblasts followed by odontoblasts
48
What are some components of the dental pulp?
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
49
Name the four histological zones form outer to inner of the dental pulp
Odontoblast layer
Cell free zone of Weil
Cell rich zone
Pulp core
50
The soft CT matrix of the dental pulp is mostly comprised of collagen ____, but also some ____. There are also ____ and ____ which contribute to squidginess
3
1
Proteoglycans
Glycoproteins
51
What happens to dental pulp ECM as it ages?
Collagen content increases and fibrils aggregate into larger bundles, greatest concentration apically
Squidgyness decreases with age
52
What comprises the ground substance of the pulp?
Proteoglycans (GAG chains, glycoproteins, water
53
Name 5 proteoglycans found in pulp (dont stress about his too much, he says we dont really have to know it)
Chondroitin 6 sulfate
Chondroitin 4 sulfate
Heparin sulfate
Dermatan sulfate
Keratin sulfate
54
Odontoblasts are more ____ in shape in the crown, whereas they are more ____ in shape in the root.
Columnar
Cuboidal
55
How are odontoblasts held together? Why is this significant?
Junctional complexes
Adherens junctions
This is significant because it may give a degree of permeability to the OD layer
56
Odontoblasts can form _____ with pulpal fibroblasts
Gap junctions
This allows the fibroblasts in the pulp to respond to external conditions
57
True or false... odontoblasts only lay down collagen
False... they also lay down non-collagenous protein
58
Describe aged odontoblasts
Fewer organelles
Less secretory activity
Nucleus somewhat more central
59
How are odontoblasts regenerated?
Can be replaced from mesenchymal progenitor pool
Sequestered growth factors in dentin matrix
60
What is the predominant cell type found in the dentin-pulp complex? Where is it found?
Fibroblasts
Pulp core and cell rich zone
61
Where are macrophages and dendritic cells found in the tooth?
Macrophages present in dental pulp
Dendritic cells found under odontoblast layer
62
When will you find lymphocytes in the pulp?
Low numbers normally. Higher numbers in infected pulps
63
Pulp vasculature arises from the ____ arteries, which will ultimately branch into the ___ and ____ arteries
External carotid
Superior/inferior alveolar
64
There are about ___ - ___ arterioles per tooth that enter the apical foramen
4-8
65
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?
Cell free zone
During primary dentin formation, they are found in the odontoblast layer
66
True or false... in the tooth the lymphatic drainage is equal to arterial interstitial flow
True
67
In the pulp, nerve fibers branch out through the coronal pulp forming the plexus of ____
Raschkow
| Found especially under cusps
68
True or false... in root pulp there are no plexuses of Raschkow
True. There are only branches of nerve fibers
69
What are the nerve sources for the innervation of the pulp?
Afferent nerves coming from trigeminal
Sympathetic branches come from the superior cervical ganglion
70
Nerve bundles consist of both ___ and ___ axons
Myelinated alpha delta
Unmyelinated C
71
Myelination decreases as fibers proceed towards the ____
Coronal pulp
72
True or false... some unmyelinated nerve axons pass into the dentinal tubules
True
73
What are the three proposed models of dentin sensitivity? Describe the reasoning behind each model.
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
74
Mineralized tissue can form inappropriately in the pulp (pulp stones). Describe the four types
Free
Surrounding by soft pulp tissue
Attached to dentin
Embedded in secondary dentin
75
Pulp stones are likely to occur around....
Collagen fibers
Dead cell aggregates
Thrombi
(More prevalent after 50 years of age)
76
What are some age related changes in pulp?
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)
77
Name and describe the five types of physiologic tooth movements
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)
78
Preeruptive tooth movements take case in a ____ and thus are associated with bone ___ and/or ___
Boney crypt
Resorption
Deposition
79
What is the difference between bodily movement and directional/eccentric growth?
Bodily movement - increase in length
Directional/eccentric growth - increase in height
80
What occurs with the oral epithelium when primary teeth erupt?
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
81
What is the gubernacular canal? The gubernacular canal forms along the remnants of the ____ attached to the lamina propria
A channel that develops between the alveolar bone around the primary tooth and the permanent tooth as it erupts.
Dental lamina
82
How fast do permanent teeth move through bone? How fast do they move through the gubernacular canal?
Intraosseous: 1-10 um/day
Gubernacular canal: 75 um/day
83
What are the four theories of tooth eruption?
Bone remodeling theory
Root growth theory
Vascular pressure theory
Fusion hammock theory
84
Describe the bone remodeling theory. What are two problems in regards to this theory?
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
85
Describe the root growth theory. Name three problems in regards to this theory.
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
What is the vascular pressure theory? Name two problems in regards to this theory
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
What is the cushion hammock theory? What is a problem regarding this theory?
A magic ligament under the tooth pushes it out
Problem: "like eleven, pixies, and true happiness, this ligament most likely doesn't exist"
88
Currently, it is thought that the ____, developing after root formation, is the driving force for tooth eruption.
Periodontal ligament
89
How does the PDL help the tooth erupt?
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
The ____ is critical for tooth eruption, as it initiates bone resorption and the breakdown of soft tissues allowing for eruption
Dental follicle
91
What are the key mediators of eruption to cause tissue resorption in bone, connective tissue, and epithelium?
Colony stimulating factor-1
Interleukin 6
Interleukin 1a
Monocyte chemotactic protein-1
92
What are the key mediators for eruption involved in tissue formation?
BMP - 2
BMP - 6
Runx2
TGF-beta
EGF
93
What is the purpose of post eruptive tooth movement?
To accommodate the growing jaws
Compensate for occlusal wear
Compensate for interproximal wear
94
In regards to orthodontic tooth movement, compression of bone will ___ bone whereas pulling on bone will ____ bone
Resorb
Deposit
95
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
True
96
What is hyalinization?
Damage to cells in the PDL, loss of cells = no remodeling
97
The PDL functions to ____ whereas the deposition of new cementum/alveolar bone functions to ___
Keep the tooth in occlusion
Keep the tooth in its new adjusted position
98
Post eruptively, teeth tend to move mesial or distal due to pressure?
Mesial
If you load the back teeth, they are going to push the anterior teeth together in a mesial fashion
99
The hard tissues of the tooth (namely dentin/cementum) are resorbed by the action of ___
Odontoclasts
100
True or false.. primary teeth will not shed without a succeeding permanent tooth.
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
What are the combination of factors that lead to shedding of primary teeth?
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
Whose teeth typically erupt first, girls or boys?
Girls
103
What is the order of eruption of secondary teeth from anterior to posterior teeth in the maxillary arch?
781-0062
104
What is the order of eruption of secondary teeth from anterior to posterior teeth in the mandibular arch?
679-0161
105
What are the three principle components of the periodontium?
Alveolar process
Cementum
Periodontal ligament
106
The periodontium develops during a series of complex interactions of ___, ___, and ____
Mesenchyme
HERS
Dental follicle
107
What is a gomphosis?
Fibrous peg-in-socket joint
108
The alveolar process is formed by ___ ossification, beginning in the ____ week of uterine life
Intramembranous
109
____ develop around tooth germs, such that they eventually form the sockets
Crypts
110
The alveolar process develops substantially during ___
Tooth eruption, under the influence of the dental follicle
111
What are anodontic individuals?
Alveolar process development is impaired
112
What is the difference between alveolar bone proper and supporting alveolar bone?
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
What kind of canals run through the cribriform plate in the alveolar bone proper?
Volkmann's canals. (Arterioles run through vokmann's canals)
114
What is the lamina dura?
Radiographic term for the area of PDL attachment
115
What is bundle bone?
Histological term referring to sharpey's fibers (collagen fibers of PDL) embedded in bone)
116
Is the inner alveolar bone proper (towards PDL) primarily consisting of woven bone or lamellar bone?
Woven bone (more collagen 3) because it is more dynamic due to the constant adaptation of tooth. Lamellar bone is also present though
117
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
True
118
What is the alveolar crest?
Junction of cortical plate and alveolar bone proper
119
Where is alveolar bone the thinnest and thickest?
Thinnest in maxilla
Thickest in premolar and molar region of mandible
120
True or false the central spongiosa is more prevalent in the maxilla than the mandible
True
121
True or false... the central spongiosa is more distinguished in the anterior portion of the jaws as opposed to the posterior portion
False. It is absent/diminished in the anterior region
122
What is the difference between the interradicular septum and the interalveolar septum?
Interradicular septum - bony septum between roots of a single tooth
Interalveolar septum - bony septum between adjacent teeth
123
What are the four functions of alveolar bone?
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
When does the PDL develop in reference to when cementum and the alveolar process develops?
At the same time
125
The PDL develops after detachment of ___
HERS
126
Fibroblasts produce and organize PDL collagen fibers, generally in an oblique orientation orientation. Where are these fibroblasts derived from?
Ectomesenchyme cells from the dental follicle
127
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
True
128
What cells are associated with PDL?
```
Fibroblasts
Mesenchymal cells
Epithelial cells
Macrophages
Osteoblasts
Osteoclasts
Cementoblasts
```
129
The PDL ranges in width between ___ mm and ___ mm
.15mm and .38mm
130
The width of the PDL ____ with age because...
Decreases
Because cementum increases in thickness, closing off the width. also perhaps masticatory forces decrease
131
What type of collagen is present in the PDL?
1
3
7
132
True or false... when the PDL undergoes remodeling, entire bundles are changed at a time.
False... individual fibers are remodeled whilst the overall bundle is not changed, making a very dynamic environment
133
What is the main elastic fiber of the PDL
Oxytalan.
| Not mature elastin
134
Which orientation do elastic fibers in the PDL run?
Oxytalan fibers run vertically from cementum to the tooth apex, terminating the neurovascular complex and regulating vascular responses of the PDL
135
True or false.. the PDL is avascular
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
Arteries occupy loose connective tissue bays in the PDL called ____
Interstitial areas
137
Nerves in the PDL run in what directions?
Apically and through the cribriform plate
138
Generally, nerve fibers in the PDL are greatest at the ___. The exception is....
Tooth apex
Exception: upper incisors - greater nerve density, especially in the coronal, labial part of the PDL
139
What are the four types of nerve endings in the PDL?
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
What are the 5 main histological groups of PDL fibers?
```
Alveolar crest group
Horizontal group
Oblique group
Apical group
Interradicular group
```
141
Describe the alveolar crest group of PDL fibers
Attach just at the CEJ and run outward to attach into the alveolar socket rim
142
Describe the horizontal group of PDL fibers
Run from cementum at a right angle to the tooth into the alveolar socket
143
Describe the oblique group of PDL fibers
Most numerous, run at an oblique angle from the cementum most of the way down the root
144
Describe the apical group of PDL fibers
From the root apex to the underlying bone
145
Describe the interradicular group of the PDL fibers
Only on multi-rooted teeth. They attach to the interradicular septum
146
The PDL fibers terminate in the cementum or alveolar bone and are attached to these structures via ____, which are embedded collagen fibers
Sharpey's fibers
147
True or false.. the gingival ligament can be considered part of the PDL
False
148
What is the function of the gingival ligament?
Composed of collagen fibers
Give the tooth a connection to surrounding soft tissues and neighboring teeth
149
What are the five groups of the gingival ligament?
Dentogingival group
Alveologingival group
Circular group
Dentoperiosteal group
Transseptal fibers
150
Describe the dentogingival group of the gingival ligament
most numerous, run from cervical cementum to lamina propria of the free and attached gingiva
151
Describe the alveologingival group of the gingival ligament
Run from the alveolar crest to the lamina propria to the free gingiva
152
Describe the circular group of the gingival ligament
Circular band around the neck of the tooth. Attaches to the other fibers and the free gingiva
153
Describe the dentoperiosteal group of the gingival ligament
Run apically from cementum to the periosteum of the outer cortical plate
154
Describe transseptal fibers of gingival ligament
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
HERS will give rise to...
Dentin
Detached HERS cells give rise to rests of Malassez
HERS induces follicle cells to form cementoblasts
156
What is cementoid?
Unmineralized matrix that is secreted by cementoblasts that will later mineralize
157
Describe the composition of cementum
50% inorganic (hydroxyapatite)
50% organic (90% collagen 1, 10% bone associated non-collagnous proteins)
Composition is very similar to bone
158
Cementum is thinnest at the ___ and thicker at the ____
CEJ (20um-50um)
apex (150um-200um)
159
Name four non-collagenous proteins
Bone sialoprotein
Osteopontin
Osteocalcin
Osteonectin
160
Cells in the dental follicle become cementoblasts. The specifics are unclear, but there are two possibilities. What are the two possibilities?
HERS or dentin induces cells in the dental follicle to become cementoblasts
Some HERS cells become cementoblasts themselves
161
What are cementicles?
Abnormally large stones by root. Similar to enamel pearls
162
HERS cells that break off become ____
Cell rests of malassez
163
HERS cells that remain attached to roots can form ___
Enamel pearls
164
Describe the three variations of the cementoenamel junction and their prevalence
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
What are the two subtypes of cementum? Where would you find each of these types in the tooth?
Acellular (primary) - coronal 2/3 of root
Cellular (secondary) (you will find trapped cementoblasts in secondary cementum) - apical 1/3 of root
166
What is the difference between extrinsic and intrinsic fibers in the PDL? Which types of cementum has each?
Extrinsic = collagen fibers from PDL
Intrinsic = collagen fibers from the cementoblasts themselves
Acellular - extrinsic
Cellular - intrinsic
167
What is the difference in the orientation of the extrinsic vs intrinsic fibers of the PDL?
Extrinsic go from PDL to cementum
Intrinsic run perpinducular to the PDL
168
Describe the formation of AEFC
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
Describe the CIFC formation
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
True or false... inner cementoblasts are vital
False because there is no vasculature to support them
171
True or false... the collagen fibers present in CIFC are produced by cementoblasts, not PDL fibroblasts
True (hence intrinsic)
172
Name some differences between AEFC and CIFC
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
What is intermediate cementum?
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
What is mixed cementum?
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
What is hypercementosis?
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
True or false... cementum is more resistant to resorption than alveolar bone
True
177
The periodontium is generally affected by five types of tooth movements. What are they?
```
Tipping
Bodily movement
Extrusive movement
Intrusive movement
Rotational movement
```
178
What are three factors that determine the degree of the effect of the applied force?
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
What are the four net results of tooth movement?
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
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.
Ectodermal
P63
181
If someone has ____, they will have functional absence of salivary glands
Ectodermal dysplasia
182
What are the 5 stages of salivary gland development
Prebud
Initial bud
Pseudoglandular (branching begins)
Canalicular (lumens begin to form)
Terminal bud
183
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
True
184
What signals are involved in the initial bud and pseudoglandular stages?
FGF10
EDAR
185
What signals are involved in the canalicular stage of salivary gland development?
FGF2b (no salivary gland development without this signal)
EDAR (helps form lumens)
186
What is laminin 111
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
Which stage of salivary gland development is the first stage in which lumens begin to form
Canalicular stage
188
What signaling factors are found during the terminal bud stage?
EGF levels are high***
EGFR
TGF-alpha
BMP7
189
True or false... mucins are present in the terminal bud stages
True
Mucin E17
Mucin transcript E14
190
Describe the timeline of the development of salivary glands in weeks
Prebud 2-5 weeks
Initial bud 6-8 weeks
Pseudoglandular 9 weeks
Canalicular 10 weeks
191
True or false... there is parasympathetic innervation of salivary glands before birth (necessary for development) but sympathetic innervation doesn't occur until after birt
True
192
Describe the innervation of the salivary glands
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
True or false.. salivary gland development occurs mostly at the pre-natal phase, but some growth continues after birth
True
194
How can you tell the difference (histologically) between a mucous cell and a serous cell in a salivary gland?
Mucous cell nuclei are flattened to make room for the extensive ER
195
You need both sympathetic and parasympathetic innervation to produce saliva. Sympathetic produces ___ whereas the parasympathetic produces ___
Proteins
Water
196
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....
acetylcholine
M3R (muscarinic recpetor)
PLC (phospholipase C)
IP3
Calcium
Open ion channels (sodium and chloride)
197
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....
Norepinephrine
Adrenergic
Adenylyl cyclase
CAMP
Release proteins out the apical end
198
What are the two stages in saliva production?
Hypertonic
Hypotonic
199
What are the functions of tight junctions in the acinus of salivary glands?
They prevent backflow of water from the basolateral side
200
Which ducts in salivary glands have cells that have lots of mitochondria in their villi? These ducts are also impermeable to water
Striated ducts
201
Bicarbonate is pumped out of salivary gland cells through the ____ side
Apical side into the lumen
202
The main way to draw water into the lumen of the acinus of salivary glands is...
By pumping chloride into the lumen. Sodium and water follow
203
What is the name of the apical chloride channel and apical water channel
Tmem16A
Aqp5
204
Name the five types of channels found on the basolateral side of the acinus
Na/k/2Cl cotransporters
k channels
Na/H exchangers
Cl/HCO3 exchangers
Na/K ATPase
205
What occurs in the second stage of saliva secretion? What channels are involved?
NaCl reabsorption and K secretion
```
Na channels
Cl channels (CFTR***)
K channels
Cl/HCO3 exchangers
```
206
What are the three methods of protein secretion in salivary glands?
Constitutive pathway - no NT involved
Contstitutive-like pathway
Major regulated pathway
Minor regulated pathway
207
Describe the composition of saliva
99.55% water
PH = 7
Buffer with bicarbonate and phosphate
Mucins for lubrication
Amylase for carbohydrate digestion
Lectoferrin and lysozyme for antimicrobial activity
208
Saliva is initially produced in the ___, then flows through the ___ duct into the ___ duct
Acinus
Intercalated
Striated
209
What are some conditions that affect salivary function?
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
True or false... basolateral transporters concentrate chloride above its electrochemical gradient
True
211
True or false... protein secretion occurs as a complete fusion of secretory granules at the basolateral membrane
False. The apical membrane
