Exam 2

Question 1

Percentages of dentin:
Mineral: ?
Organic: ?
Water: ?

Answer 1

Mineral: 70%
Organic: 20%
Water: 10%

Question 2

How does Type 1 Collagen of dentin differ than that in bone?

Answer 2

• higher ratio of proline and hydroxyproline
• Higher prevalence of molec crosslinking
• more bound to water

Question 3

What structure located in what part of the enamel organ stimulates osteoblast differentiation?

Answer 3

fibronectin in the basal lamina of inner enamel epithelium

Question 4

What are the four growth factors secreted by the IEE?

Answer 4

• Transforming Growth Factor (TGF)
• Bone Morphogenetic Protein (BMP)
• Insulin-like Growth Factor (IGF)
• Fibroblast Growth Factor (FGF)

Question 5

How thick is mantle dentin?

Answer 5

50-100 micrometers

Question 6

What are lines of von Ebner?

Answer 6

hesitation in matrix formation every 4-20 days that show has hypomineralization of dentin

Question 7

Dentin tubule diameter at pulpal surface vs the DEJ?

Answer 7

Pulpal surface: 2.5 micrometers

DEJ: 0.9 micrometers

Question 8

What is bad about interglobular dentin? Where is it often found?

Answer 8

• nothing wrong, formed by hypomineralized area in between normal areas
• in dentin in crowns

Question 9

What is Tome’s Granular Layer?

Answer 9

-granular appearing layer of dentin adjacent to cementum

Question 10

Define primary and secondary dentin

Answer 10

Primary: dentin (except mantle dentin) formed up to the time of functional occlusion
Secondary: dentin (except tertiary dentin) formed after tooth achieves functional occlusion

Question 11

Where does tertiary/reparative dentin come from?

Answer 11

-subodontoblastic layer

Question 12

Where do the growth factors that affect the subodontoblastic layer come from?

Answer 12

the pulp

Question 13

What condition lead to bluish opalescent teeth with normal enamel?

Answer 13

Dentinogenesis imperfecta

Question 14

What condition can lead to teeth having no pulp chambers?

Answer 14

Dentinogenesis imperfecta

Question 15

What does fluoride replace in hydroxyapatite crystals?

Answer 15

hydroxyl ions

Question 16

What are the 5 bacteria thought to be responsible for caries?

Answer 16

1. Streptococcus mutans
2. Streptococcus sorbrinus
3. Streptococcus gordonii
4. Lactobacillus acidophilus
5. Actinomyces viscosus (root caries)

Question 17

What teeth are most commonly affected by dentinal sensitivity?

Answer 17

Canines and premolars

Question 18

The Brannstrom’s Hydrodynamic Theory of dentin sensitivity is based on what law of physics?

Answer 18

Charles’ Law (volume of gas or liquid is directly proportional to heat applied at constant pressure

Question 19

At what stage of tooth development does pulp start forming?

Answer 19

Cap Stage

Question 20

When do capillaries start developing in the pulp?

Answer 20

Bell Stage

Question 21

What is the origin of pulpal cells?

Answer 21

Ectomesenchymal neural crest cells

Question 22

What are the two compartments of the pulp?

What is in each compartment?

Answer 22

• Odontogenic Zone: odontoblast cell layer, cell-free zone of Weil, Cell-rich zone, parietal plexus of nerves (Raschkow’s plexus)
• Pulpal Core: Fibroblasts, Type I and II collagen, extracellular matrix, blood vessels, nerve tissue

Question 23

What are the functions of dental pulp?

Answer 23

Embryonic induction, formative, protective, reparative

Question 24

What are the non-collagenous matrix components of pulp?

Answer 24

• proteoglycans
• glycosaminoglycans
• phosphoproteins
• glycoproteins
• gamma-carboxyglutamate-containing proteins

Question 25

What CN branch innervates the pulp? (sensory and motor)

Answer 25

CN V (Trigeminal)

Question 26

What are the classifications of the sensory nerve fibers ni the pulp?

Answer 26

- fast: A-delta for sharp pain, large diameter | - slow: C for dull pain, narrow diameter

Question 27

How many branches does each nerve fiber contribute to Raschkow's Plexus?

Answer 27

at least 8

Question 28

A majority of nerve axons are in the ______ of the pulp horns, remaining crown, and root.

Answer 28

predentin

Question 29

Part of tooth with least amount of blood vessel branching

Answer 29

root apex

Question 30

Do pulp venules or arterioles have a larger lumen?

Answer 30

Venules (100-150) Arterioles (50-100)

Question 31

Why might pulp die due to age?

Answer 31

Pulpal hypoxia due to bood deprivation caused by cholesterol plaques in bv

Question 32

What two things cause pulpal fibrosis?

Answer 32

Increasing age or persistent low-grade inuury like multiple restorations, bruxism, or repeated thermal insult

Question 33

Why might someone have calcified deposits along collagen fiber bundles or in blood vessels in the pulp?

Answer 33

Chronic low grade inflammation can cause diffuse calcifications

Question 34

Difference between true and false denticles

Answer 34

True has dentin tubules. False don't have tubules and have concentric layers of calcified tissue.

Question 35

Where might you see vacuolated or syncytial macrophages?

Answer 35

In a dental abscess.

Question 36

If pulpal necrosis expands to the alveolar bone then to muscle tissue, what condition may occur?

Answer 36

Diffuse cellulitis

Question 37

Functions of the GFL: 5 of them PAPAI

Answer 37

- provide rigidity to marginal gingiva - act as periosteum for interproximal crestal alveolar bone - provide 1/2 of biologic width - act as protective barrier to spread of gingival inflammation - inhibit apical migration of junctional epithelium

Question 38

What is the biologic width?

Answer 38

Area of junctional epithelium and gingival fiber attachment to the root of the tooth. Violation of this width due to overextended margins will cause chronic inflammation and alveolar bone loss to restore 2mm required width

Question 39

What are the 5 functions of the PDL?

Answer 39

1. Supportive 2. Regenerative (self, and helps w/ cementum and bone repair) 3. Nutritional (via blood vessels) 4. Sensory 5. Protective (cushions tooth)

Question 40

What are the 5 functions of the PDL?

Answer 40

1. Supportive 2. Regenerative (self, and helps w/ cementum and bone repair) 3. Nutritional (via blood vessels) 4. Sensory 5. Protective (cushions tooth)

Question 41

During tooth development, the PDL comes from ____ which is derived from _____ _____ cells.

Answer 41

- the dental follicle | - neural crest

Question 42

The three layers of the dental follicle make what three PDL associated structures?

Answer 42

Outer Zone: Alveolar bone Intermediate Zone: PDL Inner Zone: cementum

Question 43

What two groups of PDL fibers appear to form first in development?

Answer 43

DGF and DPF

Question 44

What are principle fibers?

Answer 44

Collagen fibers that are embedded into the cementum. (Sharpey's Fibers)

Question 45

What supports the principle fibers?

Answer 45

Indifferent fiber plexus

Question 46

Would interradicular fibers be found in anterior teeth?

Answer 46

No (unless there was a multirooted tooth)

Question 47

What fibers are responsible for orthodontic relapse?

Answer 47

- Transseptal - Semicircular - PDL principle fiber groups

Question 48

What is found in the interstitial spaces of the PDL?

Answer 48

- blood vessels | - undifferentiated cells

Question 49

If an injury is significant enough to involve alveolar bone? How does it repair?

Answer 49

Akylosis due to vascular bone being the primary repair mechanism. If the interstitial spaces are not injured, then the PDL can repair itself.

Question 50

If an injury is significant enough to involve alveolar bone? How does it repair?

Answer 50

Akylosis due to vascular bone being the primary repair mechanism. If the interstitial spaces are not injured, then the PDL can repair itself.

Question 51

Why is a membrane needed to stimulate proper healing of bone loss?

Answer 51

Prevents migration of epithelial tissue from gingiva. Allows differentiation of mesenchymal cells in interstitial spaces of PDL and marrow spaces of adjacent alveolar bone

Question 52

What is the origin of the epithelial rests of malassez?

Answer 52

Hertwig's Rooth Sheath

Question 53

Lateral periodontal cysts are thought to come from....

Answer 53

epithelial rests of mallesez

Question 54

Gingival cysts are derived from _________ rests of ________. And are remnants of the ______ _______.

Answer 54

- epithelial rests of serres | - dental lamina

Question 55

What is the average width of the PDL in an adult?

Answer 55

about 0.17 mm

Question 56

What is more similar in organic vs mineral composition? Dentin and bone or cementum and bone?

Answer 56

Dentin and bone have similar composition. Cementum is about 50:50 organic and mineral

Question 57

How much thicker is cementum at the apex than at midroot?

Answer 57

twice as thick at the apex

Question 58

What layer of the dental follicle leads to the cementum?

Answer 58

Inner

Question 59

What causes differentiation of the undifferentiated mesenchymal cells in the follicle to turn into cementoblasts?

Answer 59

Perforations in Hertwig's Root Sheath allow those cells to contact the dentin where dentin growth factors stimulate differentiation.

Question 60

How are cementocytes and osteocytes similar?

Answer 60

Both have lacunae and canaliculi

Question 61

Percentages of CEJ overlap, end-to-end, and gap.

Answer 61

Overlap: 60% E2E: 30% Gap: 10%

Question 62

Difference between abrasion and erosion?

Answer 62

Abrasion is due to friction and erosion is due to chemical wear

Question 63

Where can cementicles be found?

Answer 63

Calcified bodies similar to denticles. Can be found in cementum or PDL

Question 64

What is bad about exposed cementum?

Answer 64

- it becomes hypermineralized so PDL collagen cannot reattach. - facilitates attachment of biofilm

Question 65

What area of the root is most affected by hypercementosis?

Answer 65

apical 1/3

Question 66

Where is the most likely place to see accessory root canals in multirooted and then single rooted teeth?

Answer 66

Multirooted: 28% at furcation Single: 17% at apex (8.8% in middle, 1.6% in coronal portion of root)