Dental Anatomy, Histology, Physiology, and Occlusion

Question 1

Enamel formation is done via what process, and involves what cells?

Answer 1

Amelogenesis
Ameloblast

Question 2

What embryonic germ layer does ameloblast derive from?

Answer 2

ectoderm

Question 3

What location of the tooth has the thicker/thinner layer of enamel

Answer 3

Enamel is thicker at the incisal/occlusal areas and thins out until it reaches the CEJ (ranging 2-3mm in thickness)

Question 4

Cusps develop from individual _______.

Answer 4

ossification centers, which form into developmental lobes

Question 5

the separation of cusps result in _____ and ______.

Answer 5

grooves and fossae (areas of coalescence)

Question 6

A functional cusp that opposes a groove or fossa occludes where

Answer 6

on enamel inclines on each side of the groove and not in the depth of the groove (leaves a v shaped escape path between the cusp and its opposing groove for the movement of food during chewing)

Question 7

the failure/compromised coalescence of enamel results in

Answer 7

a fissure

Question 8

noncoalesced enamel at the deepest point of a fossa is termed

Answer 8

pit

Question 9

fissures and pits represent what type of areas

Answer 9

non-self-cleaning areas where acidogenic biofilm accumulates and predisposes the tooth to caries

Question 10

what is the largest mineral constituent of enamel

Answer 10

hydroxyapatite

Question 11

what is the % of hydroxyapatite in enamel

Answer 11

90-92%

Question 12

mineral constituent of enamel

Answer 12

hydroxyapatite (90-92%)
organic matrix protein (1-2%)
water (4-12%)

Question 13

Enamel rods

Answer 13

“prisms” that are the largest structural part of of enamel and are formed appositionally

Question 14

Appositional deposition of enamel rods are called?

Answer 14

Striae of retzius

Question 15

Lines of Pickerill

Answer 15

incomplete, alternatiting lines of retzius noticeable on the enamel surface

Question 16

Perikymata

Answer 16

space in between the lines of Pickerill that are parallel to the CEJ

Question 17

how many enamel rods are there?

Answer 17

5-12 million

Question 18

how are enamel rods positioned?

Answer 18

perpendicular to the DEJ EXCEPT in the cervical region of permanent teeth, where they are oriented outward in a slightly apical direction

Question 19

the cervical layer of the tooth is missing what? how are the hydroxyapatite crystals oriented?

Answer 19

the cervical layer of enamel is prism-less (known as prismless enamel), and crystals are parallel to one another and perpendicular to the striae of retzius

Question 20

enamel rods are formed by what cells

Answer 20

ameloblast

Question 21

what direction are enamel rods produced in

Answer 21

alternating clockwise and counterclockwise

Question 22

Why are enamel rods produced in alternating patterns

Answer 22

minimizes the fracture of then in the axial direction

Question 23

what is the term of the alternating deposition of bands in enamel

Answer 23

hunter-schreger bands

Question 24

what is the nasmyth membrane

Answer 24

a membrane layer that covers the ends of the enamel rods

Question 25

the nasmyth membrane is replaces by what structure

Answer 25

the pellicle and it is formed by salivary proteins

Question 26

apatite crystals are arrange how (what is the degrees of the arrangement)

Answer 26

65-degree angle parallel to the long axis of the

Question 27

what is the permeable route of transmission of ions and molecules within enamel

Answer 27

rod sheaths, enamel cracks

Question 28

enamel lamellae

Answer 28

thin, leaflike faults between the enamel rod groups and are mostly made of organic material and predispose the tooth to caries.

Question 29

enamel maturation

Answer 29

age-like maturation of the enamel matrix that decreases its permeability

Question 30

when is enamel soluble (whats the environment?) and travels in what direction

Answer 30

in acidic conditions and goes from the enamel surface to the DEJ

Question 31

what does fluoride ions do to enamel

Answer 31

these ions, during enamel formation or applied topically to its surface, DECREASES its solubility

Question 32

fluoride concentration decreases in what direction

Answer 32

from the surface to the DEJ

Question 33

fluoride can effect what properties of enamel

Answer 33

1. hardness of the apatite mineral 2. chemical reactivity 3. stability

Question 34

fluoride works to decrease/increase what things

Answer 34

1. DECREASE acid solubility 2. DECREASE rate of demineralization

Question 35

The density of enamel also decreases in what direction

Answer 35

from the surface to the DEJ

Question 36

enamel is a rigid surface that is both ____ and _____.

Answer 36

strong and brittle

Question 37

enamel's elastic modulus is

Answer 37

high

Question 38

enamel's compressive strength is

Answer 38

high

Question 39

enamel's tensile strength is

Answer 39

low

Question 40

dentin's elastic modulus is

Answer 40

low

Question 41

dentin's compressive strength is

Answer 41

high

Question 42

dentin's tensile strength is

Answer 42

high

Question 43

the junction of enamel and dentin is described as having what kind of appearance

Answer 43

scalloped with enamel projections into the dentin

Question 44

enamel rods that lack projection into dentin are classified as being

Answer 44

easy to fracture

Question 45

enamel rods should be

Answer 45

supported by dentin

Question 46

pulp and dentin are formed by what structure

Answer 46

the papilla of the tooth bud

Question 47

what are the 4 main functions of the pulp

Answer 47

1. formative/developmental 2. nutritive 3. sensory (protective) 4. defensive/reparative

Question 48

primary and secondary dentin is formed by what cells

Answer 48

odontoblast

Question 49

dentin nociceptors are unique because

Answer 49

various stimuli elicit pain ONLY as a response - not differentiating between heat, touch, pressure, or chemicals

Question 50

the pulp is lined on its periphery by

Answer 50

a cellular layer of odontoblast, the cell free zone, and the cell rich zone

Question 51

dentin is formed by what cellular process and by what cells

Answer 51

dentinogenesis odontoblast

Question 52

tomes fibers

Answer 52

odontoblastic cells that are apart of the pulp cavity and extend in the tubules of the mineralized dentin

Question 53

what happens/what are they called when odontoblasts cross into the enamel

Answer 53

enamel spindles

Question 54

dentin formation begins before or after enamel formation

Answer 54

immediately before. extracellular collagen is generated after they move away from ameloblast

Question 55

the most recent layer of dentin is always formed on what surface

Answer 55

pulpal surface

Question 56

new dentin is mineralized or unmineralized

Answer 56

unmineralized (pre-dentin)

Question 57

primary dentin is typically completed when

Answer 57

3 years after eruption

Question 58

where does secondary dentin form

Answer 58

on all internal aspects of the pulp cavity (thicker on the roof and floor of multi-rooted teeth)

Question 59

what is the composition of human dentin

Answer 59

50% inorganic material 30% organic material

Question 60

the organic material of dentin is composed of what

Answer 60

90% type I collagen 10% noncollagenous proteins

Question 61

the mineral content of dentin is less than____ but more than ______(s).

Answer 61

a. enamel b. cementum and bone

Question 62

the mineral content of dentin increases with

Answer 62

age

Question 63

dentin is distinguished from enamel during tooth prep by

Answer 63

1. color and opacity 2. reflectance 3. hardness 4. sound

Question 64

typically what color is dentin

Answer 64

yellow-white (black or brown when exposed to oral fluids)

Question 65

physical, thermal, chemical, bacterial, and traumatic stimuli are detected through what

Answer 65

fluid filled dentinal tubules (hydrodynamic theory)

Question 66

hydrodynamic theory suggests what

Answer 66

stimulus initiated rapid tubular fluid movement within the dentin tubules accounts for nerve depolarization

Question 67

which is more permeable - coronal or root dentin

Answer 67

coronal

Question 68

what odontoblast are first to respond to lesion formation

Answer 68

primary odontoblast

Question 69

a high concentration of inflammatory response mediators (cytokines and chemokines) may do what to primary odontoblast

Answer 69

signal death

Question 70

occlusion of the tubules lumen does what to the ability of light to pass through

Answer 70

increases

Question 71

tertiary dentin is what

Answer 71

reactionary

Question 72

tertiary dentin can be classified as

Answer 72

reactionary and reparative(structually different)

Question 73

overcontouring in tooth structure results in what

Answer 73

increased plaque retention that can lead to a chronic inflammatory state of the gingiva

Question 74

what is the function of proximal contacts

Answer 74

they promote normal healthy interdental papillae filling the interproximal space

Question 75

where is the proximal contact located

Answer 75

the incisal third of the approximating surfaces

Question 76

where is the 'col' located

Answer 76

lying beneath the contact area

Question 77

embrasures are covered by what type of epithelium

Answer 77

nonkeratinized

Question 78

which embrasure is typically bigger - lingual or facial

Answer 78

lingual

Question 79

what are dental caries

Answer 79

a preventable, chronic, and biofilm mediated disease modulated by diet

Question 80

caries is caused primarily by

Answer 80

imbalance of the oral flora (biofilm) due to the presence of fermentable dietary carbohydrates on the tooth surface over time

Question 81

the critical pH level for enamel is ____ and ____ for dentin

Answer 81

5.5 and 6.2

Question 82

a low pH does what to tooth structure

Answer 82

remove calcium and phosphate (demineralization)

Question 83

caries is a balance between

Answer 83

1. time 2. fermentable carbohydrates 3. host 4. cariogenic biofilm

Question 84

dental plaque

Answer 84

soft tenacious film accumulation on the surface of teeth