Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

DS1102 > Week 9 - Histology of teeth and Supporting Structures > Flashcards

Week 9 - Histology of teeth and Supporting Structures Flashcards

1
Q

What are the 3 mineralized tissues that teeth are composed of

A
  • enamel
  • dentine
  • cementum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where does enamel and dentine meet

A

Dentino-enamel junction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where does the cementum and dentin meet

A

cemento-dentinal junction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is enamel derived from

A

ectoderm
enamel organ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Does enamel have a regenerative capacity

A

no
produced once in lifetime

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In permanent teeth what is the thickness of enamel cusps

A

2.5mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

In deciduous teeth what is the thickness of enamel

A

1.3mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the physical properties of enamel

A
  • high abrasion resistance
  • extremely brittle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the chemical composition of enamel

A
  • Calcium hydroxyapatite 95-96% by weight
  • Water 2% by weight
  • organic matrix (enamel proteins) 1-2% by weight
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Is there enamel in demineralized sections

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are enamel rod/prisms

A
  • basic structural unit of enamel
  • comprised of millions of hydroxyapatite crystals packed together
  • each rod is 2.5mm long and 5-6 um thin
  • diameter of the rod correspond with the diameter of the cell which produce it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What direction do enamel rod/prisms run

A

run from dentino-enamel junction (DEJ) to surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the different enamel rod/prims patterns

A
  • pattern 1 (seen near the DEJ and Surface)
  • Pattern 2
  • Pattern 3 - has a head and tail region (predominant pattern, also called key hole pattern)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is interprismatic enamel

A

the enamel between prisms
- composition similar to prismatic enamel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why does the interprismatic enamel look different to prismatic enamel

A

angulation of crystals (40-60 degrees)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the border where the crystals of enamel rods and crystals of interprismatic enamel meet called

A

rod sheath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are hunter Schreger bands

A
  • an optical phenomena visible in tooth enamel
  • appearance is based on the way in which sectioned enamel rods reflect light
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What type of light helps you see hunter-schreger bands

A

reflected light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do hunter schreger dark bands correspond to

A

cross sectional rods (diazones)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What do hunter schreger light bands correspond to

A

longitudinally sectioned rods (parazones)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is gnarled enamel

A
  • prisms under cusp tips which appear more marked and irregular
  • this is an optical appearance of enamel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What causes gnarled enamel

A

the enamel rods directed vertically under a cusp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the clinical consideration of gnarled enamel

A

can cause drill problems and in some cases the dentist must replace the drill burr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is aprismatic/prismless enamel

A
  • the outer 20-100um of enamel of newly erupted deciduous teeth
  • highly mineralised
  • no prism boundaries
  • can also be seen in relation to DEJ
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What direction does aprismatic/prismless enamel run

A

prisms run parallel to the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why do aprismatic/prismless enamel form

A

due to the absence of tomes processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are incremental lines of enamel

A

microscopic growth lines found in tooth enamel that represents the rhythmic, incremental deposition of enamel during tooth development
- they form due to the changes in the secretory rhythm of enamel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the 2 types of incremental lines of enamel

A
  • cross striations
  • enamel striae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are cross striations (periodic bands)

A
  • lines that run at right angles to the long axes of the enamel prisms
  • seen at intervals of 4-6um across the rods in longitudinal sections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What rhythm does cross striations (periodic bands) represent

A

circadian rhythm
1 day/ 24 h cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are enamel striae (striae of retzius)

A
  • runs obliquely across prisms
  • appear as concentric rings in cross section
  • represents the successive positions of the enamel forming front
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What rhythm does enamel striae ( striae of retzius) represent

A

circaseptan (7 day) rhythm of enamel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What do exaggeration of striae reflect

A

systemic influence e.g. illness

34
Q

What are perikymata

A
  • incremental growth lines that appear on the surface of tooth enamel as a series of linear grooves
  • they run in a wavy manner forming perikymata grooves and perikymata ridges
35
Q

What are neonatal lines

A
  • type of striae of retzius
  • seen in both enamel and dentine primary teeth - but rarely seen in permanent dentition
  • the line represents the time of birth
36
Q

difference between neonatal lines and striae of retzius

A

neonatal lines are darker and larger than the rest of the striae of retzius

37
Q

What is the shape of the dentino enamel junction

A

scalloping pattern - with the concavities towards the enamel
- usually less mineralized

38
Q

What is the function of the shape of dentino enamel junction

A

provides stress relief during mastication

39
Q

What are enamel tufts

A
  • resembles tufts of grass
  • arise at the DEJ and runs in the inner third of the enamel
  • recur at approximately 100um intervals
  • considered as hypomineralized areas (less minerals)
40
Q

What direction do enamel tufts travel

A

same direction as the prisms

41
Q

What are enamel spindles

A
  • short, linear, dark, club shaped structures
  • most commonly seen beneath cusps
  • best seen in longitudinal sections
42
Q

Why do enamel spindles form

A

entrapped odontoblast processes between ameloblasts

43
Q

What are enamel lamellae

A
  • linear enamel defects the run the entire thickness of enamel
  • narrower, longer and less common than enamel tufts
  • best visualized in transverse sections
44
Q

Why might enamel lamellae form

A
  • incomplete maturation of group of prisms
  • cracks after eruption due to occlusal loading
45
Q

What changes in the environment is amelogenesis (formation of enamel) sensitive to

A
  • infection - turner tooth, Hutchinson’s teeth
  • radiation - enamel defects or complete absence of teeth
  • trauma - hypoplasia
  • fluoride - fluorosis
  • hereditary - amelogenesis imperfecta
46
Q

What does dentine form from

A
  • ectomesenchyme
  • produced by odontoblasts
47
Q

What are the physical properties of dentine

A
  • pale yellow in colour
  • harder than bone and cementum but softer than enamel
  • organic matrix and tubular structure provides greater compressive, tensile and flexural strength
  • permeable
48
Q

What is the chemical composition of dentine

A

70% inorganic - calcium hydroxyapatite
20% organic - collagen (90%) - type 1 and traces of 3 and 5
10% water by weight

49
Q

What are the structural components of dentine

A
  • odontoblast processes
  • dentinal tubules
  • peritubular dentine
  • intratubular dentine
50
Q

What are odontoblast processes

A

extensions of odontoblast cell bodies into dentinal tubules

51
Q

What are dentinal tubules

A
  • functional unit of dentine
  • extend radially from pulp to DEJ and CDJ
  • contains odontoblastic process, occasional nerve fibers and extracellular fluid
52
Q

What is the shape of dentinal tubules

A
  • they taper from pulpal (2.5um) to periphery (1um)

get smaller and less dense the closer to the DEJ

53
Q

What is the shape of dentinal tubules and what is it called

A
  • wavy shape
  • primary curvatures
54
Q

What is intertubular dentine

A
  • forms the bulk of the dentine
  • located between tubules (B)
  • represents primary secretion of odontoblasts
  • consist of type 1 collagen
  • fribers arranged roughly at right angles to tubules
55
Q

What is intratubular dentine (peritubular)

A
  • dentine immediately surrounding (A) the odontoblastic process
  • it is 5-12% more mineralized than intratubular dentine
56
Q

What is primary dentine

A
  • bulk of the dentine which is formed before eruption
57
Q

What are the 2 types of primary dentine

A
  • mantle dentine (first formed dentine, 5% less mineralized, collagen fibers are oriented perpendicular to DEJ)
  • circumpulpal dentine
58
Q

What is tome’s granular layer

A
  • hypo-mineralized areas
  • seen in radicular dentine near the CDJ
  • appears as dark (black) granular zone in ground sections
59
Q

Why does tome’s granular layer appear dark in colour and what causes it

A

spaces are filled with air and hence appear dark in ground sections
caused due to profuse looping dentinal tubules

60
Q

What is the hyaline layer

A
  • layer in between tome’s granular layer and cementum
  • 20um thick
  • bonds dentine to cementum
61
Q

What is pre-dentine

A
  • newly formed dentine without mineralization
  • it is the innermost layer (demineralized sections)
  • it its thicker in young teeth
62
Q

what is globular dentine

A

dark staining spherules which is in pre dentine(A)

63
Q

What is inter globular dentine

A

lighter staining dentin between globular dentin (B)
- in pre dentine

64
Q

What is secondary dentine

A
  • formed after the tooth eruption and root formation is over
  • growth is much slower than primary dentin and its deposition occurs mostly on the roof and floor of the coronal pulp chamber
65
Q

What is the function of secondary dentine forming mostly on the roof and floor of the coronal pulp chamber

A
  • protect the pulp chamber from exposure during cavity preparation or if the caries is advancing towards the pulp
  • as secondary dentine forms is decreases the volume of the pulp chamber
  • can cause the pulp chamber to be block making root canal treatment difficult
66
Q

What is the shape of secondary dentine

A

sharp bending of dentinal tubules

67
Q

What is tertiary dentine

A
  • dentine formed in response to various stimuli such as attrition, caries, restorative procedure
  • it is seen only in the region where the stimuli has occurred
  • rate of deposition is proportional to the degree of injury
  • its intention is to protect the pulp
68
Q

What is reactionary dentine/ regenerative dentine

A
  • dentine which is formed by the odontoblasts that have survived after the stimulus (caries, attrition or restorative procedure)
  • has irregular and fewer tubules
69
Q

What is reparative dentine

A
  • dentine formed by newly differentiated odontoblast like cells that replace the original odontoblasts that are destroyed by the stimulus
  • has irregular and fewer tubules plus more twisted tibules
  • normally the odontoblsts like cells move away from the dentine they form
70
Q

What is osteo dentine

A

the same as reparative dentine but the odontoblasts get entrapped into the dentine they form

71
Q

What is sclerotic dentine/transparent dentine

A
  • the filling up of calcified material in the dentinal tubules in response to external stimuli such as caries, attrition ore restorative procedures
  • this reduces the permeability of the dentine and hence protects of the dentine
  • highly mineralized in several tubules
72
Q

What does sclerotic/transparent dentine look like in transmitted light

A

light

73
Q

What does sclerotic/transparent dentine look like in reflected light

A

dark

74
Q

What are dead tracts

A

odontoblasts which are killed or retract due to injury
- empty tubules are filled with air in ground sections and hence appear black

75
Q

What do dead tracts look like in transmitted light

A

black

76
Q

What do dead tracts look like in reflected light

A

light

77
Q

What are the 2 types of incremental lines of dentine

A
  • short periodic markings
  • long period lines
78
Q

What are short periodic markings - incremental lines of dentine

A
  • may be seen as alternating light and dark bands (von ebner lines)
  • run at right angles to the tubules
79
Q

What are long period lines - incremental lines of dentine

A
  • Andresen lines
80
Q

What are clinical considerations of dentine (5)

A
  • highly sensitive tissue - when exposed lead to dentine sensitivity
  • permeable and hence pulpal irritation
  • secondary dentine formed as age advances
  • tertiary dentine deposition in response to severe injury
  • sclerotic dentine - deposited in response to an external stimulus such as slowly advancing caries

DS1102 (37 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions