Oral Biology Flashcards
(122 cards)
1
Q
In a specimen of mature human enamel with organic components visible, the enamel prism patterns can be visualised. What does the appearance of prisms indicate regarding the prismatic structure of enamel?
A
That the prisms run in different directions which gives enamel strength
2
Q
What is the significance of hunter-Schreger bands?
A
- They strengthen enamel and prevent cracks from occurring
- they also optimise resistance to processes such as attrition or abrasion
3
Q
What are the three potential origins of enamel lamellae?
A
- Damage ( e.g. mastication forces)
- Cracked from ground section processing
- Developmental defect
4
Q
Do enamel tufts follow the direction of enamel prisms?
A
Yes
5
Q
Are enamel spindles or tufts shorter?
A
Enamel spindles
6
Q
In which part of the crown are enamel spindles best developed?
A
At the cusps
7
Q
What is the relationship between enamel spindles and dentinal tubules?
A
Enamel spindles are short extensions of the dentinal tubules
8
Q
What inorganic substance is enamel mostly made up of?
A
Hydroxyapatite
9
Q
What percentage of hydroxyapatite makes up enamel by weight?
A
96%
10
Q
What is the basic unit of enamel?
A
Enamel prisms
11
Q
What are enamel prisms?
A
Repeated arrangements of hydroxyapatite crystals running from ADJ to outer junction
12
Q
What is the shape of an enamel prism?
A
Complex ‘key hole’ shape
13
Q
What two components comprise an enamel prism?
A
- Prism core
- Prism sheath
14
Q
What component of enamel prisms has more tightly packed hydroxyapatite crystals?
A
Prism core
15
Q
What component of enamel prisms has a micro-retentive surface where resin can lock into and mechanically bond?
A
Prism sheath
16
Q
Hydroxyapatite crystals are less tightly packed in prism sheath compared to prism core. True or false?
A
True
17
Q
Why do enamel prisms run an undulating course?
A
For strength. If enamel prims ran straight, there would be points of weakness and they would split easier.
18
Q
What is the term used to describe enamel prisms appearing twisted around each other at the cusps?
A
Gnarled enamel
19
Q
What structural component of enamel makes up the large majority of its thickness?
A
Enamel prisms
20
Q
Better bonding to sub-surface enamel will result in less retention. True or false?
A
False. Better bonding to sub-surface enamel = better retention.
21
Q
What substance may make acid etching more difficult and why?
A
Fluoride, as it strengthens the surface of the tooth.
22
Q
What are the ‘Striae of Retzius’ also known as?
A
Incremental growth lines
23
Q
What do incremental growth lines represent?
A
The different layers of enamel during crown formation
24
Q
How would Striae of Retzius be visualised on virtual microscope?
A
As periodic dark lines through enamel
25
Why do striae of Retzius appear as dark lines?
The dark lines may represent occasional metabolic disturbances of mineralisation
26
What are the shallow furrows, where striae of Retzius reach the surface of enamel known as?
Perikymata
27
What feature on the tooth surface might wear away if abrasive toothpaste is used?
Perikymata
28
What are the ridges between Perikymata called?
Imbrication lines of pickerill
29
What feature of enamel is referred to as hypomineralised?
Enamel tufts
30
Enamel tufts form due to…?
Incorrect enamel formation
31
Define hypomineralised
Condition that affects enamel. Occurs due to a disturbance during tooth development.
32
How do early enamel caries present?
As white spot lesions
33
How do you initially treat white spot lesions?
Apply high dose/concentration of fluoride in the aim to arrest caries process
34
Where does demineralisation of enamel start and why?
It starts in the prism sheaths of enamel prisms. This is because easier diffusion of acid into prism sheaths as the hydroxyapatite crystals are not as tightly packed as in the prism core.
35
What are the four histological zones of enamel caries?
1. Translucent zone
2. Dark zone
3. Body of lesion
4. Surface zone
36
Which zone of enamel caries is the advancing front?
Translucent zone
37
Which zone of enamel caries is the most porous and therefore looses the most enamel in caries process?
Body of lesion
38
Why should you not probe a carious lesion?
It could break the thin surface zone layer into the body of the lesion. This may create a cavity.
39
How does arrested caries appear histologically?
As a wide, well-developed dark zone
40
What factors may favour caries arrest?
- plaque control
- use of flouride
- altered diet
41
What are ground sections?
Cut hard tissues ( mineral present)
42
In a ground section, how would an area that is less mineralised ( hypomineralised) appear?
Dark
43
In a ground section, how will an area where light passes through easily appear in comparison to a hypomineralised area?
Lighter
44
In a ground section, areas that are more mineralised ( hypermineralised) will appear?
Light
45
What type of tissue is dentine?
Specialised connective tissue
46
What structural feature gives dentine strength?
Direction of collagen fibres that are parallel to ADJ
47
What cells produce dentine tubules?
Odontoblasts
48
What can be found within primary curvatures of dentinal tubules?
Secondary curvatures
49
What has more tubules per mm^2, surface or deep dentine?
Deep dentine (pre-dentine)
50
Is dentine vital?
Yes
51
Where are most of the nerves in dentine found?
At the pulp horns
52
What are the three classifications of dentine?
1. Developmental
2. Primary, Secondary and tertiary
3. Tubule
53
What are the two types of developmental dentine?
1. Mantle dentine
2. Circumpulpal dentine
54
What is the first formed dentine called and where is it found?
Mantle dentine, adjacent to enamel.
55
What type of dentine lies between the enamel and pulp chamber?
Primary dentine
56
What type of dentine is deposited in the pulp chamber after the formation of primary dentin is complete
Secondary dentine
57
What type of dentine forms as a reaction to stimulus such as caries, wear and fractures?
Tertiary dentine
58
What are the two types of tertiary dentine?
- reactionary
- reparative
59
What type of tertiary dentine uses existing odontoblasts?
Reactionary
60
Where would you find peri-tubular/ intra-tubular dentine? And is it mineralised or not?
Around the tubule, yes its mineralised.
61
Where would you find inter-tubular dentine?
Between tubules
62
What are line features of dentine?
- incremental lines of von ebner
- contour lines of Owen
63
what are zone features of dentine?
- interglobular dentine
- granular layer of tomes
64
What feature of dentin shows the position of odontoblast a at different times during development?
Incremental lines of von ebner
65
What feature of dentine is a coincidence of secondary curvatures?
Contour lines of Owen
66
What feature of dentine forms as a result of failure of calcospherites to fuse?
Interglobular dentine
67
What is the layer on the subsurface toot of dentine that has a granular appearance?
Granular layer of tomes
68
The process which blocks of dentinal tubules, in turn, slowing down the advance of caries, is known as?
Sclerosis
69
What feature of dentine forms as a result of odontoblast overcrowding, causing odontoblast death?
Dead tracts
70
what type of dentine has a fracture risk for extraction and why?
Translucent sclerotic dentine, because it is less flexible at the roots
71
What are the three zones of a carious lesion?
1. Advancing front
2. Zone of bacterial penetration
3. Zone of destruction
72
What occurs at the advancing front of carious lesion?
Acid damage
73
What occurs at zone of bacterial penetration of a carious lesion?
Bacterial invasion
74
What occurs at the zone of destruction of carious lesions?
Breakdown of organic matrix
75
What are the principle periodontal ligament fibres?
- transeptal fibres
- bundles of circumferential fibres
76
In between teeth, what three cells are found in the crestal bone?
Osteoclasts in their lacunae
Osteoblasts
Osteoclasts
77
Which cell is trapped in the organic matrix of bone?
Osteocytes in their lacunae
78
What cell associated with bone is considered alive?
Osteocytes in their lacunae
79
what bone associated cell deal with new bone resorption?
Osteoblasts
80
What bone associated cell deals with aged bone resorption?
Osteoclasts
81
What is the purpose of osteoclasts?
They eliminate weakened or damaged bone tissue
82
What area of the tooth cementum is the thickest?
Apical cementum
83
What areas of the tooth cementum are the thinnest?
Cervical and inter-radicular cementum
84
Which is laid down the quickest? Cellular or acellular cementum.
Cellular
85
The porous nature of what bone is utilised in infiltration and intraligamentary LA?
The porous nature of the buccal bone
86
What direction to the cannaliculi in cementum point and why?
They point towards the PDL for nutrition
87
what is hyper-cementosis?
Excessive deposition of cementum
88
What are the three types of mucosa found in the oral cavity?
- masticatory mucosa
- lining mucosa
- specialised mucosa
89
What do all epithelial cells contain?
Filaments and desmosomes
90
What are the four layers (from superficial to deep) of non-keratinised lining mucosa?
- epithelium
- lamina propria
- submucosa
- bone/muscle
91
What glands are found in lining submucosa?
Salivary glands
92
What are the four epithelial layers of non-keratinised lining mucosa? ( from superficial to deep)
- superficial layer
- intermediate layer
- prickle cell layer
- basal cell layer
93
What is another term for non-keratinocyte?
Clear cells
94
In what layer are clear cells normally found?
Basal layer:
- basal clear cells
- supra-basal clear cells
95
What are the four layers (from superficial to deep) of keratinised masticatory mucosa?
Epithelium
Lamina propria
periosteum
Bone
96
What are the four epithelial layers of keratinised masticatory mucosa? ( from superficial to deep)
Keratinised
Granular
Prickle cell
Basal cell
97
What do ‘clear cells’ lack?
Filaments and desmosomes
98
What two types of clear cells only exist in the basal cell layer?
Merkle cells and melanocytes
99
What two types of clear cells exist in the supra-basal layer?
Inflammatory cells and langerhan’s cells
100
what are the three layers of specialised mucosa? ( superficial to deep)
Epithelium
Lamina propria
Muscle
101
What are the four epithelial papillae found in specialised mucosa?
- circumvallate
- foliate
- filiform
- fungiform
102
What are serous glands of von ebner?
Accessory minor salivary glands
103
What type of mucosa is flexible and slightly permeable?
Lining mucosa
104
What type of mucosa is inflexible and impermeable?
Masticatory mucosa
105
What lining material has a potential therapeutic effect on the pulp and why?
Dycal, as it may stimulate tertiary dentine formation
106
What four cells are contained in the pulp?
- odontoblasts
- fibroblasts
- stem cells
- defence cells
107
How far do the odontoblast processes extend into dentine?
1/3 of the way
108
Where does the blood supply of the pulp terminate?
In the rich sub-odontoblastic capillary plexus
109
How does pulpal death occur?
Due to stasis of blood in vessels as a result of competing pressures in the capillary beds within the tissues
110
What types of nerve supply does the pulp have?
Mainly sensory (afferent), also efferent ( post-ganglionic sympathetic)
111
What is the predominant type of nerve fibre in te pulp?
Unmyelinated C fibres
112
What pulpal zone is the plexus of Raschkow classically in?
The cell free zone
113
What is the negative impact of pulp stones?
Can causes issues when trying to access pulp with instruments
114
What is the pulpal response to formation of reactionary tertiary dentine?
-TGF beta is released from carious/demineralised tissue
- increase in odontoblast dentine formation
115
What is the pulpal response to exposure?
- Ca(OH)2 and MTA cement induces a dentine bridge
116
What is a dentine bridge?
A new reaction tissue that preserves pulp vitality and protects it from abnormal and continuous physical stimuli
117
What type of epithelium is found in oral mucosa?
Stratified squamous epithelium
118
What cell is predominant in connective tissue?
Fibroblasts
119
What is the rare condition characterised by slowly progressive overgrowth of the gingiva?
Hereditary gingival firbomatosis
120
What are the primary lymphoid organs?
Bone marrow and thymus
121
What are the secondary lymphoid organs?
Spleen and lymph nodes/nodules
122
What does MALT stand for?
Mucosa-associated lymphatic tissue
