final Flashcards
1
Q
% volume composition of enamel
A
- 1-2% protein
- 4-8% water
- 90-95% inorganic (Hydroxyapatite = HA)
2
Q
enamel organization
A
- rods or prism that run from DEJ to surface
- smaller in diameter at DEJ and almost double at the surface
3
Q
what tissue is enamel derived from?
A
epithelial
4
Q
what cells do enamel arise from
A
-ameloblasts; extinct after deposition
5
Q
what tissue is the dentin/pulp complex derived from?
A
mesenchyme
6
Q
what cells do dentin/pulp arise from?
A
odontoblasts; these odontoblasts remain in the pulp
7
Q
each enamel rod/crystallite is surrounded by an…?
A
organic sheath
8
Q
the long axis of the crystals making up the rods are ____ to rod direction
A
parallel
9
Q
what is gnarled enamel and what is its clinical significance?
A
-gnarled enamel is entwined enamel rods, and it occurs mostly at cervical and incisal/occlusal areas. It’s purpose is to resist fracture incidence
10
Q
describe the characteristics of enamel in parallel to the rods
A
-hard, brittle, and stiff
11
Q
describe enamel’s tensile strength
A
- low tensile strength
- rods easily cleaved/separated along the perpendicular direction
12
Q
enamel fracture lines are….
A
interprismatic
13
Q
enamel is anisotropic or isotropic?
A
anisotropic (not the same in all directions)
14
Q
is composite anisotropic or isotropic
A
isotropic (same in all directions)
15
Q
dentin volume composition
A
- 25% water
- 25% collagen (protein)
- 50% HA
16
Q
dentin weight composition
A
- 75% HA
- 20% collagen
- 5% water
17
Q
what happens to pulp with age?
A
-it shrinks, making for less sensitive teeth
18
Q
which cells line the pulpal wall?
A
-odontoblasts
19
Q
which is more dense… intertubular or peritubular dentin?
A
-peritubular; this is found surrounding the individual tubules where the intertubular dentin resides between tubules
20
Q
what are the functions of dentin tubules?
A
- allow fluid movement and ion transport
- remineralization
- pain perception
- apposition of peritubular dentin
21
Q
how do tubules in superficial dentin compare to those in deeper dentin?
A
smaller and more spread out
22
Q
is dentin uniformly mineralized?
A
No, peritubular dentin more mineralized than intertubular dentin
23
Q
-size of HA crystals in dentin
A
-200-1000 Angstroms long, 30 A diameter
24
Q
dentin types
A
- predentin - unmineralized zone of dentin immediately adjacent to odontoblast cell bodies
- primary dentin- closest to DEJ
- secondary dentin - closest to pulp
25
4 functions of pulp
1. Formative or developmental
2. Nutritive
3. Sensory or protective
4. Defensive or reparative
26
which of the tooth components has the highest fluoride content
cementum
27
cementum weight comp
- 5-10% mineral
- 45-50% HA
- 50-55% organic material and water (primarily collagen)
28
cells that form cementum
cementoblasts
29
tissue that forms cementum
undifferentiated mesenchymal cells
30
can cementum undergo self-repair
yes, to a limited degree
31
what is dental caries
Multifactorial, transmissible, infectious oral disease caused primarily by the complex interaction of cariogenic oral flora (biofilm) with fermentable carbohydrates on the tooth surface over time
32
caries result from an intersection of which 3 factors in the TRADITIONAL VIEW
1. bacteria
2. carbohydrates
3. tooth structure
33
In the MODIFIED VIEW, caries result from an intersection of which 4 factors
1. Time
2. Host
3. Fermentable carbs
4. Cariogenic biofilm
34
which type of caries tends to come first: facial smooth surface lesions or occlusal/interproximal smooth surface lesions?
occlusal/interproximal
35
what is the critical pH for enamel (HA)? For enamel (Hydroxyfluorapitite)? For dentin?
5.5, 4.5, 6.2
36
briefly explain what initiates demineralization
- cariogenic bacteria metabolize refined carbs for energy, producing organic acid by-products
- this lowers the pH below the critical level
- low pH drives calcium and phosphate from the tooth to the biofilm in an attempt to reach equilibrium
37
The Caries balance: pathological factors (demineralization)
- acid producing bacteria
- sub-normal saliva flow
- frequent eating/drinking of fermentable carbs
- poor oral hygiene
38
what makes saliva important to the demineralization/mineralization balance?
it is supersaturated with calcium, phophate
39
what is an example from the slides of a species of bacteria associated with low pH
lactobacilli
40
As Dr. Sharples stated multiple times, what is key to caries management?
Understanding the balance between demineralization and remineralization
41
Caries management based on the Medical Model:
1. Treatment, symptomatic?
2. Treatment, therapeutic?
3. Post-treatment assessment, symptomatic?
4. Post-treatment, therapeutic?
1. restoration of cavitated lesions
2. improvement of host resistance by... biofilm control, elevating biofilm pH, and enhancing remineralization
3. examination for new lesions
4. re-eval of etiological conditions and primary/secondary risk factors
42
what is primary caries
a caries lesion not adjacent to an existing restoration or crown
43
what is secondary caries?
a caries lesion adjacent to an existing restoration, crown, or sealant
-aka CARS (Caries Adjacent to Restorations and Sealant)
44
Residual caries are
carious tissue that was not completely excavated prior to placing restoration
45
What are also known as "white spot" lesions?
non-cavitated caries lesion
46
What is rampant caries
term used to describe the extensive and multiple cavitated and active caries lesions in the same person
47
3 "slang" terms for rampant caries
1. baby bottle caries
2. Radiation therapy caries
3. Meth-mouth caries
48
What is biofilm mostly composed of
1. bacteria
2. their by-products
3. ECM
4. water
49
what is the first step in bacterial plaque formation?
Acquired pellicle forms within 30 mins - hour
50
what is the composition of the acquired pellicle
- salivary proteins
| - cell free?
51
what are the roles of the pellicle
- protection (immunoglobulins)
- reduces friction
- remineralization
52
the surface of non-cavitated enamel lesions has what kind of appearance?
punched-out
53
Plaque near gingival sulcus has less ___ forms of bacteria and more ____ bacteria
coccal; filamentous
54
At how long is plaque almost entirely composed of filamentous bacteria
3 weeks
55
In which two HEALTHY oral habitats are the oxidation-reduction potentials negative
- teeth (non-carious)
| - gingival crevice
56
in which two oral habitats are the oxidation-reduction potentials positive
- tongue
| - mucosa
57
what is the predominant species within enamel caries
S. mutans
58
what are the predominant species in dentin caries
S. mutans
| lactobacillus
59
what is the predominant species in root caries
actinomyces
60
what are the 5 tooth habitats favorable for harboring pathogenic biofilm
1. pits and fissures
2. smooth surfaces immediately gingival to proximal contacts
3. gingival 3rd of the facial and lingual surfaces of the clinical crown
4. root surfaces near the cervical line
5. subgingival areas
61
on an X-ray, are caries recognizable as radiolucencies or radiopacities
radiolucencies
62
During periods of unrestricted growth, which two surfaces (fac, mes, ling, dist) become part of a continuous ring of plaque around the teeth?
mesial and facial
63
Why are caries on the root so alarming?
1. rapid progression
2. often asymptomatic
3. closer to the pulp
4. more difficult to restore
64
What is xerostomia?
production of little to no saliva, leading to dry mouth
65
what are the salivary protective mechanisms (4)
1. bacterial clearance
2. direct antibacterial activity
3. buffers
4. remineralization
66
the buffering capacity of saliva is determined primarily by the concentration of what ion?
bicarbonate
67
which molecules in saliva contribute to increasing biofilm pH
urea and sialin
| -hydrolysis of either of these releases ammonia, which is basic, causing pH to increase
68
which substance in saliva prevents the excessive deposition of phosphate and calcium ions on the teeth
statherin
69
This gram-positive bacteria is likely found in the pits and fissures of newly erupted teeth
S. Sanguis
70
demineralization in pits and fissures follows which direction
the direction of the enamel rods; spreads laterally as it approaches the DEJ
71
Describe the beginning of smooth surface caries
- begins as a broad area of origin
- conical, pointed extension to the DEJ
- parallel to the long axis of the rods
72
The time for progression of non-cavitated to cavitated lesions is how long
18 months plus-or-minus 6 months
73
After the tooth has erupted, what is the peak rate for formation of new lesions
3 years
74
How quickly can radiation-induced xerostemia lead to clinical caries development?
3 months
75
what is a whie spot lesion
noncavitated enamel caries lesion
76
the presence of trace amounts of what ions greatly enhances the precipitation of calcium and phosphate during remineralization?
Fluoride
77
how can we clinically observe remineralized lesions?
They will show as black or brown spots, the color presumably caused by trapped organic debris or metal ions within the enamel
78
What in the dentin provides a pathway for the ingress of bacteria and egress of minerals
dentin tubules
79
what area in the tooth has the least resistance to caries attack and allows for the lateral spreading when caries has penetrated the enamel
the DEJ
80
in long-term, low-level acid demineralization, is direct exposure of the pulp tissue to microorganisms a prerequisite for inflammatory response?
No; even when limited to the enamel, the pulp has shown to take inflammatory action
81
what may be the most important limiting factor to pulpal responses?
the pulpal blood supply
82
Caries advancement in dentin proceeds thru 3 changes:
1. weak organic acids demineralize dentin
2. the organic material of dentin, particularly collagen, degenerates and dissolves
3. the loss of structural integrity is followed by invasion of bacteria
83
what are the 3 zones of dentin caries?
1. normal dentin
2. affected dentin
3. infected dentin
84
what is also known as inner carious dentin?
affected dentin, zone 2
85
is collagen cross-linking still intact in zone 2
yes, can serve as template for remineralization of intertubular dentin
86
what are the 3 subzones of affected dentin
1. subtransparent
2. transparent
3. turbid
87
The necessary compliance and behavioral changes that can decrease risk for caries patients are predictable at the ___ level but not the ____ level
population; individual
88
A dental examine determines ___ instead of ____
risk indicators; risk factors
89
Is visible plaque a risk INDICATOR
No, it's a risk FACTOR
90
3 preventative treatment measures for caries
1. limiting pathogen growth and altering metabolism
2. increasing the resistance of the tooth structure to demineralization
3. increasing biofilm pH
91
which term refers to an operating procedure in which multiple teeth with acute threatening caries are treated quickly
caries control
92
large carious lesions with healthy pulpal and periapical tissues should be managed how?
partial caries excavationand indirect pulp capping
93
4 primary strategies for the prevention of root caries
1. try to improve salivary flow rates and increase buffering capacity
2. reduce number of cariogenic bacteria
3. reduce quantity of exposure to refined carbs
4. attempt to remineralize noncavitated lesions and prevent new lesions
