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PER 1001 > Biofilm & Plaque Formation Pt. 2 > Flashcards

Biofilm & Plaque Formation Pt. 2 Flashcards

1
Q

When can colonizing bacteria be detected?

A

detected within 3 minutes after the introduction of sterile enamel into the mouth.

Immediately after introduction to oral cavity

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2
Q

When bacterial cells are in loose contact with the pellicle, what is important?

A

The proteins and carbohydrates that are exposed become important with this interaction

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3
Q

The specific interactions between microbial cell surface “adhesin” molecules and receptors in the salivary pellicle determine what?

A

whether a bacterial cell will remain associated with the surface.

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4
Q

What organims are the most abundant bacteria in biofilms on tooth enamel shortly after cleanings and why?

A

Only the relatively small proportion of oral bacteria possess adhesins that interact with receptors in the host pellicle

Adhesion ability of bacteria makes them specific to person

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5
Q

After the first 4-8 hours what genus of bacteria dominates in attachement?

A

genus Streptococcus
accounting for >20% of bacteria present.

+ obligate aerobes(nesseria) & faculative aerobes (actinomycyes & veillo

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6
Q

What 5 species are the primary colonizes of tooth surfaces

A
  1. Streptococcus spp.
  2. Haemophilus spp.
  3. Neisseria spp.
  4. Actinomyces spp.
  5. Veillonella spp.

Seek Help Not Attention it’s Vain

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7
Q

What do primary colonizers do for other bacteria?

A

Coadhesion
* provide new binding sites for adhesion by other oral bacteria.
* Metabolic ativity can inflience abolity of other bacteria to survive in dental plaque biofilm

eventually develop into biofil

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8
Q

Explain a metabolic way that primary colonizers of dental plaque help growth of obligate anerobes

A

byremoving oxygen, the primary colonizers provide conditions of low oxygen tension that permit the survival and growth of obligate anaerobes

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9
Q

What are the 3 phases of attachment of bacteria

A
  1. Transport to surface
  2. Inital Adhesion
  3. Strong attachment
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10
Q

Explain the 1st phase of bacterial attachment

A

transport of bacteria to the tooth surface
* Saliva flow and mechanical contact btwn oral soft tissue allow for primary colonizng bactera to contact teeth

most bacteria is not motile

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11
Q

Explain the 2nd phase of bacterial attachment

A

an initial reversible adhesion of the bacterium
* Bacteria comes in close contact w/surface 50nm
* Long and short range foces occur (van der wall attractive, and electorstatic repulsive)
* Van der wall result in net attraction of bacteral cell 10nm away from surface
* Stronger binding occurs via bacterial adhesions and receptors in the salivary pellice.

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12
Q

How many ligand-receptor interactions are required to attain essentially irreversible binding of a bacterial cell to the pellicle?

A

10-50 ligand receptor interactions

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13
Q

Explain the 3rd phase of bacterial attachment

A

firm anchorage between the bacterium and the surface is established.
* rough surface= bacterai more protected from forces that could displace them.

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14
Q

What is a specific quality of Capnocytophaga spp?

A

They prefer areas of high CO2 levels, found a little deeper.

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15
Q

Explain

A

primary colonizers
* Blue= gram + facultative anerobes
* Red= gram - anerobes

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16
Q

Secondary Colonnizers

A

**Gram - Anerobes / Facultative anerobes
Rods & spirochetes . **

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17
Q

Explain the relationship of S. gordonii and A. Oris

A

They coagreggate
* A .oris will only grow if you have S. gordoni with it. Bind to each other and aggregate

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18
Q

What complexes do primary colonizers come from?

A
  • Yellow (strep. spp)
  • Purple (a. odontolyticus
  • Blue (actinomyces spp)
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19
Q

What complexes do secondary colonizers come from?

A

Green, Orange, Red comeplexes

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20
Q

What are 3 spp. in green complex?

A
  1. Eikenella corroden
  2. Capnocytophaga spp.
  3. A. actinomycetemcomitans serotype a
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21
Q

What are 3 spp. in orange complex?

A
  1. Fusobacterium
  2. Prevotella
  3. Campylobacter spp.
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22
Q

what 2 complexes nclude species recognized as pathogens in periodontal and nonperiodontal infections.

A

Green and Orange complexes

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23
Q

3 Members of Red complex?

A
  1. T denticola
  2. P gingivalis
  3. T forsynthia
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24
Q

Explain this

A

Start with a plaque free subject with clinically non-inflamed ginigva
1. Plaque will slowly develope if all mechnical palque control is stopped
2. First few days= mostly gram + cocci & rods
3. Later on= shift toward gram - rods & filaments
4. Finally= Gram - spirochetes
5. Within few days mild ginigivities ensues
6. Once oral hygiene plaque control is restablihsed plaque composition returns to intila gram + situation and gingivitis dissapears

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25
Where does dental plaque growth start?
**areas that are protected from shear forces** such as the * gingival margin * interdental space * along grooves, cracks, pits, and fissures.
26
Explain biofilm growth and planktonic growth and how it affects antimicrobial resistance
Planktonic grow suspended in liquid enviroment, while biofilm bacteria grow while attached to somthing. **The resistance of bacteria to antimicrobial agents is dramatically increased in the biofilm. 1000x more**
27
What are some facors that affect resistance of bacteria to antibiotics?
* Nutritional staus * Growth rate * temp * pH * Prior exposure to antimicrobial
28
What is an important mechanism of resitance of of biofilm bacteria?
**slow growth rate** * makes them less susceptible to many but not all antibiotics.
29
Why is it hard for antibiotics to penetrate biofilms
**Biofilm can act as an ion-exchange resin** that removes the strongly charged/ chemically reactive agents of the antimicrobial= fail to reach deep zones.
30
What can happen to antimicrobial extracellular enzymes like * β-lactamases * formaldehyde lyase * formaldehyde dehydrogenase when they encounter a biofilm?
**become trapped and concentrated in the extracellular matrix,** and as such inactivate some antibiotics | **positively charged hydrophilic antibiotics**
31
What antibiotic is resitant to being traped in the extracellular matrix of biofilms and why?
**Macrolides** * Positivley charged **hydrophobic** * Uaffected by process!
32
Explain Supperresitant bacteria
These cells have **multidrug resistance pumps** that can **extrude antimicrobial agents from the cell.**
33
What do superessitant bacteria pumps specifcially do and target?
**place the antibiotics outside of the outer membrane** * all for resitance against antibiotics that targer cell wall synthesis
34
How does antibiotic resistance spread through a biofilm?
intercellular exchange of DNA
35
consists of **mineralized bacterial plaque** that forms on the surfaces of natural teeth and dental prostheses
Calculus | **can be seen on x-rays**
36
is located **coronal to the gingival margin** and therefore is **visible** in the oral cavity
**Supra**gingival Calculus
37
Explain color, consitancy, removal of **supra**gingival calculus
* Whute or whitish yellow * Hard, clay like consistency * Easily detachable from tooth surface BUT easily recurring. * Can be localized to a tooth or generalized
38
Where is **supra**gingival plaque most commonly reoccuring?
the lingual area of the mandibular incisors
39
What influences the color of **supra**gingival calculus?
Color influced with substances like tobacco and food pigments.
40
What is the fundamental cornerstone to tx of chronic periodontitis?
Mechanical removal of **subgingival** plaque and calculus
41
located**below the crest of the marginal gingiva** and therefore is not visible on routine clinical examination
**Sub**gingival plaque
42
Explain color, consitancy, removal of **sub**gingival calculus
* Location and extent evalulated by instriment * Hard dense * Dark brow/ greenish * Firmly attached to tooth
43
Explain relationship of sub and supra gingival calulus and they occurance
generally occur together, but one may be present without the other.
44
What happens to the classification of subgingival calculus when **gingival tissue receads**?
subgingival calculus becomes **exposed**and is therefore reclassified **as supragingival** Thus Supra calculus can be composed of both the initial supra calculus and previous sub calculus
45
What can be noted after **removal** of subgingival palque and calculus?
* Reduction in gingival inflammation + probing depth * Gain in clinical attachment of gingiva
46
**radiopaque projections that protrude into the interdental spaces** are what?
Highly calcified interproximal calculus deposites | *note that detection levels are inconsitant**
47
Location of calculus does not indicate the what? and why?
does not indicate the*bottom of the periodontal pocket* because * most **apical plaque** is not **sufficiently calcified to be visible on radiographs**
48
Explain general compostion of calculus
Inorganic= 70-90% Organic= the rest
49
What makes up the major **inorganic component of calculus?**
* Calcium phosphate (7.6%) * Calcium carbonate * magnesium phosphate * carbon dioxide + other trace element | Similar to that of other calcified tissues in the body
50
What hard tissue in the body has the most inorganic content?
Calculus! 70-90%
51
What makes up the major **organic component of calculus?**
mixture of * protein–polysaccharide complexes * desquamated epithelial cells * Leukocytes * various types of microorganisms. Carbs, Salivary protiens, lipids | **all present in salivary glycoprotien
52
How does attachment manner of calculus affect ?
affect the **relative ease or difficulty** encountered during its **removal**
53
What are the 4 modes of calculus attachment?
1. Supra 2. Sub 3. Attachment by means of **organic pellice** 4. **Mechanical locking** on to surface irregularties like caries lesion or reorbtion lacunae
54
What does this picture depict?
Calculus attached to the pellicel on the enamel surface and the cementum.
55
What does picture depict?
Calculus attached to enamel surface, just coronal to CEJ
56
How is soft plaque harden into calculus?How long to calcify? Does this always occur?
* Hardened by the **precipitation of mineral salts**, which usually starts between the **1st and 14th days of plaque formation** * Calcification starts within 4-8 hrs * 50% minerlaized by 2 days, 60-90% in 12 days * BUT all plaque does not undergo calcification * microbes not always essential in formation
57
**Plaque that does not develop into calculus** reaches a **plateau of maximal mineral content** within how many days?
2 days
58
Does calculus contribute directly to gingival inflamation?
**NO** It **retains dental plaque** which contributes to gingival inflammation. Open room by tissue= BAD
59
What is the **primary source of mineralization** for **supra**gingival calculus
Saliva!
60
What is the **primary source of mineralization** for **sub**gingival calculus?
**gingival crevicular fluid** (GFC, transudate; albumin) furnishes the minerals for **subgingival calculus**
61
Compare calcium content in calculus to that of saliva
Calcium in calculus is 2-20x higher than saliva
62
What mineral is **more critical in plaque mineralization** and why?
**Phosphorous!** Early plaque of **heavy calculus formers** contains more calcium, **3x more phosphorus**, and less potassium **than that of noncalculus formers**,
63
What does calcification of dental plaque entail?
* **Binding of calcium ions** to carb-protien complex of organic matrix in plaque * **precepitation** of cyrstilline calcium phosphate salts
64
Explain trend of crystalization location in calculus formation
* 1st in intracellular matirx + bacterial surface * then within bacteria
65
The calcification of **supragingival plaque** and the **attached component of subgingival plaque** begins where?
along the inner surface**adjacent to the tooth structure. **
66
What do foci of calcification do?
increase in **size and coalesce** to form **solid masses of calculus**
67
What is required for intital mineralizationt to occur?
1. Calcium-phosphate supersaturation 2. membran asc. components 3. regulation of nuclear inhibitors
68
What can sometimes accompaany calcification?
* **alterations** in the bacterial content * **staining** qualities of the plaque.
69
As calcification progesses what is the trend in bacteria content
* number of **filamentous bacteria increases** * foci of calcification change from basophilic to **eosinophilic** (more acidic)
70
groups that exhibit a **positive periodic acid–Schiff reaction** show what?
a reduction in the staining intensity
71
What is the 1st theoretical mechanism by which plaque becomes mineralized
1. Mineral precipitation results from a **local rise in the degree of saturation of calcium and phosphate ions**
72
What factors can elevate the pH of saliva
* **Loss of CO2** * **Formation of amonioa** by dental plaque bactera though protein breakdown during stagnation of saliva
73
Explain the relationship of collodial protiens and calcium phosphate
* Normally **Colloidal proteins in saliva bind calcium and phosphate ions** and maintain a **supersaturated solution** * When **saliva stagnates, collodies settle,** supersaturated state no longer maintained= **precipitation of calcium phosphate salt**.
74
Enzymes like phosphatase and esterases released by dental plaque, epithelial cells, or bacteria can also do what?
precipitates calcium phosphate by hydrolyzing organic phosphates in saliva.
75
What is the **2nd theoretical mechanism** by which plaque becomes mineralized?
**heterogeneous nucleation** Seeding agents induce small foci of calcification that enlarge and coalesce to form a **calcified mass**. The **carbohydrate–protein complexes** may initiate calcification by removing calcium from the saliva (chelation) and binding with it to **form nuclei** that induce the subsequent deposition of minerals.
76
# Role of Microorganisms in the Mineralization of Calculus Explain locational trend in minerlaization
* Start extracellularly *both gram +/-* * But may also start intracelllarly * Filamentous organims can form intracellular apatite crystals * Mineralization spreads until matrix and bacteria are calcified **Bacterial plaque may actively participate in the mineralization of calculus by forming phosphatases, which change the pH of the plaque and induce mineralization **
77
an accumulation of microorganisms, desquamated epithelial cells, leukocytes, and a mixture of salivary proteins and lipids, with few or no food particles;
Materia Alba * No internal plattern * Yelow-grayish soft white sticky * less adhearent han dentlal plawur
78
what is The irritating effect of materia alba on the gingiva is caused by what?
bacteria and their products
79
Most **food debris** is ____ and cleared from the oral cavity by **salivary flow** and the **mechanical action of the tongue, cheeks, and lips.**
rapidly liquefied by bacterial enzymes
80
Compare clearance of aqueous vs sticky substnaes in mouth
Aqueous cleared= 15 min Sticky= more than 1hr to clear
81
Pigmented deposits on the tooth surface are called?
Dental Stains
82
Do stains cause inflammation?
NO! they are an aesthetic problem
83
The use of tobacco products coffee, tea, certain mouthrinses, and pigments in foods can contribute to what?
Stain formation
84
Explain how a rise pH can result in mineral precipitation of calcium and phosphate ions
Arise in saliva, pH causes precipitation of calcium phosphate, salt by lowering the precipitation constant

PER 1001 (9 decks)

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