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PER > PER02-2005 Plaque & calculus > Flashcards

PER02-2005 Plaque & calculus Flashcards

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1
Q

What are the two types of oral bacteria?

A

Planktonic and sessile

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2
Q

What is planktonic bacteria?

A

Bacteria that floats in the saliva

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3
Q

What is sessile bacteria?

A

Sessile bacteria is attached to surfaces of the mouth and grows in the biofilm

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4
Q

What is dental plaque?

A

Dental plaque is a complex microbial community that develops on the tooth surface, embedded in a matrix of polymers of bacterial and salivary origin

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5
Q

What is plaque that becomes calcified referred to as?

A

Calculus or tartar

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6
Q

What are the 4 stages of plaque formation?

A

Acquired pellicle formation
Adhesion of pioneer microbial colonisers to the pellicle
Coaggregation of microbial species present in the plaque
Maturation of plaque

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7
Q

How does the acquired pellicle form?

A

An acquired pellicle forms a few minutes after brushing on the clean tooth surface
It is a layer of saliva composed of mainly glycoproteins, phosphoproteins and lipids

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8
Q

What feature of the enamel surface makes it easier for molecules in the saliva to adhere to it?

A

Enamel surface is negatively charged due to negative phosphate groups

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9
Q

What forces attract bacteria to the acquired pellicle?

A

Van der Waals bring bacteria closer to the surface however this adhesion is reversible and can be washed away

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10
Q

Which part of the tooth do bacteria attach to?

A

Acquired pellicle only to the clean enamel surface

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11
Q

How do pioneer microbial colonisers produce extracellular polysaccharides?

A

Pioneer microbial colonisers have different receptors that can attach to the surface of the acquired pellicle
This adhesion is much tighter and specific and resistant to removal by saliva and chewing
The pioneer microbial colonisers begin to divide and produce extracellular polysaccharides

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12
Q

How do bacteria store carbohydrates?

A

Oral bacteria survive from nutrients, because we dont constantly eat EPS they are used by bacteria to store carbohydrates

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13
Q

How do pioneer species change to environment?

A

Pioneer species begin to ferment glucose and other metabolites
Consume O2
Produce CO2
So succession occurs

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14
Q

Which species acts as a bridging species between early and later colonisers in coaggregation?

A

Fusobacterium nucleatum

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15
Q

How does fusobacterium nucleatum act as a bridging species?

A

Once fusobacterium nucleatum has attached to the early species, late colonisers then attach to the fusobacterium nucleatum

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16
Q

What occurs during maturation of plaque?

A

The growth rate slows down, however there is a continuous production of EPS, which leads to structural integrity, tolerance to environmental factors and microbial

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17
Q

What forces limit the further expansion of the dental biofilm?

A

Forces of mastication

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18
Q

What is material alba?

A

The soft accumulation of bacteria, tissue cells and food particles that lack the organised structure of dental plaque (no EPS)
Material alba is loosely attached to the tooth surface and can be displaced by rinsing, unlike dental plaque

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19
Q

What is calculus?

A

Mineralised plaque with calcium phosphate crystals

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20
Q

Why is calculus not causative of periodontitis?

A

It is covered by a layer of biofilm

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21
Q

How does calculus form?

A

The plaque is mineralised
There is a precipitation of ca2+ and Po4- in saliva
Bacteria initiates crystal growth and a high pH is needed to promote mineralisation

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22
Q

What is the high pH due to in the mouth for calculus formation?

A

Presence of carbonic acid, which is formed because of a reaction between CO2 we breathe and saliva

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23
Q

How does supragingival plaque form?

A

Due to the presence of mineral salts in the saliva

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24
Q

Where is supragingival plaque found?

A

Near sites of saliva pooling and is easy to remove by the dentist
Lingual to the lower anterior teeth
Buccal to the upper posterior teeth

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25
How does subgingival plaque form?
Due to the presence of mineral salts in the inflammatory exudate
26
How does subgingival plaque differ from supragingival plaque?
Subgingival plaque has a high pH and more difficult to remove
27
What is the non-specific plaque hypothesis of periodontal disease?
The total amount of plaque present in a person's mouth determines the pathogenicity of the disease, and to the number of bacterial species present But as plaque matures, microbial succession occurs
28
What is the specific plaque hypothesis of periodontal disease?
Periodontitis is caused by a single species of bacteria in plaque But research shows there is no 'single' pathogen present in every individual with periodontitis
29
What is the ecological plaque hypothesis of periodontal disease?
The more accumulation of bacteria, the more inflammation, the deeper the crevice therefore more anaerobic bacteria This changes the availability of nutrients These changes enable the succession of different species
30
What is the keystone plaque hypothesis of periodontal disease?
Certain low-abundance pathogens can orchestrate inflammatory diseases by remodelling a normally benign microbiota into a dysbiotic state
31
What is inflammation?
A protective tissue response to irritation, injury or infection, which serves to destroy or dilute both the injurious agent and injured tissues
32
What are the classic signs of inflammation?
``` Pain heat redness swelling loss of function ```
33
What are the clinical signs of inflammation in gingivitis?
Stable attachment level No bone loss The JE is at the level of the cement-enamel junction
34
What is the primary etiological factor of periodontitis?
Plaque
35
What are the local contributing factors on periodontitis?
Calculus Faulty restorations Developmental anomalies Patient habits
36
What are systemic factors of periodontitis?
Diabetes Smoking Immunodeficiencies
37
What are the stages of gingivitis?
Initial lesion Early lesion Established lesion Advanced lesion
38
What is the initial lesion of gingivitis?
Due to the presence of gram-positive anaerobic species that induce inflammation in the free gingiva Vasodilation of capillaries in the free gingiva and increase in neutrophils The infiltrate is confined to small areas of the connective tissue under the JE
39
When does the initial lesion occur?
24-48 hours of plaque accumulation
40
When does the early lesion occur?
4-7 days after plaque accumulation
41
What occurs during the early lesion?
Increased inflammatory infiltrate Loss of fibroblasts and collagen in infiltrated areas to accommodate the increasing amount of inflammatory agents Proliferation of JE and rete peg formation Increased GCF production
42
What are clinical signs of early lesions?
Bleeding on probing may occur due to increased vasodilation
43
When does the established lesion occur?
14-21 days after plaque accumulation
44
What occurs during the established lesion?
Gingival connective tissue largely replaced by inflammatory infiltrate Cannot see fibroblasts or collagen in free gingiva Increasing number of neutrophils, lymphocytes and plasma cells
45
What are clinical signs of established lesion?
Blood stasis | Epithelial ulcerations
46
What is the advanced lesion?
The inflammatory infiltrate affects the alveolar bone causing alveolar bone loss
47
What happens when we probe the gingival sulcus?
The probing is upto 3mm and there is no bleeding
48
What happens when we probe a gingival pocket?
The probing is greater than 3mm and there is bleeding on probing due to vasodilation
49
What are signs of healthy periodontal tissue?
Has an intact alveolar bone that is located 2-3mm apically from the cementum-enamel junction The JE is at the level of the cementum-enamel junction Probing pocket is 3mm without bleeding on probing
50
What are the clinical signs of gingivitis?
More than 3mm probing pocket with bleeding on probing The JE is still at the level of the cementum-enamel junction Alveolar bone was intact
51
What are the signs of periodontitis?
Resorption of the alveolar bone, typically 2-3mm apically from the cementum-enamel junction Greater probing pocket
52
How is periodontal tissue damage caused?
20% of tissue damage is caused by the direct action of microorganisms 80% of periodontal tissue damage is caused by de-regulated inflammatory response to dental plaque
53
Why does the JE migrate apically in periodontitis?
It migrates into the space of the destroyed gingival connective tissue due tot destroyed collagen gingival fibres and periodontal ligament fibres
54
How does the periodontal ligament breakdown?
Breakdown of collagen fibres inserting between the alveolar bone and cementum, by proliferation of inflammatory filtrate Damaged fibroblasts as there is a reduction in fibres ad ground substance of PDL There is a build up of host factors in connective tissue, which leads to destruction of periodontal fibres
55
How does the cementum become necrotic?
Destroy PDL means | Cementum can now not get nutrients from blood vessels in PDL so it becomes necrotic
56
How does alveolar bone get damaged?
LPS stimulate the release of cytokines, leukotrienes, prostaglandins which activate osteoclasts
57
Why are there more anaerobic species in the gingival sulcus?
They are in deeper areas which have less oxygen in the gingival and periodontal pockets
58
What is necrotising periodontal disease characterised by?
Fuso-spirochaetal complexes that invade host gingival tissues
59
What antibiotics are used during periodontal therapy?
Pencillin Tetracylins Metronidazole
60
What does penicillin do?
Inhibits cell wall synthesis
61
What does tetracyclins do?
Inhibit protein synthsis
62
What does metronidazole do?
Inhibits nucleic acid synthesis
63
What are the stagnant areas where there are abundance of dental plaque?
Along the gingival margin and inter proximal areas
64
How do disclosing agents work?
Change the colour of dental biofilm to provide a contrast with the tooth surface Biofilms have the capacity to retain large amounts of dye substances due to interactions with biofilm components
65
How does the two tones work in disclosing agents?
Stains early biofilm which is less than 3 days old with reddish pink and mature biofilm which is more than 3 days old with a blue colour
66
What are the advantages of disclosing tablets to the dentist?
visualising dental biofilm Color guides biofilm removal Take plaque indicies
67
What are the advantages of disclosing tablets to the patient?
Shwon where they need to brush better | Motivation and education
68
What are the plaque index scores?
3- thick plaque visible along the gingival margin (no need to probe) 2- plaque is visible along the gingival margin, with or without air drying (no need to air probe) 1- following air drying, plaque is no visible but can be wiped using an explorer) 0- Following air drying, plaque is not visible nor can be wiped off
69
What is recorded if an index tooth is missing?
Score the nearest tooth that is in that sextant | If there are no teeth enter X
70
What is recorded if the plaque thickness varies across the gingival margin?
Score according to the worst situation
71
What s the overall place index score?
Sum of the 12 surface scores | Both buccal and lingual -max of 36
72
What is the O'Leary plaque score?
Determines if plaque is present or not on the 4 surfaces of the tooth
73
What are the scores of O'Leary?
0 if there is no plaque and 1 if there is plaque | Score is expressed as a percentage of all surfaces
74
What O'Leary score is considered appropriate oral hygiene?
20%

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