Aetiology of periodontal disease

Question 1

What groups can periodontal diseases go into?

Answer 1

• Periodontal health, gingival diseases and conditions (only affecting soft tissues)
• Periodontitis (affecting all the periodontal apparatus e.g. gingiva, periodontal ligament, cementum and the alveolar bone)
• Other conditions affecting the periodontium
• Peri-implant diseases and conditions

Question 2

Give a definition of periodontal disease and how this changes in healthy and diseased sites

Answer 2

• Bacterially-induced, immune-mediated inflammatory diseases of the tissues supporting the teeth
• Healthy = well defined, precise locations, effective immune response
• Diseased = exacerbated, uncontrolled, detrimental immune response

(Normal bacteria shown on the left and can form in healthy-areas. There is a constant flow of neutrophils, low level of inflammation that protects us from the bacterial invasion.
In the diseased periodontal mouth, there is a different set of bacteria which are present in the sub gingival areas. These bacteria can cause detrimental host responses. The host immune response on the disease side, this is uncontrolled and leads to tissue damage.)

Question 3

Give a definiton of inflammation

Answer 3

A protective tissue response to irritation, injury or infection, which serves to destroy, dilate or wall off both the injurious agent and the injured tissues. Clinical signs are pain, heat, swelling and loss of function.
All cells of the periodontal tissue are involved in this inflammatory response apart from the red blood cells.
All the immune cells produce enzymes and inflammatory mediators to damage the connective tissue. This is why we see the damage to alveolar bone during the development of periodontal disease.

Question 4

What are the 3 prerequisites for periodontal disease initiation and progression?

Answer 4

1. The virulent periodontal pathogens (adhesins, co-aggregation, invasion)
2. Local environment
3. Host susceptibility (gene polymorphism, smoking, diabetes, immunosuppression)

Question 5

What are the 3 main factors which need to be in a harmonious relationship?

Answer 5

• Susceptible host
• Micro-organisms
• Environmental trigger

Breakdown of this leads to disease.

Question 6

Why is the mouth a good microbial habitat?

Answer 6

The properties of the mouth make is ecologically distinct from all other surfaces.
It has mucosal surfaces (lips, cheek, palate, tongue) and it has hard shedding tooth surface. Hard surfaces are where the biofilm forms.
There are supra gingivial surfaces that as smooth with pits and fissues and sub - gingival surfaces which have gingival crevicular fluid.

Question 7

What is the main bacteria present in the mouth?

Answer 7

Streptococcus

Question 8

What is the difference between planktonic and sessile bacteria?

Answer 8

Planktonic cells can float in saliva or sessile cells are attached to the mucosa or hard surfaces.

Question 9

Why cant bacteria form on the soft surfaces?

Answer 9

these surfaces are constantly shedding and the biofilm takes time to grow

Question 10

What are the advantages to a bacteria of living in plaque?

Answer 10

• nutrient availability
• cell-cell signalling
• gene transfer
• protection from harmful factors

Question 11

What is the definition of plaque?

Answer 11

A complex microbial community that develops on the tooth surface and other non-shedding materials, embedded in a matrix of polymers of bacterial and salivary origin.

Question 12

Give some differences between supra and sub gingival plaque?

Answer 12

Supra:

• nutrients are diet and saliva
• carbohydrates are the principal energy source
• firmly adhered
• higher oxygen tension
• aerobes

Sub:

• nutrients from gingival cervicular fluid
• proteins as a source of energy
• many motile forms
• reduced redox potential
• anaerobes

Question 13

What was the main discovery found from the gingivitis exeriment?

Answer 13

When the plaque is removed, the gingival inflammation is restored.

Question 14

What are the two main local factors (plaque retentive factors) for periodontitis?

Answer 14

• dental calculus

- lack of saliva

Question 15

Give some details on dental calculus

Answer 15

Mineralised dental plaque covering the enamel or root surface
Calcium and phosphate crystals
Supra-gingival: found in sites of saliva pooling, light coloured and frosted
Sub-gingival : found in periodontal pockets, hard and dark, difficult to remove
Acts as a plaque trap
Removed professionally

Question 16

Give 7 local plaque retentive factors

Answer 16

1. Tooth position
2. Gingival anatomy
3. Tooth shape / abnormalities
4. Root anatomy
5. Carious cavities
6. Overhanging restorations
7. Removable prostheses / appliances

Question 17

How does tooth position lead to plaque retention?

Answer 17

malalignment and crowding (increase space for plaque accumulation, need to teach patient how to remove plaque), open contacts (food packing, need to show the patient how to remove the food from here)

Question 18

How does gingival anatomy lead to plaque retention?

Answer 18

gingival overgrowth will be a plaque trap, tooth surfaces covered, difficult to remove plaque

Question 19

Give one example of tooth abnormalities that can lead to plaque retention

Answer 19

Enamel projections

Question 20

What are the 3 root abnormalities that can lead to plaque retention?

Answer 20

1. Furcations of molars / premolars (where the roots divide, usually covered by bone but if there is bone loss it will provide an additional surface for plaque retention
2. Root depression e.g. canine fossa 1st premolars - bone loss will expose the area
3. Root groves - unevenness in the tooth surface is another plaque retentive feature

Question 21

What are the two ways that caries and restorative margins lead to plaque retention?

Answer 21

Carious cavities

Overhanging restorations

Question 22

How can lack of saliva lead to plaque retention? Gove some details on lack of saliva.

Answer 22

• Xerostomia (dry mouth) - lack of salivary flow that can increase gingival inflammation due to lack of salivary antibacterial factors

Commonly seen in …

• Mouth breathers
• Incompetent lips
• Drying of labial tissues
• Patients taking poly pharmacy (many medications) can cause it
• Patients with certain condition e.g. Sjogren’s syndrome
• Salivary gland disease - damage to these can results in less saliva and may cause gingival inflammation secondary to increased plaque accumulation

Question 23

What are systemic factors leading to periodontitis and give 5 examples?

Answer 23

These modify the prevention of periodontal disease and may determine susceptibility to periodontitis.

Including:
Smoking
Diabetes
Pregnancy
Medications that cause gingival enlargement 
Genetic factors

Question 24

How does smoking increase likelihood of periodontitis?

Answer 24

More likely to develop periodontitis and experience greater bone loss than non smokers. They are more likely to develop periodontal pockets and loose teeth. Smokers respond less well to treatment than non-smilers. Smoking masks gingivitis effects so will experience less bleeding (reduced gingival blood flow), it impairs wound heeling and increases inflammation.

Question 25

Give some details on diabetes and how it can lead to periodontitis

Answer 25

• Type 1 diabetes (insulin dependant)
• Type 2 diabetes (insulin resistant) - associated with diet and obesity
• Uncontrolled / poorly controlled (poor glycemic control) increases risk of periodontal disease and disease progression
• Impaired immune response
• Impaired wound healing
• Recurrent / multiple periodontal accesses
• Dentist should stress importance of good glycemic control in the patient
• Successful periodontal treatment improves glycemic control

Question 26

How does pregnancy increase likelihood of periodontitis?

Answer 26

hormones may increase gingival response to plaque
Increased progesterone results in increases gingival blood flow
Similar effects also seen at puberty and associated with the contraceptive pill

Question 27

Give some examples of medication affecting likelihood of periodontitis?

Answer 27

Drugs that induce gingival overgrowth, gum covers many tooth surfaces

Calcium channel blockers - for hypertension
Phenytoin - for epilepsy
Ciclosporin - immunosuppressant prescribed for some autoimmune disorders

In severe cases, treatment won’t work and may need to communicate with patients GP to consider alterations to their medication

Question 28

What is the difference between genetic polymorphism and single gene defects?

Answer 28

Genetic polymorphisms are common: normal variations in gene structure, may occur in regulatory or coding regions of the gene

Hereditary conditions are rare: single point genetic mutations