OE L29 Integuments

Question 1

What are integuments?

Answer 1

Substances that form on the surfaces of teeth.

Question 2

Give examples of coatings with developmental origins.

Answer 2

• Cuticle
• Reduced enamel epithelium
• Coronal cementum

Question 3

Give examples of acquired coatings.

Answer 3

• Enamel pellicle
• Plaque (colonisation by bacteria)
• Calculus

Question 4

Describe the pellicle.

Answer 4

• A protein layer on the enamel surface, to which bacterial species and their metabolic products can adhere to.
• Predominantly present close to the ginigval margin.

Question 5

What are the main contibutors to the pellicle?

Answer 5

• Proteins from saliva, GCF, serum
• CT metabolites
• Bacterial products/metabolites
• Cellular products/metabolites

Question 6

Describe the development of the pellicle.

Answer 6

• Extremely quick
• First layer forms in less than 5 seconds
• Low molec. weight proteins laid down first
• Pellicle matures over several days and becomes 10um thick
• Has surface and subsurface layers

Question 7

What proteins are found in the pellicle?

Answer 7

• Mucins
• Amylase
• Cystatin
• Statherin
• Histatins
• Proline rich proteins

Question 8

What are the main adhesive forces involved in pellicle formation?

Answer 8

• Ionic interactions (main force)
• Van der Waals forces
• Hydrogen bonds
• Hydrophobic interactions

Question 9

Which molecules interact with calcium ions in HAP?

Answer 9

• Sulphated glycoproteins e.g. mucins

- Phosphoproteins (directly or via phosphor-calcium bridge)

Question 10

How can calcium binding cause increased bacterial binding?

Answer 10

• Sometimes, the interaction between the phosphoprotein and calcium causes a conformational change in shape of the protein
• This can expose hydrophobic regions which can be used for bacterial receptor binding

Question 11

What are the major functions of the pellicle?

Answer 11

• Protection against acids
• Protects enamel from abrasion
• Assists in re-calcification of enamel defects
• Provides a continous layer of protective proteins at enamel-gingival interface to protect from decay
• Provides surface for the absorption of bacteria

Question 12

Outline bacterial colonisation of the pellicle.

Answer 12

Proteins stick to the tooth; bacteria stick to proteins.

Formation of a matrix which stabilises interactions between the pellicle and bacteria.

Question 13

Describe the 4 stages of plaque formation.

Answer 13

1. Transport of bacteria to tooth surface
2. Reversible adsorption of bacteria onto pellicle surface (passive means)
3. Attachment of bacteria becomes less reversible, a matrix of cross linked sugars is synthesised by bacteria to stabilise themselves
4. Growth of different organisms, diverse bacterial community of many species established

Question 14

Describe the initial reversible interactions between pellicle proteins and microorganisms.

Answer 14

• Long-range interactions form between proteins and microorganisms
• These interactions are electrostatic (ionic and hydrogen) and van der Waals forces
• Interactions usually occur via calcium bridging

Question 15

Describe the less reversible attachment of bacteria (later stages of plaque formation).

Answer 15

• Short-range interactions between adhesins on microbial surface and proteins in the acquired pellicle
• Very strong and specific

Question 16

Which 2 other factors can allow bacterial adhesion?

Answer 16

• Confirmational changes of proteins on adsorbed surfaces can allow bacteria to bind
• Bacterial neuraminidase action can remove sialic acid, facilitating bacterial adhesion

Question 17

Describe the main functions of bacterial adhesion proteins.

Answer 17

• Surface of bacteria, e.g. streptoccoi have long adhesion proteins which have n-terminal binding sites for mucins on the pellicle
• There are variants of adhesion proteins which have different recognition motifs for pellicle proteins e.g. serine-rich repeat proteins recognise sialic acid in mucin

Question 18

Which receptor on streptococci can bind to gp-340 thus preventing bacterial aggregation?

Answer 18

Antigen I/II polypeptides (Ag I/II)

Question 19

Describe pili and fibrillar adhesion proteins.

Answer 19

• Further type of adhesin
• Can be very long (up to 3um)
• Can bind to ECM and cell surfaces, some bind to salivary pellicle proteins
• They are required for complex biofilm formation

Question 20

What are fimbriae?

Answer 20

Long filamentous polymeric protein structures located at the surface of bacterial cells.
Fimbrae can have one or more adhesive domains.

Question 21

Distinct fimbrae allow interactions with specific components, give examples of these interactions.

Answer 21

• S.gordonii with amylase
• A.naeslundii with statherin
• S.mutans and P.gingivalis can interact with HAP treated with proline-rich proteins (PRPs)

Question 22

What do hydrophobic fimbrae interact with?

Answer 22

Hydrophobic portions of salivary proteins.

Question 23

Some bacterial proteins are “lectin-like”, what can they bind to?

Answer 23

• Carbohydrates or oligosaccharides within salivary glycoproteins

Question 24

Describe the basis of colonisation.

Answer 24

• There are early colonisers e.g. streptoccoi
• Bridge colonisers act as a bridge between early and late colonisers e.g. F.nucleatum has adhesins to connect to S.mutans
• Late colonisers .e.g P.gingivalis can bind to F.nucleatum

Question 25

Have vaccines against F.nucleatum been successful in preventing gingivitis?

Answer 25

Yes in mice studies there was reduced gingival inflammation.