The Formation of Dental Integuments

Question 1

What is an integument?

Answer 1

An outer covering

Question 2

Give examples of the integuments found in the mouth

Answer 2

Acquired pellicle, dental plaque, dental calculus (supra and subgingival)

Question 3

What is the aetiological factor in major oral diseases and what diseases does this factor contribute to?

Answer 3

Plaque

caries, gingivitis and periodontitis

Question 4

What is the pellicle considered as?

Answer 4

The protective covering of the enamel

Question 5

How long does it take for the acquired pellicle to reach its maximum formation?

Answer 5

1-1.5 hrs

Question 6

Explain how the pellicle forms

Answer 6

1. Adsorption of
   salivary proteins & glycoproteins onto + ve charged enamel surface - A SELECTIVE PROCESS !
2. Modification of some glycoproteins in saliva by bacterial enzymes
3. Loss of solubility of glycoproteins
4. Pellicle layer assumes overall –ve charge

Question 7

What is the function of statherin?

Answer 7

Statherin is a protein in humans that is encoded by the STATH gene. It prevents the precipitation of calcium phosphate in saliva, maintaining a high calcium level in saliva available for remineralisation of tooth enamel and high phosphate levels for buffering

Question 8

What are the functions of the acquire pellicle?

Answer 8

1. lubrication
2. protects against acid attack
3. Promotes adhesion of gingival epithelium to tooth
4. Modulates growth of oral flora

Question 9

What are some of the protective components in the pellicle?

Answer 9

• acidic proline-rich proteins (PRPs)
• Satherins and histatins
• Albumin
• Lysozymes
• IgA
• Salioperoxidase
• Proteins from gingival crevicular fluid

Question 10

What are the functions of the following protective components of saliva?

1) acidic proline-rich proteins (PRPs)
2) Satherins and histatins

3) Albumin
4) Lysozymes
5) IgA

6) Salioperoxidase
7) Proteins from gingival crevicular fluid

Answer 10

1) The acidic proline-rich proteins will bind calcium with a strength which indicates that they may be important in maintaining the concentration of ionic calcium in saliva
2) Statherin prevents the precipitation of calcium phosphate in saliva, maintaining a high calcium level in saliva available for remineralisation of tooth enamel and high phosphate levels for buffering.

Histatin - most significant function of histatins may be their anti-fungal activity against Candida albicans and Cryptococcus neoformans

3) Ionic concentration?
4) Lyses bacteria - prevents overgrowth
5) Mucosal immunity

6) catalyses conversion of thiocyanate (SCN-) to
hypothiocyanate (OSCN–) = antibacterial

7) Contain antibodies = immunity

Question 11

What are histatins and what do they contain?

Answer 11

Small molecular weight peptides from parotid and submandibular glands

Contain histidine

Question 12

What is the purpose of histatins and what do they bind to?

Answer 12

anti-microbial

Bind to hydroxyapatite

Question 13

Which types of histatins are present in the acquired pellicle?

Answer 13

1,3 and 5

Question 14

Which type of histatins don’t bind hydroxyapatite?

Answer 14

Non-phosphorylated histatins

Question 15

Explain how salivary glycoproteins are modified by bacteria

Answer 15

Break down oligosaccharide side chains which make protein chains insoluble and they aggregate

Question 16

What are the immunological factors that lead to plaque overgrowth?

Answer 16

sIgA deficiency
Neutrophil dysfunction
Myelo-suppression
(decreased ability of bone
marrow to produce blood cells e.g. chemotherapy, AIDS)

Question 17

What are the non-immune factors that lead to plaque overgrowth?

Answer 17

Xerostomia
Antibiotics
Dietary carbohydrates
Increased GCF

Question 18

What are the properties of initial plaque?

Answer 18

Less adherent
Less potentially pathogenic
Few bacterial species

Question 19

What are the properties of mature plaque?

Answer 19

Increased mass & thickness
– Diverse microbial composition
– Potentially more pathogenic - can react to changes in the environment

Question 20

Name plaque retentive factors

Answer 20

– Orthodontic appliances
– Partial dentures
– Faulty restorations
– Calculus
– Deep periodontal pockets

Question 21

How does calculus form?

Answer 21

Deposition of
Ca and PO4 -containing
salts into plaque
• Begins within 24 - 72hrs and
up to 12d to mature
• Porous

Question 22

When does calculus form?

Answer 22

• Forms when solutions of Ca and PO4
ions become “unstable”
i.e., when no longer remain in solution
• Also occurs in kidney, gall bladder, urinary bladder and salivary glands
• Calculus surface provides site for further plaque growth

Question 23

What role do bacteria play in calculus formation?

Answer 23

Bacterial pyrophosphatase activity splits pyrophosphate in saliva to yield phosphate

Some bacterial membranes are organised into Ca-binding complexes

Question 24

How does sub-gingival (serumnal) calculus form and why is it usually pigmented?

Answer 24

Forms from GCF and perio pocket components

Pigmented due to haem components from haemoglobin

Question 25

What increases the rate of calculus formation?

Answer 25

– high salivary pH
– high salivary calcium concentration
– high bacterial protein and lipid concentration

Question 26

What factors affect the amount of calculus in a population?

Answer 26

• Oral hygiene habits
• Access to professional care
• Diet
• Age
• Ethnic origin
• Time since last dental cleaning

Question 27

What are the clinical implications of calculus?

Answer 27

• Sub- or supra-gingival calculus at gingival margin causes gingivitis
• Bacterial by-products induce inflammation and bleeding
• Can result in gingival recession
• Untreated gingivitis may lead to periodontitis

Question 28

How is calculus formation prevented?

Answer 28

1. zinc salts - poison the forming crystals
2. soluble pyrophosphate (di-phosphate) 1% w/v
   – delays plaque mineralisation