OCB02-2022

Question 1

Describe the whole mouth unstimulated salivary flow rate.

Answer 1

0.35ml/min but shows circadian rhythm

Lowest from 6-9am and highest from 3-6pm

Question 2

What is the whole mouth salivary flow rate during sleeping?

Answer 2

0.1ml/min

Question 3

What is the whole mouth stimulated salivary flow rate?

Answer 3

2ml/min

Question 4

How much saliva is produced in 24 hours?

Answer 4

~600ml

Question 5

On average, how much of the day is spent experiencing unstimulated, stimulated and sleeping salivary flow rates?

Answer 5

Unstimulated = 15hrs

Stimulated = 2hrs

Sleeping = 7hrs

Question 6

What might be the reason for a lower salivary flow rate during sleeping?

Answer 6

Decreased CNS higher centre activity so loss of positive effect on salivary nuclei

Question 7

What are each of the salivary glands contributions to whole mouth salivary flow rates at rest/unstimulated?

Answer 7

Parotid = 28% or 0.1ml/min

Submandibular/sublingual = 68% or 0.24ml/min

Minor = 4% or <0.05ml/min

Question 8

What are each of the salivary glands contributions to whole mouth salivary flow rates during stimulation?

Answer 8

Parotid = 53% or 1.05ml/min

Submandibular/sublingual = 46% or 0.92ml/min

Minor = 1% or <0.1ml/min

Question 9

Which salivary glands contribute the most to each of unstimulated and stimulated salivary flow rates?

Answer 9

Unstimulated = submandibular/sublingual (68%)

Stimulated = parotid (53%)

Question 10

What is the consistency of saliva at rest and why?

Answer 10

Thick, sticky

Larger contributions from submandibular and sublingual glands = more mucin (also from minor glands)

Protective/covers surfaces

Question 11

What is the consistency of saliva at rest and why?

Answer 11

Watery

Larger contributions from parotid glands

Moistens food and initiates digestion

Question 12

What unstimulated salivary flow rates are considered normal and low?

Answer 12

Normal = >0.25ml/min

Low = 0.1-0.2ml/min

Very low = <0.1ml/min

Question 13

What stimulated salivary flow rates are considered normal and low?

Answer 13

Normal = >1.0ml/min

Low = 0.7-1.0ml/min

Very low = <0.7ml/min

Question 14

What can decrease salivary flow rate?

Answer 14

Age

Certain prescribed medications

Question 15

Does the size of salivary glands affect salivary flow rate?

Answer 15

Yes - larger glands have higher flow rates (so males > females)

Question 16

Is the salivary film thinner on soft or hard surfaces?

Answer 16

Thinner on hard surfaces

Question 17

On which part of the oral mucosa is the salivary film thickest?

Answer 17

Anterior tongue (50μm)

Question 18

On which part of the oral mucosa is the salivary film thinnest?

Answer 18

Hard palate (10μm)

Question 19

What do people with dry mouth experience?

Answer 19

Dry mouth during the day

Night waking due to dryness

Burning sore mouth and tongue

Candidiasis

Bad taste

Dental caries

Denture discomfort

Difficulty speaking, swallowing, eating

Question 20

How many bacteria are in saliva?

Answer 20

~10^8/ml

Question 21

Name some things found in saliva.

Answer 21

Epithelial cells, neutrophils

Micro-organisms

Exosomes

Mucins (MUC5B, MUC7)

Electrolytes/ions

Antibodies (IgA and IgG)

Hormones, cytokines, enzymes

Question 22

What are the 4 main functions of saliva?

Answer 22

Tooth protection

Protection and maintenance of oral mucosa

Regulation of oral microbiota

Taste and processing of food and nutrients

Question 23

Describe the tooth protection role of saliva.

Answer 23

Increased flow rate = increased clearance of sugar and bacteria to decrease risk of caries

pH buffering with bicarbonate and carbonic anhydrase 6 (stimulated = 30mmol) to neutralise acids and prevent hydroxyapatite dissolution

Acquired enamel pellicle (<1μm) prevents surface mineralisation but increases sub-surface remineralisation; decreases friction by 20x to decrease abrasion

Saliva supersaturation with calcium phosphate (resting = 2mmol) and calcium binding proteins (eg statherins) to stimulate remineralisation

Question 24

Describe the protection and maintenance of oral mucosa role of saliva.

Answer 24

Salivary film contains a network of protein with pores = formed of mucin (MUC5B)

This allows <100nm soluble globular proteins (eg albumin) through easily but restricts movement of larger objects like bacteria to act as a barrier

Increases lubrication of oral tissues

Moistening and hydration aid in wound healing

Question 25

Describe the regulation of oral microbiota role of saliva.

Answer 25

Maintain normal numbers and composition of oral microbiota

Saliva flow clears some microbes

Acquired enamel pellicle modifies adherence of microbes to teeth by acting as binding sites for commensals

Agglutinins, mucins and other proteins aggregate microbes to facilitate their clearance from the mouth

Salivary proteins can modulate microbial growth - eg sugars on mucins

Many antimicrobial growth-limiting factors in saliva = histatins, IgA, defensins

Question 26

Name some primary colonisers and what molecules they adhere to in the acquired pellicle.

Answer 26

S.oralis, S.gordonii, S.sanguis

Sialylated mucins

Proline-rich proteins

Salivary agglutinin

Bacterial cell fragments

α-amylase

Question 27

Name some antibacterial compounds found in saliva.

Answer 27

Cystatins, histatins

Defensins

Cathelicidins

Lysozyme

Lactoperoxidase

Lactoferrin

Chromogranin A

Immunoglobulins

PLUNCs

Question 28

Name some antifungal compounds found in saliva.

Answer 28

Histatins

Defensins

Cathelicidins

Chromogranin A

Immunoglobulins

Mucin-derived proteins

Question 29

Name some antiviral compounds found in saliva.

Answer 29

Cystatins

Mucins

Immunoglobulins

SLPI