The Oral Environment 1-3 Flashcards
1
Q
What are the functions of oral fluids?
A
Protective: cleansing, mucosal protection, buffering, remineralisation, antimicrobial
Digestive: taste, digestive enzymes, lubricates bolus for chewing, swallowing
2
Q
What is a prominent symptom for patients with salivary gland disease?
A
Xerostomia (dry mouth)
3
Q
What effects can reduced salivary flow have on oral health?
A
- Increased incidence of dental caries
- Caries present on buccal and labial surfaces
4
Q
Caries resulting from lack of salivary flow would likely be present on which tooth surfaces?
A
Buccal and labial surfaces
5
Q
What type of glands are salivary glands?
A
Exocrine
6
Q
What type of secretions do salivary glands produce?
A
Serous and/or mucous secretions
7
Q
What arrangement do salivary glands have?
A
Compound, tubulo-acinar arrangement
8
Q
Which layer of the oral mucosa contains minor salivary glands?
A
Lamina propria
9
Q
What are the major salivary glands?
A
Parotid, submandibular, sublingual
10
Q
What are the minor salivary glands?
A
- Buccal
- Labial
- Lingual
- Palatal
11
Q
Which major salivary gland has serous secretions?
A
Parotid
12
Q
Which major salivary gland has mixed serous/mucous secretions?
A
Submandibular
13
Q
Which major salivary gland has mucous secretions?
A
Sublingual
14
Q
Describe the type of secretions produced by the minor salivary glands
A
Buccal - mucous
Labial - mucous
Lingual - serous and mucous
Palatal - mucous
15
Q
What is gingival crevicular fluid (GCF)?
A
Fluid from the epithelium lining the gingival crevice (sulcus)
16
Q
Describe the flow rates of gingival crevicular fluid in health and inflammation states
A
Little GCF from healthy gingivia, but flow increases with inflammation e.g. gingivitis
17
Q
Which salivary gland is produces most saliva when you sleep?
A
Submandibular gland
18
Q
When is salivary flow rate the highest: sleeping, awake or eating?
A
Eating
19
Q
When is salivary flow rate the lowest?
A
Sleeping
20
Q
What is the average daily salivary flow in ml?
A
500-700ml
21
Q
Which is the major salivary gland when eating?
A
Parotid
22
Q
Which salivary gland produces most saliva when awake (not eating)?
A
Submandibular
23
Q
Which factors can affect unstimulated salivary flow rate?
A
- State of hydration
- Previous stimulation
- Circadian rhythms
- Circannual rhythms
- Medications
- Salivary gland disease
24
Q
Describe the composition of saliva
A
Inorganic:
Water = 99.5%
Ions = 0.2%
Organic:
Proteins - 0.3%
25
When is bicarbonate ion concentration highest?
At higher salivary flow rates
26
What is bicarbonate important for in the oral cavity?
Buffering plaque acids
27
What is the function of fluoride in saliva?
- Antibacterial
- Forms fluoroapatite
- Promotes remineralisation
28
What is the function of calcium and phosphate in the saliva?
Remineralisation
29
What is the role of thiocyanate in the saliva?
Antibacterial
30
When is bicarbonate most effective at buffering?
At high salivary flow rates, when [HCO3] is highest
31
When are phosphates important for buffering?
At rest
32
Which pH do proteins have their main buffering action at?
pH <5
33
Which enzyme converts water and carbon dioxide into carbonic acid (H2CO3)?
Carbonic anhydrase
34
Describe the stages in saliva secretion
1. Acetylcholine (ACh) induces calcium release
2. Calcium works on channels to bring Cl- to the lumen
3. ATP exchange (3Na+ in, 2 K+ out), sodium is brought through the membrane to pair with chloride (NaCl)
4. Osmotic pressure drives water into the lumen
35
What is amylase?
- Enzyme produced in saliva
| - Hydrolyses alpha-1,4-glycosidic bonds in starch
36
What is lysozyme?
- Role in non-specific defence
- Present in many secretions: saliva, tears, vaginal mucous
- Attacks bonds in bacterial cell walls, causing lysis
37
What is lactoperoxidase?
- Enzyme from salivary glands and some bacteria
- Allows oxidation of SCN- -> OSCN-
- Has antibacterial action
38
What are cystatins?
- Inhibit cysteine proteases, especially in bacteria
| - Antimicrobial function
39
What is gustin?
- Zinc-containing protein
- Facilitates taste by activating taste buds
- CO2 + H2O -> H+ + HCO3-
- Potent PDE 5 activator
40
What are histatins?
- Histidine rich proteins
- Inhibit CaPO4 precipitation
- Antimicrobial
- Inhibits: candida albicans, streptococcus mutans
41
What is the role of immunoglobulins in the saliva?
- From plasma cells in salivary glands
- Secretory IgA
- Confers specific immunity against bacteria
- Basis of vaccination vs. S mutans
42
What is lactoferrin?
Iron-binding protein
Binds Fe3+
Antibacterial
43
What is lipase?
- Breaks down lipids/hydrolyses triglycerides
- Lingual lipase
- From von Ebner glands on tongue
- May assist in digestion of milk
44
What are mucoproteins ('mucins')?
- CHO-protein macromolecules
- Bind to tooth and epithelial surfaces
- Protective role, lubrication
- Affects bacterial adhesion
- Promotes bacterial aggregation -> easier clearance from mouth
45
What are proline-rich proteins (PRPS)?
- Inhibit growth of Ca3PO4 crystals
- Anticalculus effect?
- Adsorbs onto hydroxyapatite
- Decreases mineral loss
- Resists acid attack
- Allows remineralisation
- Regulates bacterial attachment
46
What are statherins?
- Prevent precipitation of Ca3PO4 from saliva
- Saliva is supersaturated with Ca2+ and PO4
- Anticalculus action
47
What are some examples of plasma-derived substances that 'spill over' into saliva?
- Proteins e.g. albumins
- Blood group substances
- Immunoglobulins (IgG)
- Hormones
- Drugs
48
What are conditioned responses?
Learned; acquired by association
| e.g. Pavlov's experiments
49
What are unconditioned responses?
Unlearned, innate responses
50
Give examples of unconditioned salivary stimuli
Mechanical: pressure on the PDL/oral mucosa
Chemical: gustation, olfaction, common chemical sense
51
Define ipsilateral
Same side of the body
52
What does pressure on the PDL (e.g. chewing) result in?
Increased salivary flow from ipsilateral glands
53
Where are taste buds located?
Tongue dorsum, palate and epiglottis
54
Describe the order of potencies for producing saliva from high to low
Acid > umami > sweet > bitter
55
Which 'taste' is salivary response greatest for?
Acidic
56
Which 'taste' generates the lowest salivary response?
Bitter
57
What is common chemical sense?
- A primitive response to irritants, injury
- Mediated by nociceptors in mucous membranes
- Contribute to 'taste' of spices
58
What is conditioned salivary stimuli?
Learned responses to:
- 'psychic' stimuli (thinking about food)
- visual stimuli
- auditory stimuli e.g. Pavlov's experiments
- Responses are easily lost (become 'extinct') if not regularly reinforced
59
How can a conditioned stimulus cause a response on its own?
Pair conditioned stimulus (e.g. buzzer) with an unconditioned stimulus (e.g. food), repeat the 2 stimuli together. Eventually, conditioned stimuli will produce a response on its own.
60
How is salivation controlled?
By the autonomic nervous system
Both parasympathetic and sympathetic nervous systems act to increase salivary secretion
Sympathetic nervous system stimulates more mucous salivation
61
Describe the parasympathetic controls of saliva secretion
Parasympathetic nervous system: increases saliva secretion, increases blood flow (vasodilation)
62
Describe the sympathetic controls of saliva secretion
Sympathetic nervous system: increases saliva secretion, decreases blood flow (vasoconstriction)
63
Describe the 2 stage mechanism of salivary secretion
Stage 1: primary secretion in acinus
| Stage 2: ductal modification
64
Describe stage 1 of salivary secretion (primary secretion in acinus)
- Chloride is pumped into the lumen, Na+ crosses over membrane and combines with chloride forming NaCl
- Water forced into lumen by osmotic pressure
- Carbon dioxide from blood combines with water in presence of carbonic anhydrase, forms carbonic acid
- Carbonic acid dissociates to form bicarbonate and hydrogen
65
Describe stage 2 of salivary secretion (ductal moification)
- Primary saliva is modified as it moves through the striated duct
- Na+ and Cl- reabsorbed
- HCO3- and K+ secreted
- Final saliva is hypotonic to plasma
- Some proteins are secreted by the ducts
66
What is the volume of saliva in the mouth?
~1.1 ml (range = 0.5-2.1 ml)
67
What area is saliva in the mouth dispersed over?
~200 cm2
68
How thick is the film of saliva covering the mucosa?
50-100 micrometres thick
69
Salivary flow velocity rates vary in different regions of the mouth. Where is it highest/lowest?
- Highest in lower lingual region
| - Slowest in labial and buccal regions
70
Differences in salivary flow velocity rates in different regions of the mouth may influence what?
The incidence of caries in different regions of the mouth - cariogenic sugars are retained longer in regions where flow is slowest
71
Which region of the mouth has the highest salivary flow velocity rate, anterior or posterior?
Posterior (increase in flow rate moving from anterior to posterior region)
72
Where does calculus tend to build up?
Lower regions
73
What is calculus?
The mineralisation of dental plaque - increased saliva in lower lingual regions -> increased calcium phosphate -> increased calculus in these regions
74
What is 'clearance'?
Clearance refers to the rate at which substances are removed from the mouth
75
Which factors influence clearance?
- Salivary film velocity
| - Location in the mouth
76
What is the benefit of low salivary flow rates?
Retention of beneficial substances e.g. fluoride, chlorhexidine
77
What is the benefit of high salivary flow rates?
Removal of harmful substances e.g. sucrose
78
What is the Stephan curve?
A graph of the plaque pH change over time is called a Stephan curve
79
What is the critical pH on a Stephan curve?
The pH at which plaque can start to remove elements form the tooth. Anything below critical pH creates caries. Above critical pH = remineralisation
80
How does chewing gum increase salivary flow?
Stimulates the periodontal ligament (mechanoreceptors)
81
What effect does chewing gum have on the sugar challenge?
pH drop is reduced, returns to normal pH quicker.
82
What is the sugar challenge?
Cup of sugary liquid held in the mouth, spit it out. Measure pH changes over time.
83
How does increased salivary flow neutralise plaque acid?
By increasing bicarbonate content of saliva. Bicarbonate acts as a buffer - resists pH changes
84
How is plaque protected against salivary flow?
Structural network of insoluble sugars inside plaque
85
Which carbohydrates (mainly) cause caries?
Fermentable carbohydrates
86
What is the benefit to oral health of alternative sweeteners?
Alternative to fermentable carbohydrates: have a sweet taste but not metabolised to acids by plaque bacteria
87
What are the types of sweeteners?
- Bulk caloric/low caloric sweeteners
| - Non-calorie, high intensity sweeteners
88
Which sweeteners are classed as bulk caloric (cariogenic)?
Sucrose, fructose, glucose, lactose
89
Which sweeteners are classed as non-caloric/high intensity?
Aspartame, cyclamates, saccharin, sucralose
90
Which sweeteners are classed as low caloric?
Mannitol, sorbitol, xylitol
91
Which sweetener is commonly found in chewing gum?
Xylitol
92
Which sweetener has a laxative effect?
Xylitol
93
When do patients tend to complain of dry mouth?
When salivary flow rates fall below 50% of normal levels
94
What would cause a reduction by 50% of normal salivary flow rate?
Loss of function of more than one major salivary gland
95
What are the causes of decreased salivary flow?
- Side effect of many drugs
- Radiotherapy (for head and neck tumours)
- Diseases: specific salivary gland disease, systemic diseases that affect salivary glands, fluid/electrolyte loss
96
What is the BNF and what does it do?
British National Formulary
| Provides up-to-date information on medicines
97
What is Sjorgen's syndrome?
Autoimmune condition that affects salivary glands. Most common glad affected is lacrimal glands. Dry eyes and dry mouth are symptoms.
98
What type of caries are associated with reduced salivary flow
Smooth surface caries
99
What are the consequences of reduced salivary flow?
- Increased dental caries
- Increased oral diseases (stomatitis, fissured lips)
- Dysaesthesia (burning mouth)
- Impaired oral function (chewing, swallowing, speaking)
- Diminished taste perception
100
What is oral dysaesthesia?
Sensation of having a burning mouth
101
How can xerostomia be managed?
- Depends on the cause
- If there is functioning salivary gland tissue present: stimulate salivary flow by chewing, or drugs
- If there is no functioning salivary gland tissue, saliva substitutes may be used: mucin based; cellulose based
