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IOE > saliva - biochemistry > Flashcards

saliva - biochemistry Flashcards

1
Q

what things happen in the oral cavity that saliva is involved in

A

EVERYTHING

1) diseases of soft and calcified hard tissues
2) Interactions between oral cavity and restorative procedures + materials AND prostheses + prosthetic materials
3) role in surgical procedures and wound healing
4) Interactions with food and oral therapeutics

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2
Q

what is resting saliva

A

when salivary flow NOT being stimulated (by smells, eating, chewing, swallowing)

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3
Q

what does salivary volume differ between

A

males and females

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4
Q

what range is normal daily saliva secretion

A

0.5 - 1.5 litres

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5
Q

what is flow rate of unstimulated saliva per minute

A

0.3-0.4ml

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6
Q

what does flow rate of unstimulated saliva per minute change to during…

a) sleep
b) stimulating activities (smells, eating, chewing, swallowing)

A

a) 0.1ml

b) 4ml (0-5)

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7
Q

list the 3 major salivary gland pairs, their makeup and what %s they contribute

A

parotid = serous, 20% of resting, 50-60% stimulated

submandibular = seromucin, 65% resting

sublingual = mucous, 5-7% resting

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8
Q

where do the minor salivary glands exist and what %s do they contribute

A

in hundreds in the soft palate, buccal + labial mucosa and all over oral cavity
8-10% of resting

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9
Q

what is gingival crevicular fluid exudate (GCF)

A
  • comes from major and minor glands
  • secreted into + contributes to composition of saliva
  • collects in gingival crevice and pockets
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10
Q

what do relative contributions from salivary glands vary with

A

1) time of day
2) age
3) health status
4) medication
5) flow rate (circadian rythm; stimulus’ nature)

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11
Q

what is the result of chemical stimulation on the contribution from different salivary glands when compared to resting

A

parotid = 20% resting, increases to 50-60% after stimulation

submandibular = 65% at BOTH resting and after chemical stimulation

sublingual = lowest contribution, resting contribution more than stimulated

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12
Q

what is the result of sialogogues (drugs promoting saliva secretion) on salivary flow rate using

a) NaCl
b) Sucrose

A

sucrose (0.9ml at 1 mole) stimulates salivary flow BUT less than NaCl (1.5ml at 1 mole)

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13
Q

what is the most potent stimulus of salivation

A

acid

ie citrus fruit / fruit juices

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14
Q

what does the circadian rhythm curve (24 hr period) tell us about salivary flow rates

A
  • lowest during sleep

- highest at midday and late aft (6pm)

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15
Q

what are the 2 main categories of function of saliva, explain these

A

1) mechanical
- lubrication (of mucosa, food bolus during swallowing, of oral cavity for speech)
- dissolve food (helps it reach tastebuds for taste and wash it away for new taste)

2) chemical
- protective buffering (remin so anti-carious, due to Ca^2+ , [PO ₄]³⁻ and HCO3^-)
- antimicrobial
- protection + repair (due to growth factors and salivary proteins)

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16
Q

which antimicrobials are contained in saliva

A

1) lysozyme
2) immunoglobulins
3) lactoferrin
4) complement factors
(also self-defence peptides + salivary proteins)

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17
Q

how is saliva able to protect hard tissues

A
  • buffer content
  • HCO3^- = maintains salivary pH
  • F- = replace Ca2+ in HAP (strengthens teeth)
  • pellicle proteins = 2 types of pellicle
    1) mucosal - protects mucosa
    2) acquired enamel - protects hard tissue (teeth)
  • pH rising factors (sialin)
  • Ca^2+ + [PO ₄]³⁻ = maintain mineral content of teeth
  • antibacterial factors
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18
Q

how is saliva able to protect soft tissues

A
  • growth factors = help it heal in ulcer / injuries

- lactoperoxidase = antibacterial role

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19
Q

what are the 7 protective functions of saliva

A

1) airway maintenance
2) speech
3) eating, swallowing, mastication
4) control of bacteria, fungi
5) digestion / GIT
6) protection / repair of oral mucosa
7) protection / repair of dentition

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20
Q

what is the protective mechanism for airway maintenance

A
  • antibacterials
  • water retaining glycoproteins - play an agglutination role (stick to bacteria, aggluting them, prevents them attaching to tissues of oral mucosa and airway of mouth) also maintain moisture of oral mucosa and airways
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21
Q

what clinical problems occur in airway maintenance because of lack of saliva

A
  • increased air-borne microorganisms in airway

- dehydration

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22
Q

what is the protective mechanism for speech

A

lubrication

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23
Q

what clinical problems occur due in speech because of lack of saliva

A
  • dehydration

- difficulty of speech

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24
Q

what is the protective mechanism for eating, swallowing, mastication

A

(aids in this function because of 2 effects)

1) antibacterials
2) lubrication

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25
Q

what clinical problems occur due in eating, swallowing, mastication because of lack of saliva

A
  • food-borne microorganisms
  • abrasion of oral mucosa and ulceration (by debris or large food)
  • due to lack of lubrication of food + lack of formation of food bolus
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26
Q

what is the protective mechanism for control of bacteria, fungi (the antimicrobial effect)

A
  • antibacterials
  • immunoglobulins (esp IgA)
  • lactoferrin
  • histidine
  • lysozyme (bactericidal - degrades bacterial cell wall by piercing it)
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27
Q

what is the role of immunoglobulin A (IgA) in control of bacteria, fungi

A

antiviral, antibacterial, attaches with glycoproteins and when secreted helps agglutination of bacteria to inhibit it attaching to mucosa or tooth surface
then the bacteria is swallowed and killed by gastric acid

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28
Q

what is the role of lactoferrin in control of bacteria, fungi

A
  • enzyme containing iron
  • needs iron for its function
  • takes on all iron in environment
  • bacteriocidal effect
  • bacteria need iron to grow (prevents growth + multiplication of facultative + aerobic bacteria depriving them of the iron needed for O2 transport)
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29
Q

what is the role of histidine in control of bacteria, fungi

A
  • salivay protein
  • a self defense peptide = potent antimicrobial effects
  • exist in saliva and other bodily fluids
  • ie deficins, histatin 1,3,5 and stetherin
  • histatin 3 = antifungal and antiopportunistic infection
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30
Q

what clinical problems occur due in control of bacteria, fungi because of lack of saliva

A
  • infection rate increased

- maintenance of commensals affected

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31
Q

what is the protective mechanism for digestion/GIT

A
  • amylase = starts carbohydrate digestion in mouth but minimal effect, stops once reaches stomach (acidic)
  • specific antibacterial effect
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32
Q

what clinical problems occur due in digestion/GIT because of lack of saliva

A

NONE

  • digestion not affected
  • mouth only accounts for 17% of carb digestion
  • rest = small intestine
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33
Q

what is the protective mechanism for protection / repair of oral mucosa

A
  • mucin film (mucosal pellicle) = covers oral mucosa, helps lubrication + inhibition of microbial attachment to it. made up of salivary proteins (mustin, histitin, statherin)
  • growth factors
    1) epidermal growth factor EGF = repairs epithelial tissues and starts their regeneration = prevents + heals apthous ulcers + wounds
    2) vascular growth factor = repair mucosa after ulceration / abrasion and protective effect against toxins, carcinogens etc
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34
Q

what clinical problems occur due in protection / repair of oral mucosa because of lack of saliva

A
  • toxins, carcinogenesis

- cause tissue damage and non-healing ulcers

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35
Q

what is the protective mechanism for protection / repair of dentition

A
  • Ca^2+, [PO ₄]³⁻ = maintain mineralised tooth tissue
  • HCO3^- = raises acidic ph, maintains pH thus remineralisation
  • pellicle protein (histatin 3 and stetherin)
  • F- = replaces Ca2+ in HAP if enters tooth surface, calcium hydroxide becomes fluoride hydroxide (stronger mineral formation + crystals) so anticarious
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36
Q

which pellicle aids protection / repair of dentition and how

A

acquired enamel pellicle (transparent membrane)

1) forms within 5 minutes of cleaning teeth
2) made of mainly salivary proteins (esp histitin 3 + stetherin) = maintain Ca^2+ , PO4^3-, inside the tooth surface protecting it
3) directs plaque forming bacteria to allow only favourable (NOT carcinogenic bacteria)

37
Q

what is the clinical significance of the acquired enamel pellicle in composite or resin fillings

A
  • enamel surface acid etched to make micropores that hold the restoration
  • have to keep enamel dry (not in contact with saliva) before restoration placed to ensure pellicle is NOT formed (would close the micropores, resin cant properly attach, restoration fails)
38
Q

what clinical problems occur due in protection / repair of dentition because of lack of saliva

A

increased incidence of

  • caries
  • periodontal disease
  • erosion
39
Q

how is oesophogeal mucosa repaired and healed and why may this be necessary

A
  • by external and vascular growth factors in saliva

- damage may be caused to it in people who vomit a lot (GORD, acid reflux, bulimia)

40
Q

what is the name for the condition of dry mouth

A

xerostomia

41
Q

when is saliva considered to be absent / extremely lacking

A

if flow rate decreases to 0.1ml/min or less

42
Q

list 9 clinical consequences of xerostomia

A

1) rapid destruction of teeth and gums
2) mucosal damage
3) glossitis (cracking of tongue)
4) candida infections (oral thrush - glossitis makes good environment for its growth)
5) taste problems
6) difficulties with mastication, swallowing, speech
7) rampant caries
8) periodontal disease
9) cracked lips

43
Q

how does glossitis appear and what does it cause

A
  • inflamed, cracked tongue

- contributes to infection - cracks harbour fungus or bacteria leading to halitosis

44
Q

what are rampant caries, where can they be most dangerous

A
  • rapidly progressing caries (produce rapid damage to teeth)

- v detrimental to dentition in people who also have high caries index

45
Q

what are local causes of xerostomia

A

1) sialolithiasis
2) salivary gland tumour
3) sialadentitis

46
Q

what are systemic causes of xerostomia

A

1) sjogrens syndrome (SS)
2) medication
3) cancer therapies
4) undiagnosed / uncontrolled diabetes
5) neurological conditions (bells palsy, cerebral palsy, trauma)
6) sialotrophic infections (Hep C, HIV)

47
Q

local causes

what is sialolithiasis and how does it cause xerostomia

A
  • stones of the salivary ducts
  • highest incidence in submandibular gland (duct runs horizontally so not affected by gravity)
  • 2nd highest in parotid
  • can block the salivary duct preventing saliva secretion
48
Q

local causes

what are give an example of a salivary gland tumor, and how do they cause xerostomia

A
  • pleomorphic adenoma (benign, large, mostly in parotid gland)
  • cause blockage as it pressurises the duct preventing saliva secretion
49
Q

local causes

what is sialodentitis and how does it cause xerostomia

A
  • infections (viral OR bacterial) of the salivary gland itself (NOT the ducts) which can affect salivary flow
50
Q

what is sjogrens syndrome (SS)

A
  • autoimmune disease
  • leads to parotid and submandibular gland dysfunction as the body cannot recognise its own tissue
  • SO parotid and submandibular acini recognised as foreign tissue
  • theyre attacked by immune system, infiltrated with lymphocytes and acini completely destroyed (so no longer produce saliva)
51
Q

what are the two types of sjogrens syndrome and who does it affect most

A 
primary = NOT associated with other autoimmune disease
secondary = associated with other autoimmune disease (rheumatoid arthritis, lupus)

prevalent in females aged 40-60 (1 in 2500 women)

52
Q

where else does sjogrens disease cause dryness

A

the eyes

affects lacrimal glands

53
Q

how many types of drugs can cause xerostomia and what are these mostly categorised as

A

OVER 500!

  • anti-parasympathetic
  • anti-cholinergic
54
Q

where is medication causing xerostomia most important and dangerous

A

elderly patients

  • complex medications
  • synergistic affects when taking multiple medications raises incidence of xerostomia
55
Q

why is parotid salivary gland most highly sensitive to radiation therapy used to treat oral carcinomas

A
  • serous acinar cells = more sensitive than mucous cell types
  • serous contain more heavy metal ions - absorb radiation energy promoting free radical release
  • free radicals destroy the salivary glands of salivary ducts so destroy serous acini
56
Q

what is the issue with xerostomia produced by radiation therapy

A

MOSTLY IRREVERSIBLE

  • rarely recovers completely
  • in some cases = reversible within 18 months and some recovery in first year
  • if treatment 60+ rays = definitely irreversible (as little as 10 can be too)
  • after 5 weeks of radiation = salivary flow greatly reduced
57
Q

when doing radiation therapy what should we do if possible

A

spare a portion of the parotid gland from radiation

58
Q

what increases to compensate for radiation damage

A

salivary flow from contralateral glands

59
Q

what is important for residual lubrication following radiation damage

A

recovery of mucous glands (less radiosensitive than serous glands)

60
Q

what changes are present after radiation therapy

A
  • saliva more viscous
  • saliva yellow-brown colour
  • salivary buffering capacity reduced so pH decreases
  • antimicrobial activities compromised
  • increased incidence of oral disease
61
Q

what drug can be given to patients undergoing radiation therapy that includes a significant portion of the parotid glands to reduce incidence of xerostomia
how does it work

A

AMIFOSTINE

  • chemoprotective
  • scavenger of free radicals
62
Q

what does chemotherapy cause and result in

A
  • systemic immunosuppression which affects salivary immunoglobulin content exacerbating the effects of a dry mouth
  • this results in oral mucositis, progression of gingival disease, caries, opportunistic infection
63
Q

which types of chemotherapeutic drugs cause xerostomia and how

A

antineoplastic drugs - degree of xerostomia caused is related to the total number of chemotherapeutic agents used
- we DO NOT know exact mechanism by which they damage tissue

64
Q

what is observed in chemotherapy patients with low flow rates

A
  • increased salivary drug concentration

- prolonged contact of drug containing saliva with oral epithelium

65
Q

what does high concentration of a biologically active drug result in

A

increased toxicity to oral tissues

66
Q

why is amifostine used

A

detoxifies reactive metabolites of cisplatin (cancer drug)

67
Q

how does diabetes cause xerostomia

A
  • xerostomia + freq urination = 1st symptom of it
  • HBA1C inversely proportional to salivary flow SO more blood glucose attached to haemoglobin = lower salivary flow (reported in type 2)
  • type 1 = fasting blood sugar levels
68
Q

how do neurological conditions cause xerostomia

A

affect neurological parasympathetic stimulation / control of salivary flow

69
Q

how do sialotrophic infections cause xerostomia

A
  • lead to autoimmune disease of salivary glands as infected cells become foreign
  • causes sjogren-like syndrome
70
Q

what causes parasympathetic outflow and what does it result in, how does this increase flow of watery saliva

A
  • coordinated via centres in the medulla, innervation occurs via facial + glossopharyngeal nerves when afferent info from mouth is sent to brain
  • release of acetylcholine (ACh) onto M3 muscarinic receptors
    causing…
  • acinar cells inc saliva secretion
  • duct cells inc HCO3^- secretion
  • co-transmitters cause inc’d blood flow to salivary glands
  • myoepithelium contracts to inc rate of saliva expulsion
    SO incd flow of saliva more watery in composition
71
Q

what 4 methods are used to treat xerostomia and stimulate salivary flow

A

1) chewing sugar free gum or sweets
2) artificial salivary substitutes
3) water-based oral moisturising gels
4) medication

72
Q

how does chewing sugar free gum or sucking sweets stimulate saliva

what else may help increase salivary flow in ss patients

A
  • gum = mechanical stimulation
  • sweets = chemical (gustatory) stimulation - esp if use citrus lozengers (vitamin c, lemon drops) but w caution due to its acidity

sonic toothbrushing

73
Q

how do artificial salivary substitutes (ie oralube, xero-lube) help stimulate saliva

A
  • short term relief
  • common
  • unpleasant SO low compliance - contain carboxymethylcellulose (mimics viscosity of natural saliva)
74
Q

how do water-based oral moisturising gels help stimulate saliva

A
  • used intraorally as a saliva substitute

- used extraorally on lips to provide 8 hours of relief from symptoms

75
Q

what is the medication used to increase serous secretion, give 2 examples

A
  • cholinergic agonists which provide parasympathetic stimulation of exocrine glands
  • PILOCARPINE (h+n cancer and ss pts)
  • CEVIMELINE (ss pts)
  • both fda approved
76
Q

what is the problem with the cholinergic effect of these drugs clinically
where may this be of benefit

A
  • systemic so affect ALL exocrine glands
  • adverse effects (ie excessive sweating)
  • SO use with caution in patients with cardiovascular disease, chronic respiratory conditions, kidney disease

relieving multiple symptoms of ss

77
Q

in which patients is the use of these cholinergic systemic drugs contraindicated

A
  • narrow angle glaucoma
  • uncontrolled asthma
  • liver disease
78
Q

what is current research on xerostomia treatment investigating

A
  • using other medication classes that may relieve dry mouth symptoms
  • tissue engineering and regeneration technology
  • salivary transplantation
79
Q

why is the oral cavity considered to be compartmentalised

A
  • positioning of major glands

- oral conformation

80
Q

what is the result of where the salivary glands are situated in the oral cavity + where their ducts open

A
  • site specific retention and clearance (some areas retain food, debris, drugs more than others)
  • limited transfer across mouth
81
Q

what has leeds research discovered about salivary retention of fluoride (15 minutes after rinsing with 1000ppm F mouthwash)

A
  • upper labial sulcus retains more than lower
  • upper labial sulcus on RIGHT = highest retention
  • posterior lhs + rhs = comparable, less retention
  • least retention in the tongue (due to its movement)
  • retention higher in upper, clearing higher in lower
82
Q

research
what was measured after a patient wore a retainer containing some sterilised dentine particles for a period and then dissolved a fluoride tablet on upper right sulcus
fluoride retained in dentine particles measured

A
  • RHS shows highest retention until 30 minutes

- LHS much lower retention over time

83
Q

how does different compartments of the oral cavity having different retention and clearance have clinical relevance

A

1) retention / clearance of sugars (areas retaining more = higher caries incidence)
2) areas retaining fluoride + therapeutics equally = respond to therapy better
3) areas retaining toxins / carcinogens more = damaged more
4) slow-release devices like ionomers (knowing how compartmentalisation works helps)

84
Q

why do we analyse saliva

A

contains many marker of health + disease so analysing helps understand more about them

85
Q

what do we need to know and control in order to analyse saliva for experiments

A
  • nature of sample (from fixed or single gland)

control

1) time of day sampled
2) flow rate
3) nature of stimulant if used

  • understand the method of collection (paper points, curby cup, cannulation, drooling)
86
Q

how is site specific sampling using paper points carried out and what is this best for

A

1) weigh filter paper point prior to experiment
2) put it in labial sulcus to collect saliva from minor salivary glands
3) then weigh it after to find weight of saliva
4) put paper point into eppendorf tube
5) analyse nucleic acids
6) can extract proteins and buffers from the sample

BEST WAY FOR collecting saliva from minor salivary glands

87
Q

how is collection carried out using curby cup and what is this specific for

A

1) inner chamber fits over parotid gland
2) outer chamber holds device in place through gentle suction applied by syringe attached to a tube
3) inner chamber exerts squeezing so parotid gland produces saliva
4) saliva collected from inner chamber via exit tube

SPECIFIC FOR collection of parotid saliva (collect single saliva from a single gland)

88
Q

immediate analysis of saliva preferred - what are the consequences of freezing

A

1) loss of enzyme activity (denatured)
2) loss of CO2 by diffusion
3) pH changes
4) desquamated cells in saliva will be lysed on freezing
5) freeze-drying causes irreversible protein precipitation

IOE (22 decks)

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