Oral environment Flashcards
What do oral fluids contain
Saliva
-Major and minor salivary glands
Gingival crevicular fluid
Oral bacteria
Food debris
Epithelial cells
What are the functions of the oral fluids
Protective
-Cleansing
-Mucosal protection
-Buffering
-Remineralisation
-Antimicrobial
Digestive
-Taste
-Digestive enzymes
-Lubricates bolus for chewing, swallowing
How do the oral fluids provide mucosal protection
A dry mucosal surface is at a greater risk of infection
What is a symptom for patients with salivary gland disease
Xerostomia (dry mouth) lack of various protective components
What issues arise with reduced salivary flow
Increased incidences of dental caries
Caries present on buccal and labial surfaces
What type of glands are salivary glands
Exocrine
What are the major salivary glands
Parotid
Submandibular
Sublingual
Where can minor salivary glands be found
Buccal (mucous)
Labial (mucous)
Lingual (serous & mucous NOT MIXED)
Palatal (mucous)
What is the gingival crevicular (sulcular) fluid
Fluid from the epithelium lining the gingival crevice (sulcus)
What is the function of the Gingival Crevicular fluid
No ‘function’ as such but possibly acts as an Inflammatory exudate
When is GCF produced
There is little production from healthy gingivae, but flow increase with inflammation (gingivitis)
What is the daily salivary flow
Averages 500-700 ml
What glands contribute to the production of saliva
Parotid
Submandibular
Sublingual
Minor glands
When sleeping what is the percentage makeup of saliva by the different glands
Parotid - 0
Submandibular - 70%
Sublingual - 15%
Minor glands - 15%
What is the difference between the makeup of saliva from glands when resting and stimulated
Parotid - 20% , 50%
Submandibular - 72%, 40%
Sublingual - 4%, 2%
Minor glands - 4%, 8%
What factors affect unstimulated salivary flow rate
State of hydration
Previous stimulation
Circadian rhythms
Circannual rhythms
Medications
Salivary gland disease
What is saliva composed of
Inorganic:
Water (99.5%)
Ions (0.2%)
Organic:
Mainly proteins (0.3%)
Little carbohydrate or lipid
When does greater bicarbonate ion conc of saliva occur
At greater flow rates as it is important for buffering plaque acids
What is the function of Fluoride in saliva
Antibacterial
Forms fluorapatite
Promotes remineralisation
Why is thiocyanate present in saliva
Antibacterial agent
What purpose do bicarbonate and phosphates play in saliva
Buffering properties to limit acidic attack
What can calcium and phosphate be used for within saliva
Remineralisation
What buffers are present within saliva
Bicarbonate: effective at high flow rates, when [HCO3] is highest
Phosphates: important ‘at rest’
Proteins: limited effect, as main buffering action occurs at pH <5
Bacterial NH3 : some role in buffering plaque acid
What are the balanced equations of the buffers within saliva
Bicarbonate
Phosphate
Ammonia
H20+CO2<–>H2CO3<–>H+ +HCO3-
H2PO4- <–> H+ + HPO4 (2-)
Urea ———-> CO2 + NH3
NH3 + H+ ——> NH4+
When is mucous secretion greatest
When sleeping (30%)
When is DNA most susceptible to radiation
When separated for translation and transcription to produce proteins
What is an example of previous stimulation
Chewing gum, eating etc
What natural body secretion can protect against radiation
Saliva
What are the main salivary proteins
Amylase
Cystatin
Gustin
Histatin
Immunoglobins
Lactoferrin
Lactoperoxidase
Lipase
Lysozyme
Mucoproteins
‘Plasma proteins’
Proline-rich proteins
Statherins
Where could amylase be found
Mucosal gland secretions
Saliva
What is the function of lysozyme
Attacks bonds in bacterial cell walls, causing lysis
Involved in antibacterial and immune functions found in body secretions
What property does lactoperoxidase have and why
Antimicrobial effect due to oxidation of thiocyanate
What do cystatins do
Inhibit cysteine proteases, especially in bacteria
Antimicrobial function
What drug will impact the effects of Gustin
Erectile disfunction drug
Impacts taste
What are histatins
Histidine rich proteins
Inhibit CaPO4 precipitation
Antimicrobial
Inhibits:
-candida albicans
-streptococcus mutans
What are immunoglobins
Antibodies
What protein binds Fe3+ and possesses antimicrobial properties (especially against bacteria that require Fe)
Lactoferrin
What secretes lipase
Von Ebner glands on tongue
What does lipase do
Hydrolyses triglycerides
(may assist in digestion of milk)
What is the purpose of mucoproteins
Bind to tooth and epithelial surfaces:
-protective role
-lubrication
-component of primary pellicle
Affects bacterial adhesion
Promotes bacterial aggregation - easier clearance from mouth
What proteins resist acid attack
decrease mineral loss
regulate bacterial attachment
Proline-rich proteins
What protein has anticalculus action
Statherins
What are plasma-derived substances
Proteins e.g. albumins
Blood group substances
Immunoglobins
Hormones
Drugs
Which salivary constituents have these functions:
(a) Antimicrobial
(b) Buffering
(c) Digestive
(d) Lubrication
(e) (Re)mineralising
(a)Histatins, amylase?, Lysozyme, Lactoperoxidase, cystatins
(b)Bicarbonate
(c)Lipase
(d)Lubrication
(e)Proline rich proteins
What are the mechanical and chemical unconditioned salivary stimuli
Mechanical
-pressure on PDL/oral mucosa
Chemical
-gustation
-olfaction
-common chemical sense
How does mechanical stimuli work
Pressure on PDL (chewing) causes an increase in flow from ipsilateral glands
What receptors and action brings about a gustation stimuli
Receptors on taste buds:
-tongue dorsum, palate and epiglottis
Different potencies (flavours)
-acid > umami > sweet > bitter
**adaption to constant stimulus
What is stimulated during olfaction stimuli
Receptors in olfactory epithelium
Produces very weak stimulus in humans
What is conditioned salivary stimuli
Learned responses to:
Psychic stimuli
Visual stimuli
Auditory stimuli
Requires regular enforcement to maintain responses
How does the PSNS respond to salivation
Increased secretions, increases blood flow via vasodilation
Where do the primary salivary secretions occur
Acinus
What does primary secretion depend on
Acetylcholine
Salivary secretion is a 2-stage mechanism what does the second stage involve
Reabsorption of sodium chloride
Secretion of potassium and bicarbonate
Is saliva hypotonic
yes
What volume of saliva is in the mouth
1.1ml (0.5-2.1ml)
Where is film flow of saliva highest
Lower lingual region
Where is saliva secretion slowest
Labial and buccal region
Where are cariogenic sugars retained longest
In regions when flow is lowest
What is clearance
The rate at which substances are removed from the mouth
Where are caries less frequent
Lingual region due to greater saliva retention/flow
What are important oral health aspects of clearance
Removal or ‘harmful’ materials
Retention of ‘beneficial’ materials
What are the steps in clearance
Stimulus
Salivary flow
Accumulation in mouth
Swallow trigger
Residual volume
What are some beneficial substances retained by slow clearance
Fluoride
Chlorhexidine
How is sucrose removed from the mouth
Rapid clearance, increased by high salivary flow
Why should fluoride preparations be tasteless and tablets should be sucked not chewed
Ensure slow clearance to retain more fluoride within the oral cavity increasing possibility of fluorapatite forming
What is a stephan curve
A graph of the plaque pH change over time
How does increased salivary flow neutralise plaque acid
Increased bicarbonate content of saliva
How does dilution of plague acid affect the oral cavity
Very little effect within plaque
What is the effect of chewing gum on saliva
Large initial increase in salivary flow rate
Flow subsides to just above normal flow
pH rises by 0.5 pH unit which persists for a long time
When is there a much larger increase in salivary pH when chewing gum
When the gum contains bicarbonate
Are the ‘sugar free gum aids oral health’ claims valid
Gum chewing does not remove plaque, but will increase salivary flow rate, although the increase is quite small
The salivary pH is increased
The stimulated saliva may promote remineralisation
What occurs below a pH of roughly 5.5
Demineralisation
Why are alternative ‘sugar free’ sweeteners better for oral health
Can not be metabolised to acids by plaque bacteria
What are examples of Bulk (cariogenic) sweeteners
Sucrose
Fructose
Glucose
Lactose
What are low caloric sweeteners
Mannitol
Sorbitol
Xylitol
What are some Non-caloric/high intensity sweeteners
Aspartame
Cyclamates
Saccharin
Sucralose
When will patients complain of Xerostomia
When salivary flow rates fall below 50% of normal levels
When will a reduction in flow to below 50% occur
As a result of loss of function of more than one major salivary
gland
What are causes of decreased salivary flow
Side effect of drugs
Radiotherapy
Diseases:
-Specific salivary gland disease
-Systemic diseases that also affect salivary glands (Sjogren’s syndrome)
-General conditions e.g. fluid/ electrolyte loss
How many drugs have decreased salivary flow as a side effect
> 400
Which caries are associated with reduced salivary flow
Smooth surface caries (anterior teeth)
What are the consequences of decreased salivary flow
Increased dental caries
Increase oral disease (stomatitis)
Dysesthesia
Impaired oral function
Diminished taste perception
What is Dysaesthesia
‘Burning’ mouth
Why are there consequences of decreased salivary flow
Decreased clearance leading to a loss of protective components such as:
-Antimicrobial agents
-Buffering
-Less remineralisation
-Mucins and other proteins
-Gustin
-Consumption of cariogenic confectionery in attempts to increase salivation
Questions to determine a diagnosis of Sjogren’s disease
‘Does your mouth feel dry when eating a meal’
‘Do you have difficulty swallowing any foods’
‘Do you sip liquids to help you to swallow dry foods’
‘Does the amount of saliva in your mouth seem too little’
What salivary substitutes can be used when no functioning gland tissue is present
Mucin based, cellulose based
(water alone is not very effective)
What drug can increase/stimulate salivary flow
Sialogogues - drug that promotes secretion of saliva
