Oral Biology: Biofilm Microbiology

• The notes contain information on oral biology and cariology.

Week 1: Microbiology

• Biofilm: a layer of microorganisms attached to a surface, encased in a self-produced slime layer of polysaccharides, DNA, proteins, and lipids.
• Biomass: the mass of microorganisms in the biofilm
• Extracellular Polymeric Substance (EPS): slime layer created by biofilm, can be confused with the extracellular polysaccharides formed by S. mutans
• Microbic growth is not possible, and biofilm formation is impossible without water.
• The extracellular matrix protects microorganisms from removal and antimicrobial agents.
• Water channels in biofilms allow nutrients and oxygen to reach deeper layers.
• Environmental changes can alter the phenotype of the biofilm by switching genes on or off, affecting behavior and appearance.
• Example: Microorganisms entering a biofilm may lose flagella.
• Aggregates: clusters of microorganisms.
• Early colonizers are bacteria that attach first and can grow in the initial biofilm phase.
• Late proliferators are bacteria that attach to the pellicle first but grow later, often anaerobic.

Biofilm Formation Stages

• Microorganisms attach only to surfaces with a conditioning layer, or pellicle, made mainly of proteins from saliva and crevicular fluid.

Initial Adhesion

• Microorganisms are attracted by electrostatic forces; attachment may or may not occur (5-10 seconds).

Definitive Adhesion

• Microorganisms anchor to the pellicle's proteins via receptors.
• Biofilms can clump together (co-aggregation) during growth.

Maturation

• A large slime layer (extracellular matrix) forms
• Microorganisms detach and are often removed by oral microbiota, swallowed in saliva.

Biofilm Succession

• Ecosystem species composition evolves, creating a complex, stable ecosystem.
• Mechanical cleaning removes half of the plaque, starting a new ecological succession.
• Biofilm redevelops in stages, with F. nucleatum playing a key role by linking early and late colonizers.
• Biofilm succession stops when brushing restarts.

Cariës Formation Factors

• Pellicle layer allows oral micro-organisms to stick to enamel
• Saliva removes micro-organisms through its flow, buffers, and contains nutrients and antimicrobial peptides.
• White blood cells and signaling molecules in saliva fight pathogens, but immune factors do not have a big part in caries growth
• Behavior has a big part in caries growth, the frequency of Eating habit, sugar intake, and brushing habits
• More than 6-8 eating periods per day leads to higher likelihood of caries as pH reduce below 5.5, leads to demineralization, the more frequency in eating the more often demineralization occur.

Cariës

• Cariës is not caused by a single micro-organism, but several acid-producing organisms and host factors.
• Anaerobic bacteria, such as lactic acid bacteria, are mainly attached to the tooth side of the biofilm, producing lactic acid from any sugar source, at different rates depending on the source.
• Sucrose metabolizes rapidly, causing a quick pH drop, whereas lactate and starch metabolize slower, causing less caries.
• All lactic acid bacteria are cariogenic, but S. mutans is the most

Stephan Curve

• Rapid metabolism of sugar causes pH to drop faster than saliva buffer
• Microorganisms that use lactate as food (Veilonella) produce less cariogenic acids
• Balance between remineralization and demineralization exists in a healthy mouth, with rapid acid neutralization by saliva in patients with high caries activity.
• Demineralization happens at the enamel surface, while remineralization happens in biofilm, and then in enamel surface.

Ecological Plaque Hypothesis

• Dysbiosis of oral microbia causes pathogenic bacteria to take over.
• Sugar intake can cause tooth-demineralization by reducing pH,
• Micro-organisms able to live in low pH gain advantage and cause caries, which consists of lactobacilli and various streptococci.
• Commensal bacteria struggle to survive in acidic environment.

Cariogenic Bacteria

• Lactobacilli and Mutans streptococci causes caries most frequently
• Acidogenic : High Acidity output
• Aciduric: low pH survivality (better handle intracellular pH)
• EPS Formation and IPS Formation are virulence factors of mutans streptococci

Prevention

• Zuurvorming van bacteriën remmen door biofilm bloot te stellen aan 3-oxo-N.
• It has no effect on the growth of micro-organisms/plaque, but it does have an effect on the lactate production.
• Arginine: is metabolized by microbiota to ammonium (NH3) this base can bind H⁺ ions, which increases the pH.

Week 2 - Biochemistry

• These notes contain information on the nature of saliva, and the different parts of saliva producing glands.
• Acini, or lobes of salivary glands, consists of secretous cells.
• Sereuze Acini: Watery saliva secreters, are grain-shaped due to protein granules.
• Muceuze Acini: Viscous saliva secretors which attract water which leads to cell nuclei being pushed aside and more volume within
• Seromuceuze Acini - in human mouth see photo a. In Histology photo b
• During histological examination, muceuze cells get damaged due to mucous attracting water and swelling the cells. The nearby sereuze cells then get pushed aside, creating cells in a half-moon shape
• Apical membrane of Acinaire cells contain “Aquaporines” for fast water transport between interstitium and lumen.
• Acini en the cells in the drain system also contain “Myo-Epitheelcelen”, for contracting and quicker movement of Saliva.
• Note that the interstitium are the space around cells.

Salivary Glands

• Salivary glands come in three groups: The Parotis, GL. Submandibularis, and Gl. Sublingual is
• Parotis is active when consuming sour foods or chewing. GL Submandibularis is used for resting or sleeping and activity when sour chewed. GL. Sublingualis is used for sleep.
• There also exists small accessoire cel-glands to secret saliva - The palate, the lip, the cheek and the tongue.
• Acini are either Sereuze, Seromuceuze, or Muceuze.

The various properties of saliva include

• Watery saliva has Sereuze acini properties
• Viscoelastic saliva has seromuceuze. The mouth saliva from submandibular and sublingual glands mix, the result means collecting and testing the mixture.

Regulation of salivary secretion

• Salivary glands are innervated by double nerves.
• Sympathetic activation increased protein contents in saliva, noradrenaline hormone activates the enzyme adenylcyclase to create C-AMP
• parasympathetic activation increased water in saliva, the sodium-kalium pumps move more natrium from the cell out, into the cell more kalium come on, this cause a gradiënt , co-transport all 3 elements inside the cell, the water and ions form liquid
• nerve stimulaties with calcium increases , the ions channels are opened and osmotic preassure rises for water to go to lumen

Control of salivary secretion

• Stimuli cause saliva flows when: Chewing, feeling smell and tast
• Salivary suppressants: medicine usages(polyfarmacy), infection at the glands of Sjögren, being a head area rays victim, stress
• Water Balance and Nerve Stimulation are also causes
• The Primary Saliva consists off a liquid that was separate by Acini cells, the saliva ions consist out of bloodplamsa
• Transporters are used to pull back into the body ions, which leaves the final concentration in saliva low.

The following correlations can be used for salivary secretion:

• Higher flow rate/secretion rate reduces ions being pulled back into the body, which gives a higher ion concentration (happens when eating, hco3 is ready to buffer food)
• Higher secretion rate, lower the eiwit and mucine concetrations
• Total mount of eiwit and mucine reduces t.o , rust , however due to bigger mouth now its more saliva
• In creviculaire vloeistof / connection to the interleukal are increase concetration of eiwit of serumalbumine and antibodies .

Week 3 – Mucinen en de functie van saliva

• Information presented is about mucinen.
• The most common salivary proteins are amylase and mucinen. Mucinen are a polyeptide string with carbohydrate zijtakken
• Great amount of side branches in mucus protect against eiwitsplitsende enzymes and denutariatie upon pH
• Muc5B and Muc7 are types of mucus in saliva. The following characterics can be described to Muc5B
• the chains are long, can interlock due to zwavelbruggen which contain aminozuur molecules.
• A large koolhydraatzijketen with negativity charged and collect waters
• Are forced into a gestrekte formatie
• In the Aciunus this substance is in blaasjes form, which contain calcium to prop negativiteit sidechains. Upon fusing with the lumen, calcio will be switched with natrium.

Week 4 cariologie + radiologie

HC1 Cariologie: etiologie

• In Keyes circle multifactoritiële is presented from caries Sociodemographic Status - Education, Income Saliva - Buffer capacity, composition, Flow Rate Antibacterial agent - protein Tooth Diet - amount, composition , frequency Time - Dental sealants, Sugars, Dental coverage, Clearance rate, Frequency Behavior