Week2 Flashcards
Global burden of Caries?
Nearly half (3.58 billion people worldwide) of the Worlds population is affected by some oral disease and Dental caries is one of the most prevalent!
Average saliva production in Adults and Kids?
- The average child produces between 0.5 and 2 L of saliva everyday
- The average adult produces between 0.5 and 1.5 L of saliva everyday
Antimicrobial components of saliva and their function to inhibit bacteria (5)?
- Lysozyme - Lysozyme digests the cell walls of Gram-positive bacteria by breaking the β(1-4) bond between N-acetylmuramic acid and N-acetylglucosamine (NAM-NAG) in peptidoglycan.
- Lactoferrin - Inhibits bacterial growth by binding and sequestering Fe2+ ions.
- Histatins – Results in cell cycle arrest and the cells lose ATP by efflux.
- Peroxidase – Oxidizer that inhibits bacterial metabolism.
- Secretory IgA - Agglutination
What is agglutination?
Clumping and adhesion of bacteria together. The majority of agglutinated bacteria is swallowed.
What results in “fixed” agglutination?
Immobilized S-IgA/ mucins embedded in the acquired pellicle
Two major salivary agglutinins discussed?
S-IgA and Mucins
What is S-IgA?
Secretory Immunoglobulin A
A binding protein that blocks receptors on epithelial cells to protect them as well as binds to bacteria to neutralize them.
- Dimeric IgA
- Joining (J) chain
- Secretory component (Facilitates trans-cellular transportation)
What are Salivary Mucins?
Principle component of mucus.
They provide a protective coating to mucus membranes, trap bacteria and contribute to pellicle.
Polypeptide backbone
Serine, Threonine, Proline rich domains
Oligosaccharide chains
Glucose, galactose, fructose, mannose
Difference between salivary pellicle and acquired pellicle?
When the salivary pellicle coats a hard surface, such as teeth, it is referred to as an acquired pellicle.
3 virulence factors of Streptococcus mutans ?
Adhesion- stick to teeth
Acidogenicity- make the environment acidic
Aciduricity- live in acidic environment
What contributes to adhesion in S. mutans?
(Glucosyltransferase (GTF)/ Fructosyltransferase (FTF))- Glycosyltransferases and Fructosyltransferases facilitate EPS formation.
EPS- extracellular polysaccharides which is important for colonization during plaque formation
What contributes to Acidogenicity in S. mutans?
Glycolytic Fermentation to make Lactic acid (under anaerobic conditions, glycolysis produces lactic acid)
Lactic acid is one of the strongest of all acids
What contributes to Aciduricity in S. mutans?
- F1/F0 ATPase to pump protons out.
- Change membrane to be tighter by saturation of fatty acids in it.
- Conversion of Agmatine to Putrescine, ammonia and CO2.
- Malolactic Acid fermentation
- Up-regulation of chaperones, proteases and DNA repair enzymes to help them deal with the acid.
Critical pH for Hydroxyapatite and HA content in enamel and dentin?
Enamel HA 98%- 5.5 pH
Dentin HA 70%- 6.5 pH
Critical pH for Fluorapatite?
FA- 4.5
What packs tighter into enamel? HA or FA?
FA
Why does FA drive remineralization at a lower pH?
Fluoride ion is more electro-negative than the hydroxyl ion
What can exacerbate demineralization of dentin?
Matrix-metalloproteinases (MMP’s) which are activated by lower pH’s- MMP’s are found in dentin and saliva.
Major target of Fluoride in bacteria?
It inhibits ATR mechanisms aka Ways to deal with acid and acid damage inside a cell.
- Arginine Deiminase System (ADS)
- Ammonia Synthesis
- F0F1 ATPase
ATR= Ataxia Telangiectasia and Rad3-related protein (ATR)- DNA Repair issues
Targets of SDF?
- Has both antimicrobial effects from silver and protective effects of fluoride
- Soluble in ammonia, can then be applied as a liquid
- Metallic silver is inert and low toxicity in humans
- Generates a phosphate reservoir by forming silver phosphate (Ag3PO4)
- High concentration of fluoride again helps generate fluorohydroxyapatite (FHA)
- Silver can disrupt Peptidoglycan cell walls, lyse cell membranes, denature ribosomes, bind DNA
SDF Zombie Effect?
Bacteria that are killed by SDF further act as a carrier for silver ions, DNA that is bound to silver is taken up by other bacteria, which is lethal to other bacteria that come in contact with it.
Target of Xylitol in S. mutans?
- Xylitol directly inhibits DexA
- Poor biofilm forming by S. m.
- Reduced Acid production
Xylitol mechanism in Streptococcus mutans?
- DexA breaks down Dextran which is a complex class of branched glucans
- This plays a role in the normal activity of glucosyltransferases and glycosyltransferases efficiency ie they don’t have sugars that are broken down to use and bacteria end up sugar starved and can’t make biofilm and acid.
Target of Epigallocatechin gallate (EGCG) a type of catechin and mechanism in Streptococcus mutans?
- Competes for binding on the salivary pellicle
- Inhibit normal function of glucosyltransferases so they can’t make glucans to store sugars and help with the matrix formation.
- gtf (B,C,D)
- Alter bacterial cell walls and/or cell membrane
What are the four modes of transmission highlighted in the lecture recording? Provide an example of each?
Direct- Contact with blood or body fluids
Indirect- Contact with a contaminated instrument
Droplets- Contact of mucosa of eyes, nose, mouth with droplets or spatter
Aerosol- Inhalation of airborne pathogens
What is the chain of infection starting with the source?
- Pathogenic Source
- Reservoir
- Mode of transmission
- Portal of Entry
- Susceptible Host
What are the four blood-borne viruses highlighted in the lecture recording?
- Hep B (HBV)
- Hep C (HCV)
- Hep D (associated with Hep B)
- HIV
What has the highest risk of infection resulting from a needle stick from an infected patient?
Hep B (1-62%)
Is saliva considered to be potentially infectious?
Yes- one droplet may contain up to 50K bacterium or virus belonging to more than 25 genres.
- What pathogens are of concern to dentists?
Bacteria-
TB
Gram neg Legionella
Strep pyogenesis
MRSA
N. Gonorrhea
Syphilis (Treponema Pallidum)
Viruses-
Cytomegalovirus (CMV)
Herpes 1 & 2
Respiratory Viruses
What is the most common mode of pathogen transmission in a healthcare setting?
Via the hands
At what concentration of alcohol does an alcohol-based hand rub need to be in order to be considered an effective disinfectant?
60-90%
What are the three reasons that gloves are worn?
- Minimize risk to healthcare personnel of acquiring infection from patients
- Prevent microbial flora from being transferred from healthcare personnel to patients
- Reduce contamination from one patient to another
Do you have to wash your hands if you wear gloves? Why or Why not?
YES!! Microtears or punctures
What is the difference between disinfection and sterilization?
- Sterilization is the process that kills or removes ALL organisms and their spores in a material or an object.
- Disinfection is the process that kills or removes pathogenic organisms in a material or an object excluding bacterial spores, so that they pose no threat of infection.
- Antisepsis is the application of a chemical agent externally on a live surface (skin or mucosa) to destroy organisms or to inhibit their growth.
What are the three methods of sterilization highlighted in the lecture?
- Heat
- Radiation
- Chemicals
What are the two types of disinfection highlighted in the lecture?
Physical and Chemical
Types of physical disinfection?
- Filtration- Pore size filters 0.22–0.45 μm remove most bacteria and fungi
- Ultraviolet (UV)- control of airborne contamination or to disinfect surfaces
- Laser- light Nd:YAG, Er:YAG, Er,Cr:YSGG, diode and KTP lasers can be used for photothermal disinfection
- Ultrasound and sound Ultrasonic (and upper audible) waves- frequencies greater than 20 kHz will kill microorganisms, cavitation which collapse violently and physically disrupt cell structures
Types of chemical disinfection?
- Alcohols- Most effective in aqueous solution (70%), Inactive against spores and some viruses
- Aldehydes- Glutaraldehyde: Alkylating agent, High potency disinfectant, toxic
- Biguanides- Chlorhexidine: Surgical scrub 0.4%, Plaque control 0.2%, Dentures 2%
- Phenol-based compounds: (Triclosan, Lysol and chloroxylenol(Dettol)): disrupting lipid containing membranes, Inactive against spores and viruses
- Halogen-based compounds: Iodine or chlorine (Wescodyne and Betadine)
- Surfactants: Detergents: attacks lipid by layer, Inactive against viruses and spores
- Oxidizing agents: Hydrogen peroxide, Inactive against viruses, spores, some bacteria
- Heavy metals: Mercury, silver, Inactive against spores, Toxic to humans
What are the three classes of dental instruments? Provide an example of each.
- Critical- penetrates tissue or bone: scalers
- Semi-critical- Contacts mucus membranes: mirrors
- Noncritical- Contacts intact skin: blood pressure cuff or x-ray head
What is the risk of having a biofilm established in water lines used for dental treatment?
High- having a pathogen infect someone is less but it does happen- higher risk for high risk populations
Where do these bacteria often originate from?
- Water source: environmental organisms -harmless in immunocompetent individuals
- Backflow from dental apparatus “suck back”: opportunistic respiratory pathogens ( such as Pseudomonas aeruginosa, mycobacteria, Legionella) and oral bacteria
How might a dental office prevent biofilms in dental water lines?
- Flushed for 2 minutes at the beginning of each day and for 30 seconds between patients.
- Independent water reservoirs
- Chemical treatment
- Filtration
- Anti-retraction valves
- Sterile water delivery systems
- Water testing laboratory
- In-office testing with self-contained kits
- Follow recommendations provided by the manufacturer of the dental unit or waterline treatment product for monitoring water quality
Use sterile water for irrigating in surgical procedures
Why might a mouth rinse, such as chlorhexidine, be used prior to dental treatment?
- Reduce microorganisms in aerosols/spatter
- Reduce the number of micro-organisms introduced into the bloodstream
