Microbiology of the RC System Flashcards
describe the RCS
warm, moist and nutritious - lots of substrate - and has a variable but largely anaerobic climate
why is the RCS protected from the host defenses
due to lack of circulation in a diseased pulp
what is the anaerobic glove box technique and what did it find
many of the pathological bacteria found in the RC system are black pigmented anaerobic G rods
what are the black pigmented anaerobic G rods that are found int he RCS
- porphyromas sp
- prevotella nigrescens
- peptostreptococcus
- fusobacterium
- eubacterium
- actinomyces
what is the most common bacteria in endo infections
prevotella nigrescens
what do black pigmented anaerobic G rods release
lipopolysaccharides (LPS) AKA endotoxins
what do endotoxins cause
fever, collagenolysis, osteolysis
the canal walls/spaces are conducive to the formation of ____
biofilm
what are biofilms
complex, colonized communities of bacteria
what does biofilm adhere to
the root canal walls
what are the floating bacteria in the root canal system called
planktonic
which bacteria come out during root canal
planktonic and biofilm bacteria
how do we clean the isthmus
irrigating
what is the profression of RCS infections
- carious lesion or trauma opens tubules to bacterial invasion
- bacteria inflame pulp locally
- inflammation may overcome pulpal defenses and localized abscesses may form in coronal pulp
- infection increases in pulp and necrosis begins
- necrosis involves entire RCS
- infection uses portals of exit (apical foramen and lateral canals) to invade peri- radicular tissues (apical periodontitits)
- periradicular infection occurs beyond apex (apical abscess)
what 6 things must biofilm accomplish to cause disease within RCS
- MO must adhere to host surfaces
- obtain nutrients from the host
- multiply
- invade tissue
- overcome host defenses
- induce tissue damage
what is the definition of a biofilm
multicellular microbial community characterized by cells that are firmly attached to a surface and enmeshed in a self produced matrix of extra cellular polymeric substance (EPS) usually polysaccharide
what is the most common anaerobic gram - microorganisms in primary endodontic infections
porphyromonas
- prevotella
- peptostreptococcus
- streptococcus
-actinomyces
- olsnella
- propionibacterium
the longer the infectino exists within the RCS the more _____
oxygen is consumeed by bacterial activity and the more anaerobic becomes the RCS environment
chronic infections within the RCS tend to favor _______ bacterial flora
anaerobic
______ is responsible for an endo infection
NO one organism
all endo infections are _____
mixed or polymicrobial
what bacteria are endo infections
mostly facultative and obligate anaerobes
what environments can facultative anaerobes live in
aerobes which can survive in anaerobic environment
how can facultative anaerobes become more numerous and virulent
with addition of oxygen
would it benefit obligate anaerobes to add oxygen
no NaOCl liberates O2
when does biofilm become more varied, complex and difficult to control
when the tooth is further challenged by salivary contact or operative contamination
how do you avoid biofilm becoming more varied
- avoid leakage of rubber dam or temporary
- avoid iatrogenic contamination during treatment
how do we destroy bacteria
bleach or NaOCl or 8.3% sodium hypochlorite
what is necessary for bleach to act on bugs
- bugs must adhere to host surfaces
- obtain nutrients from the host
- multiply
- invade tissue
-overcome host defenses - induce tissue damage
what does bleach do
- disinfects over time
- dilutes and inactivates toxins
- dissolves substrate over time
- dissolves necrotic tissue over time
- flushes and floats out debris
- lubricates canal
what are diverse shapes resistant to
mechanical shaping: files never reach all spaces in the complex pulpal system
what amount of NaOCl is typically required
10-12 cc
how often must NaOCl be replenished and why
3-5 minutes because it degrades rapidly to NaCl in the canal
what is the 30/30 rule
NaOCl must be in contact with shaped canal a minimum of 30 minutes after canal enlarged to #30 or larger
what will happen to a canal smaller than #30
it will seldom ever allow any irrigant to reach the apical third of the canal
what do intracanal medications do
medications placed within the canal system between appointments
- intended to increase local anti microbial action and to further decrease the microbial challenge within the RC system - decreases amount of microbes
what intracanal medications are not acceptable
CMCP, Formocresol, cresatin, beachwood creosote
what is the intracanal medicatino of choice
CaOH
what is the pH of CaOH
between 11-12
what are the properties of CaOH
- discourages most microbial growth
- long lasting
- no reported allergies
- easy to apply to remove as a paste
what is the intracanal medication CaOH called in clinic
Ultracal
the use of antibiotics to relieve pain in endo is ______
useless
when are systemic antibiotics useful
only in acute P-R infections (swelling and fever) or for a patient who is immuno supressed
what symptoms do not require antibiotics
symptomatic pulpitis, symptomatic apical periodontitis, a draining sinus tract, or localized swelling
what temperature qualifies as a fever
100.3 F
drainage is accomplished by____
Incision and drainage
do you give antibiotics with incision and drainage
yes
use antibiotics in conjunction with definitive procedures to debride and drain where there is:
persistent or spreading infection
- systemic involvement with temperature over 100 deegrees
- medically compromised patient
- pre med when indicated
what happens if the bacteria from the infected pulp gainentry into the periradicular tissue and the immune system
acute periradicular abscess, cellulitis or both
- patient experiences swelling, fever, and mild to severe pain
depending on the relationship of the apices of the involves tooth to the muscular attachments, virulence factros and host resistance the swelling may be _______
localized to the vestibule or may extend into a fascial space (cellulitis)
what systemic manifestations with cellulitis patients have
fever chills and lymphadenopathy headache and nauses
what qualifies as a serious critical infection of the fascial plane
- the involved tooth may not show radiographic evidence of a widened PDL space, most cases the tooth elicits a positive response to percussion and the periradicular area is tender to palpation
is lesion exits coronal to muscle attachment it is generally on ______
attached gingiva or alveolar mucosa and we have a localized abscess
what are fascial spaces
potential anatomic areas that exist between the fascia and underlying organs and other tissues. during an infection these spaces are formed as a result of the spread of purulent exudate
what is the spread of infections of odontogenic origin into the fascial spaces of the head and neck determined by
the location of the root end of the involved tooth in relation to its overlying buccal or lingual cortical plate and the relationship of the eapex to the attachment of a muscle
critical infections have the potential to be ____ if not treated aggressively
lethal
why do we need to be cautious of 2nd and 3rd molar infections
they can cause cellulitis in the submandibular space and cause difficulty swallowing
- there is access from submandibular space to sublingual and submental
what is Ludwigs angina
3 spaces (submental, submandibular, and lsublingual) are infected and it can be life threatening
endodontic infections may be classified according to:
-location
-symptoms (acute or chronic)
- degree of virulence or organization (localized or diffuse spreading)
what are the locations of endodontic infections
- intraradicular
- extraradicular
what is intraradicular caused by
bugs colonizing within the RCS
what is extraradicular infection usually a sequel to
untreated intraradicular infection
what is extraradicular infection characterized by
microbial invasion of the periradicular tissues resulting in inflammation and infection. AAA or CAA
what are the 3 subclasses of intraradicualr infections
- primary infections
- secondary infections
- persistent infection
what is primary infection caused by
caused by bugs that initially invade and colonize necrotic pulp tissue within the RCS
what is secondary infection caused by
bugs not present in the primary infection but introduced into the RCS sometime following professional intervention (secondary to professional intervention; iatrogenic by definition)
what is persistent infectino caused by
bugs that were members of a primary or secondary infection and in some way resisted intracanal antimicrobial procedures and were able to endure periods of nutrient deprivation within the RCT - failure of RCT to heal
what is a virulence factor in RCS
the ability to form BIO
- neighboring cells of different species can produce enzymes such as B lactamase, catalase and proteinases that are retained in the biofilm matrix and can protect other bacteria against antibiotics and host defenses
gram negative anaerobes can cause direct tissue damage and osseous breakdown by releasing:
- enzymes: collagenase, chondroitinase, hyaluronidase
- endotozins: toxic substances associated with the oter cell walls that are released upon destruction of the cell walls and exotoxins
- LPS (in gram negative)
- peptides/amino acids
what is a virulent facultative anaerobe
staphylococcus aureus (aka) S. pyogenes (gram positive) can cause supprative infections
what does staphylococcus produce
penicillinase- a beta lactamse that has the potential to render penicillin ineffective
how do you treat staphylococcus aureus
Augmentin
what is augmentin made of
amoxicillin and clavulanic acid
what does clavulanic acid do
inhibits penicillinase
