Endodontics
Course Review
Enoch Ng, DDS 2014
Microbiology and Infection
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Why – pulpal and apical disease
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How – access, cleaning/shaping, canal disinfection, obturation, final restoration
Inflammation and Infection
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Inflammation – SHaRP, loss of function – protective attempt by organism to remove injurious stimuli and initiate
healing process
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Infection – pathologic condition where host is detrimentally colonized by non-host species, competition
between host and microorganisms
o
Primary pathology – bacteria
Other pathogens – viral, fungal
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Microorganisms are the cause for pulpal and apical pathology
o
Germ free rats with pulpal exposure – no necrosis or infection
o
Normal rats with pulpal exposure – all pulp tissue necrotic with extensive bacterial spread
Bacteria must get into pulp to induce apical inflammation
Contamination via oral saliva
Necrotic tissue alone does NOT cause inflammation
Routes of infection
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Pulpaldentin complex protected by dentin
o
Compromised by caries, cracks and fractures, restorative procedures, attrition/abrasion, enamel defects
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Dentin tubules
Bacterial Diameter = 0.4-0.7um
DEJ
Near Pulp
Diameter
0.8um
2.5um
Number
15-20K
45-60K
o
May travel up to 400um into dentin in 3 weeks
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Vital pulp – helps prevents infection
o
Outward dentinal fluid movement
o
Tubular contents – odontoblastic processes, collagen fibrils)
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These factors not present in necrotic pulp – easier for bacterial invasion
o
During/after treatment
Bacterial/calculus/biofilm remnants
Leaking rubber dam, leakage/breakdown of temporary, delay in permanent restoration
Contaminated instruments, root canal filling material exposure
Bacterial Morphology
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Gram +
ve
– thick cell wall peptidoglycan, teichoic and lipoteichoic acid
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Gram –
ve
– LPS, thin peptidoglycan cell wall
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Major endodontic pathogens are obligate anaerobes
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Pathogenicity – ability of microorganism to CAUSE disease
o
Biofilm formation
– resists phagocytosis and antimicrobials
Cells firmly attached to a surface, enmeshed in a self-produced matrix of polysaccharides
Broader habitat range of growth, increased metabolic diversity and efficiency, protection, and
genetic exchange for antibiotic resistance
Neutralizing enzymes in biofilm, surface bacteria absorbing antibiotic
Bacteria in altered growth/stationary phases