Endodontics
Course Review
Enoch Ng, DDS 2014
Infection
-
Intrarradicular infections – inside root canal system
o
Primary – initial invasion into root canal system
Polymicrobial – gram +
ve
and –
ve
, >3 specimens
Once microbes invade necrotic pulp, multiply and infect root canal system and dentinal tubules
Coronal region – rapidly growing facultative anaerobes
Apical region – obligate anaerobes
Bacteroides and gram +
ve
anaerobic rods in apical region
o
Secondary – invasion during course of treatment/intervention
o
Persistent – organism survives treatment (clinically indistinguishable from secondary)
1-2 bacterial species, mostly gram +
ve
facultative anaerobes
Primary cause of non-healing endo lesion (inaccessible to debridement, resistant to irrigant)
Both dentin layer bordering pulp (81%) and cementum (62%)
Intracanal bacteria/biofilms primary cause of persistent endo infections
E. faecalis isolated in 38% of endo treated teeth – binds to human collagen and invades
dentinal tubules via ACE binding protein
-
Extrarradicular infections – invasion into apical tissues beyond root canal system
o
Can result from
Extension of intrarradicular infection
Persistence of bacteria in apical periodontitis lesion
Apical extrusion of bacterial infected debris during instrumentation
Independently from intrarradicular infection (Actinomyces)
o
Obligate anaerobes have also been isolated from apical cementum
Biofilms implicated in some instances
o
May lead to formation of apical abscess – accumulation of dead neutrophils, bacterial byproducts,
bacteria, proteins, fluids
Drainage may form a sinus tract
Symptoms
-
Prevotella – pain, sinus tract formation, foul odor
-
Prevotella, peptostrep, eubacterium – pain, swelling, wet canals (hemmorhagic/purulent exudates)
-
Peptococcus, peptostrep, eubacterium, porphyromonas – percussion pain
Irrigants and Medicants
-
NaOCl – hypochlorous acid when contacting organic debris
o
Oxidizes sulfhydryl groups of bacterial enzymes – disrupts metabolism
15min to remove bacteria and biofilms
o
Inhibits DNA replication, disrupts structural proteins
o
Alkaline pH
-
CaOH – creates hydroxyl ions/free radicals = diffuse through dentinal tubules and destroy bacterial membrane
o
Physical barrier – limit proliferation of residual bacteria, prevent reinfection
o
Alkaline pH
o
Breaks down LPS, reacts with bacterial DNA and disrupts replication and metabolism via mutations
-
An infected canal must have the infected dentin removed (cleaning the dentin walls) via instrumentation
