Download Lecture for 3rd yr students- 22/2/2015

22/2/2015
Assalam Alekkum
Dr Gaurav Garg, Lecturer
College of Dentistry, Al Zulfi, MU.
Learning Objectives
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At the end of lecture students should know:
Role of bacteria in Pulp & Periradicular diseases
Pathways of Pulpal & Periradicular infection
Flora of the Root canal & Periradicular lesion
Response of Pulp & Periradicular tissue to bacterial
infection
Methods of control & eradication of root canal infection
Role of bacteria
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The intact hard tissues of the tooth normally
protect the pulp by acting as physical barriers to
noxious irritants.
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Causes of pulp/ periradicular disease can be
physical, chemical and bacterial.
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Bacteria cause predominately all pathoses of the
pulp and the periradicular tissues.
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To effectively treat endodontic infections,
clinicians must recognize the cause and effect of
microbial invasion of the dental pulp space and
the surrounding periradicular tissues.
Pathways of Pulpal &
Periradicular infection
ROUTES OF
MICROORGANISM INGRESS
1. Through the
open cavity
4 Through extension
of a periapical
infection
from adjacent
infected
teeth
2. Through the
dentinal tubules
5. Through the
blood stream
(Anachoresis)
3. Through
the gingival
sulcus & periodontal
Ligament
(through lateral canal)
Flora of the root canal &
periradicular lesion
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Root canal infection is a mixed infection
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85% to 98% of the bacteria are anaerobic.
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The most frequently found anaerobic species are
Bacteroides (Porphyromonas & Prevotella) and
gram-positive anaerobic rods.
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Acute symptoms are usually related to the
presence of specific anaerobes, such as
Porphyromonas gingivalis, Porphyromonas
endodontalis, and Prevotella buccae.
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A small percentage of facultative anaerobic
bacteria are also present
Bacteria prevalent in endodontic
infections
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1. Anaerobic gram negative
 Porphyromonas, Fusobacterium,
Prevotella
2. Facultative gram negative
 Neisseria, Capnocytophaga
3. Aerobic gram positive
 Proprionibacterium, Peptostreptococcus
4. Facultative gram positive
 Actinomyces, Streptococcus,
Lactobacillus
Response of Pulp & Periradicular
tissue to bacterial infection
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Dental pulp and periradicular tissues react to bacterial
infections as do other connective tissues elsewhere in
the body.
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The extent of damage as a result of bacterial penetration
into these tissues depends on the virulence factors of
participating bacteria and the resistance factor/ Immunity
of the host tissues.
Infection rate
virulence factor
Immunity
No Disease
Disease
Response of Pulp & Periradicular
tissue to bacterial infection
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The degree of pulpal and periradicular response to
bacterial irritants varies from slight tissue inflammation to
complete pulpal necrosis or acute periradicular
osteomyelitis with systemic signs and symptoms of
severe infection.
Response of Pulp & Periradicular
tissue to bacterial infection
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Direct exposure of pulpal tissue to microorganisms is not a
prerequisite for pulpal response and inflammation.
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As a result of the presence of microorganisms in the dentin, a
variety of immunocompetent cells can be recruited to the dental
pulp.
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It is initially infiltrated by chronic inflammatory cells, such as
macrophages, lymphocytes, and plasma cells.
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The concentration of these cells increases as the decay progresses
toward the pulp.
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Polymorphonuclear leukocytes are the predominant cells at the site
of pulp exposure.
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Mild infections - do not result in significant changes in the pulp.
Moderate-to-severe infections
Release of inflammatory mediators (neuropeptides, vasoactive amines, kinins,
complement components, arachidonic acid metabolites, and cytokines )
increased vascular permeability, vascular stasis, and migration of leukocytes.
lysosomal enzymes released from disintegrated leukocytes, can cause small
abscesses and necrotic foci in the pulp.
Uncontrolled pulpal infection can result in total pulp necrosis and colonization of
bacteria in the root canal system.
Egress of these organisms or their by-products from the root canal system into
the periradicular tissues causes development of apical lesions.
Periapical inflammatory reactions are
apparent in advance of total pulpal
necrosis, when vital pulp is still present.
Periapical responses
to pulpal infection
Bacterial products
PMNs
IL-1, IL-6
TNFα
PGE
MF
L
IL-1
+
Ag
B
IL-2
Methods of control & eradication
of root canal infection
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The steps involved in the disinfection of root canals are:
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isolation of the involved teeth
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Sanitation of the field of operation and use of sterile instruments
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Removal of bacteria, their by-products, and debris
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Prevent recontamination of the cleaned root canal
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Obturation of the root canal in three dimensions
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Placement of leak-resistant permanent restorations.
SYSTEMIC USE OF MEDICATIONS DURING
ROOT CANAL THERAPY
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Analgesics ( NSAIDS) and antibiotics are the major classes of medications
used during the course of root canal treatment.
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Antibiotics are indicated only if there is diffuse, rapidly spreading infection
(cellulitis), fever & lymphadenopathy.
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Because of the nature of root canal flora, however, no single antibiotic is
always effective against all root canal infections.
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Penicillin remains the antibiotic of choice because it is effective against
most bacteria found in infected root canals.
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In case of allergy, erythromycin is the drug of second choice.
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Cleomycin produces a high concentration of this substance in the bone and
is effective against anaerobic bacteria, it could be used as an alternative.
References
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Principal & Practice of Endodontics; Torabinezad
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Textbook of Endodontics; Franklin S. Weine
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Endodontics; Ingle & Bakland
Thank you!