MICROBIOLOGY & IMMUNOLOGY IN ENDODONTICS

DR.SADASIVAREADER

CHETTINAD HEALTH CITY

INTRODUCTION

• Most changes in pulp and periradicular tissues are of bacteriological and must be dealt with as infectious processes.

• Bacteria play a major role in pathogenesis of pulpo-periradicular lesion, a fundamental knowledge of endodontic microbiology needed to understand.

• 1. The role of bacteria in these diseases.• 2.Pathways of pulp and periradicular

tissues.• 3. Response of pulpal and periradicular

tissues to bacterial infection.• 4. Methods used to control and eradicate

root canal infection during root canal treatment.

• The intact hard tissues of the tooth normally protect the pulp by acting as physical barrier.

HISTORY

• 1890- Miller – demonstrated presence of bacteria in necrotic pulp tissue.

• Predominant species were streptococci, micrococci, and small% of anaerobic bacteria.

• Kakehashi etal – experiment with germ free rats – failed to create lesions.

• Poly microbial infections.

Flora of root canal and periradicular lesions• Most of them – multi bacterial.• Predominance of facultative

organisms• Obligate anaerobic species • Gram negative cocci• Lactobacilli• spirochetes• Bacteroides- black pigmented

species

MICROBIAL VIRULENCE&PATHOGENICITY• In 1965, Hobson gave an equation

showing the relation of number of microorganisms , their virulence, resistance of host and severity of the disease.

• Number of microorganisms x Virulence of microorganisms = severity of the disease

--------------------------------------------------- resistance of host

VARIOUS VIRULENT FACTORS• 1. Lipopolysaccharides(lps)• 2. Extra cellular vesicles• 3. Enzymes• 4.Fatty acids• 5. Polyamines• 6. Capsule• 7.Pilli

Lipopolysaccharides(LPS)

Present on the surface of gram negative bacteria.

LPS HAVE NON SPECIFIC antigens which are not neutralized by antibodies.

ENDOTOXINSDiffuse in to dentin .Studies have shown the

relationship between endotoxins and the periradicular inflammation.

EXTRACELLULAR CELLULAR VESICLES• Produced by gram-ve bacteria in

the form of endotoxins.• Vesicles contain various

enzymes and toxic products- responsible for haemaggulutination, hemolysis and bacterial adhesion

ENZYMES

• Helps in spread of infection• Neutralization of the immunoglobulin

and complement components• PMN leucocytes release hydrolytic

enzymes which degenerate and lyse to form purulent exudates and have adverse effects on the surrounding tissues.

FATTY ACIDS&POLYAMINES• ANAEROBIC BACTERIA –produces

propionic acid, butryicacid.• They cause neutrophil chemotaxis,

degranulation,and stimulate interleukin -1 production which causes bone resorptionand periradicular diseases.

• Polyamines are active chemicals found in infected canals. Cadaverine, putrescine, spermidine are polyamines.

Factors influencing the growth and colonization of microorganisms• Influence of oxygen• Nutritional factors• Bacteriocins• Coaggregation• Bacterial relationships

Microbial ecosystem of the root canal system• NAIDORF summarized the few

generalization in relation to organisms isolated freom the root canals.

• 1. Mixed infections are more common than single organisms.

• 2.Pulp contains flora almost similar to that of oral cavity.

• 3. Approximately 25 % of isolated organisms are anaerobic.

• 4. organisms isolated from flare-up as well as asymptomatic cases are almost similar.

Microbiology of infected root canal

BIOFILM

• Biofilm is defined as community of microcolonies of microorganisms in an aqueous solution that is surrounded by a matrix made of glycocalyx, which attaches the bacterial cells to a solid substratum.

• One of basic survival methods- in times of starvation.

• A BIOFILM has the following attributes:• Autopoiesis• Homeostasis• Synergy• Communality

Classification of biofilms

• Intracanal microbial biofilms• Extraradicular microbial biofilms-

Enterococcus faecalis responsible for therapy resistant .

• Periapical microbial biofilms- Actinomyces and P. propionicum have been shown to form periapical lesions resistant to endodontic therapy.

PATHOGENICITYOF BACTEROIDES• Related to the presence of LPS and Peptidoglycans• 1. induce hormones like cytokinins which play

important role in inflammation.• Stimulate B-lymphocytes• Activate complement cascade• Release various enzymes like collgenase• Enhance production of various pain mediators like

bradykinin,histamine and prostaglandins• LPS once released as ENDOTOXIN causes

biological effects including inflammationand bone resorption.

Fungi& viruses

• Using PCR, Candida albicans was detected in 21 % of infected root canals.

• Bacteriocins are viruses that infect bacteria and carry DNA in to the genome of the bacteria. HIV , CYTOMEGALO VIRUS, and EPSTEIN BARR virus – associated with periapical disease.

Microbiology of periradicular endodontic infections• Biofilms are formed in the periapical region• Periapical lesions contains macrophages,

lymphocytes(T- cells and B-cells), plasma cells, and neutrophils.

• Their function is to prevent microorganisms from invading periradicular tissues.

• The mosty common cause of persistent periradicular infections is incomplete debridement of the root canal system. Therefore three dimensional sealing of the rootcanal system is necessary for resolution of periapical pathologies

Microbiology of root canal failures• More facultative bacteria rather than

strict anaerobes• Enterococcus fecalis.

Propionbacterium alactolyticus, P.propionicum in filled root canal failure cases.

• Vast majority of endodontic treatment failures are caused by intraradicular infections.

IDENTIFICATION OF THE BACTERIA• GRAMS STAIN- helps in

differentiating Gram positive and Gram negative organisms.

• CULTURE: • Molecular diagnostic methods• DNA- DNA hybridization method• Polymerase chain reaction

How to combat microbes in the endodontic therapy• Thorough cleaning & shaping of the root canal system-

irrigants like NAOCL, H2O2, EDTA - excellent tissue dissolving and microbial agents.

• Oxygenating a canal simply by opening is detrimental to anaerobes.

• Drainage by canal or by soft tissues decrease discomfort caused by inflammatory mediators.

• ANTIBIOITICS :Drug of choice is Penicillin vk bcos of its spectrum of microbial activity against most of the bacteria associated with endodontic infections and also of its low toxicity.

• INTRACANAL MEDICAMENTS• Use of CAOH2, CHX2% TRIPLE ANTIBIOTIC PASTE - is

beneficial in necrotic pulps

THANK U