📌 MICROORGANISMS ASSOCIATED
📣 Periodontal Health
🔹Beneficial species of the host affect the disease progression by preventing the colonization/proliferation of pathogenic microorganisms, e.g. hydrogen peroxide produced by S.sanguinis is lethal to A. actinomycetemcomitans.
🔹Sometimes, these species also degrade the virulence factors produced by the pathogens.
⭐ Following are the beneficial microorganisms:
🔺 S. sanguinis
🔺 S. mitis
🔺 Capnocytophaga spp.
🔺 Veillonella
🔺 Atopobium sp.
🔺 Gemella sp.
📣 Chronic Gingivitis/Dental Plaque-induced Gingivitis
🔺 Gram-positive organisms:
▪️ S. sanguinis
▪️ S. oralis
▪️ S. mitis
▪️ S. intermedius
▪️ A. viscosus
▪️ A. naeslundii
▪️ Peptostreptococcus micros
🔺 Gram-negative organisms:
▪️ P. intermedia
▪️ Veillonella parvula
▪️ F. nucleatum
▪️ Hemophilus
▪️ Campylobacter spp.
▪️ Capnocytophaga.
📣 Chronic Periodontitis
▪️ P. gingivalis
▪️ P. intermedia
▪️ T. forsythia
▪️ F. nucleatum
▪️ Eikenella corrodens
▪️ C. rectus
▪️ A. actinomycetemcomitans
▪️ Treponema
▪️ P. micros
▪️ Eubacterium spp.
▪️ Herpes virus group: EBV-1, HCMV
📣 Localized Aggressive Periodontitis
▪️ A. actinomycetemcomitans
▪️ P. gingivalis
▪️ C. rectus
▪️ F. nucleatum
▪️ E. corrodens
▪️ Capnocytophaga spp.
▪️ Eubacterium brachy
▪️ B. capillus
▪️ Spirochetes
▪️ Herpes viruses including EBV-1, HCMV.
📣 Necrotizing Periodontal Disease
▪️ Spirochetes
▪️ P. intermedia
📣 Abscesses of Periodontium
▪️ P. intermedia
▪️ P. gingivalis
▪️ F. nucleatum
▪️ T. forsythia
▪️ P. micros.
📌 POINTS TO PONDER
🔹 Ecosystems/niches present in the oral cavity are:
✴️Supragingival hard surfaces: (teeth, implants, restoration and prostheses), periodontal/peri-implant pocket, buccal epithelium, palatal epithelium, epithelium of the floor of the mouth and dorsum of the tongue.
✴️Subgingival ecologic niches present in the oral cavity are: Tooth/implant surface, gingival exudate fluid medium, surface of epithelial cells and superficial portion of the pocket epithelium.
🔹New names of various periodontal bacteria
Previous Name Current Name
- Bacteroides gingivalis Porphyromonas gingivalis
- Bacteroides intermedius Prevotella intermedia
- Bacteroides melaninogenicus Prevotella melaninogenica
- Bacteroides forsythus Tannerella forsythia
- Wolinella recta Campylobacter rectus
- Actinobacillus actinomycetemcomitans Aggregatibacter actinomycetemcomitans
📌 VIVA VOCE
Q1. Who discovered Tannerella forsythia?
Ans. Tannerella forsythia was first isolated at the Forsyth Institute from subjects with progressing advanced periodontitis in the mid 1970s and was described as Fusiform Bacteroides by Tanner et al.
Q2. Who discovered Actinobacillus actinomycetemcomitans?
Ans. Actinobacillus actinomycetemcomitans was first isolated by German microbiologist Klinger, in 1912 from lesion of cervicofacial actinomycosis. The microorganism was isolated together with A. israelli. Hence, the species name actinomycetemcomitans means together with Actinomyces. Genus name Actinobacillus, “actino” referring to star-shaped internal morphology of the colonies and bacillus referring to cell shape (rod-shaped).
Q3. What are the various species of Bacteroides?
Ans. The various species of Bacteroides are as follows:
- Asaccharolytics: P. gingivalis
- Intermediate level of carbohydrate fermenter: P. intermedia
- Highly saccharolytic: P. melaninogenica.
Q4. Name the bacteria which invade epithelial cells.
Ans. Bacteria invading epithelial cells are as follows:
- P. gingivalis
- A. actinomycetemcomitans
- Spirochetes (T. pallidum)
- F. nucleatum.
Q5. Name the motile bacteria.
Ans. Motile bacteria are:
- Spirochetes
- C. rectus
- Selenomonas.
Q6. Name the bacteria which produce leukotoxin (Ltx).
Ans. Bacteria producing leukotoxin are:
- A. actinomycetemcomitans
- C. rectus.
Q 7. Name various gingipains produced by P. gingivalis.
Ans. Arginine-specific proteinase, i.e. RgpA and RgpB and lysine-specific proteinase, i.e. Kgp.
Q 8. Name various virulence factors produced by P. gingivalis.
Ans. Collagenase, endotoxin, fatty acids, ammonia, hydrogen sulfide, indole, hemolysin, fibrinolysin, phospholipase A and bone resorption inducing factor.
Q 9. Name various virulence factors produced by A.actinomycetemcomitans.
Ans. Leukotoxin, chemotaxis inhibitor, Fc binding protein and immunosuppressive factors.
Q10. What are the differences between transmission, contagious and translocation?
Ans. Following are the differences between:
🔺TRANSMISSION:
- Passing of microorganism directly from one person to another.
- Periopathogens are transmissible within the members of family.
- Transmission of cariogenic species from mother to child.
🔺CONTAGIOUS:
- Refers to likelihood of a microorganism causing disease after being transmitted from an infected to an uninfected host.
🔺TRANSLOCATION:
- Intraoral transmission of bacteria from one niche to another. Also called as cross-infection.
📌 MULTIPLE CHOICE QUESTIONS (MCQs)
💡 Leukotoxins are produced by which of the following periopathogens:
- P.gingivalis
- P. intermedia
- A.actinomycetemcomitans
- F.nucleatum
Answer : 3
💡 Which microorganism is increased in pregnancy:
- Prevotella intermedius
- Porphyromonas gingivalis
- Porphyromonas melaninogenicus
- Eikenella corrodens
Answer : 1
💡Which of the following bacteria have the capacity to invade host tissue cells directly?
- P. gingivalis
- A. actinomycetemcomitans
- T. denticola
- All of the above
Answer : 4
💡 Which of the following is not included in the Green complex?
- Aggregatibacter actinomycetemcomitans serotype a
- P. gingivalis
- Eikenella corrodens
- Capnocytophaga spp.
Answer : 2
💡 Which of the following complex is most closely attached to destructive periodontal diseases:
- Red complex
- Green complex
- Orange complex
- Purple complex
Answer : 1
💡Which of the following bacteria is associated with periodontal health?
- S. sanguis
- S. mitis
- Capnocytophaga spp.
- Veillonella
- All of the above
Answer : 1