9. Oral biofilms and calculus

Question 1

Stages in the formation of dental plaque

Answer 1

1. Acquired pellicle
2. Initial collonisation
3. Secondary colonisation
4. Maturation and biofilm growth
5. Plaque mineralisation and calcification

Question 2

Acquired pellicle

Answer 2

• Formed instantly after brushing
• Salivary and glycoproteins
• Thin film that is attachment site for bacteria

Question 3

Intial colonisation

Answer 3

• Within a few hours
• S. Sanguis, S. Oralis

Question 4

Secondary colonisation

Answer 4

• 24-72 hours
• More diverse microorganisms including actinomyces, preveotella and fusobacterium
• Adhere to initial colonisers

Question 5

Maturation and biofilm growth

Answer 5

• After a few days
• Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola
• Gram negative and positive bacteria

Question 6

Plaque Mineralization and Calcification

Answer 6

• Over longer period
• Biofilm hardens due to salivary minerals

Question 7

Types of plaque

Answer 7

• Supragingival
• Subgingival

Question 8

Calculus composition

Answer 8

• Inorganic(mineral) components
• Organic(cellular and extracellular matrix) components

Question 9

Inorganic component of calculus(mineral)

Answer 9

• 40-60% depending on location
• Calcium phosphate crystals organised into four mineral phases-Octacalcium phosphate, hydroxyapatite, whitlockite and brushite

Question 10

Organic component of calculus

Answer 10

• 85% cellular and 15% extracellular matrix
• Cellular density within calculus very high
• Extracellular matrix mostly proteins and lipids

200,000,000 cells per milligram
-Cells primarily bacterial, some fungal-candida and species of archaea

Question 11

Common sites for calculus formation

Answer 11

• Buccal surfaces on maxillary molars
• Lingual surfaces of mandibular incisors

-Due to proximity to parotid and sublingual salivary glands

Question 12

Bacteria in present in fissures

Answer 12

• Gram positive bacteria
• Facultative anaerobes
• Streptococcus
• Actinomyces

Question 13

Bacteria present in proximal plaque

Answer 13

• Gram positive and negatve
• Facultative and obligate anaerobic bacteria
• Streptococcus
• Actinomyces
• Neisseria
• Veillonella
• Prevotella

Question 14

Bacteria present in gingival crevice

Answer 14

• Gram positive and negative
• Obligate anaerobes
• Streptococcus
• Actinomyces
• Eubacterium
• Fusobacterium
• Treponema

Question 15

Bacterial complexes

Answer 15

• Green
• Orange associated
• A-a
• Orange
• Red

Question 16

Bacteria in green complex

Answer 16

• E.corrodens
• Capnocytophagia species
  -C.gingivalis
  -C.Ochracea
  -C.Spitigena

E= Eikenella

Question 17

Bacteria in orange associated complex

Answer 17

• C.rectus(Cr)
• E.nodatum(En)

C=Campylobacter
E=Eubacterium

Question 18

Bacteria in A-a complex

Answer 18

A.Actinomycetemcomitans(Aa)

Question 19

Bacteria in orange complex

Answer 19

• P.Intermedia(Pi)
• P.micra(Pm)
• F. nucleatum(Fn)

Pi=Prevotella
Pm- Parvimonas
Fn=Fusobacterium

Question 20

Red complex bacteria

Answer 20

• P.gingivalis(Pg)
• T.forysthia(Tf)
• T.denticola

Pg=Porphyromonas
Tf=Tannerella
Td-Treponema