Aetiology of perio diseases part 1

Question 1

What is dental biofilm?

Answer 1

A complex microbial community (predominantly bacteria) found on tooth and oral surfaces in a matrix of bacterial and salivary origin, firmly adherent to the tooth surface.

Question 2

How does dental biofilm contribute to periodontal disease?

Answer 2

Biofilm allows pathogenic bacteria to interact within a matrix-enclosed environment, leading to inflammationof gingival and periodontal tissues.

Question 3

What are the two types of periodontal disease?

Answer 3

Gingivitis (inflammation of the gingiva) and periodontitis (inflammation of supporting tissues leading to bone and ligament loss).

Question 4

What is the role of saliva in dental plaque?

Answer 4

Saliva contains proteins and peptides with antimicrobial activity and forms a pellicle that influences bacterial attachment.

Question 5

What are the two main types of dental plaque?

Answer 5

Supragingival and subgingival plaque.

Question 6

What is the composition of dental plaque?

Answer 6

Cells (bacteria, epithelial cells, leukocytes), extracellular matrix (proteins, polysaccharides, lipids), and inorganic components (calcium, phosphorus).

Question 7

How does calculus form?

Answer 7

By mineralization of dental plaque, primarily with calcium and phosphorus from saliva.

Question 8

What is the acquired pellicle?

Answer 8

A conditioning film formed from salivary proteins and glycoproteins on the tooth surface, which aids bacterial attachment.

Question 9

Which bacteria are primary colonizers of dental plaque?

Answer 9

Gram-positive bacteria such as Streptococcus sanguis and Actinomyces viscosus.

Question 10

What is co-aggregation in biofilm formation?

Answer 10

The process by which genetically identical bacteria adhere to one another, promoting further bacterial attachment.

Question 11

What is the function of the intermicrobial matrix in plaque?

Answer 11

It retains bacterial products for interactions and provides an environment for nutrient exchange and waste removal.

Question 12

What role does dextran play in dental plaque?

Answer 12

Dextran, a polysaccharide, acts as a sticky adhesive material aiding bacterial colonization.

Question 13

What is the significance of F. nucleatum in biofilm?

Answer 13

It is an important bridging microorganism that connects primary and secondary colonizers in the biofilm.

Question 14

How do secondary colonizers attach in plaque?

Answer 14

They adhere to primary colonizers or the extracellular matrix of the biofilm, enhancing its pathogenicity.

Question 15

Why is subgingival plaque more resistant to removal?

Answer 15

It resides in a protected location, not subjected to intraoral abrasion or salivary defense components.

Question 16

What bacterial species dominate supragingival plaque?

Answer 16

Gram-positive cocci (e.g., Streptococcus) and rods (e.g., Actinomyces species).

Question 17

What are the main bacteria in tissue-associated subgingival plaque?

Answer 17

Porphyromonas gingivalis, Prevotella intermedia, Aggregatibacter actinomycetemcomitans.

Question 18

What are the key inorganic components of dental plaque?

Answer 18

Calcium and phosphorus, primarily from saliva.

Question 19

What is the significance of dental plaque in periodontal disease?

Answer 19

Plaque biofilm’s structure protects bacteria from host defenses and antimicrobial agents, allowing long-term survival and disease progression.

Question 20

How does bacterial colonization change plaque over time?

Answer 20

Plaque matures from primarily aerobic to anaerobic, with secondary and tertiary colonizers increasing its pathogenicity.

Question 21

How do early colonizers affect the biofilm environment?

Answer 21

Early colonizers like streptococci utilize oxygen, creating a low-oxygen environment that favors anaerobic bacterial growth.

Question 22

What is the role of lactate and formate in bacterial interactions?

Answer 22

These byproducts from streptococci and actinomyces are used by other bacteria like Veillonella for metabolism.

Question 23

How does Porphyromonas gingivalis benefit from other bacteria?

Answer 23

It uses metabolic products like succinate, produced by organisms like Capnocytophaga, to enhance its growth.

Question 24

What is the specific plaque hypothesis?

Answer 24

It suggests that periodontal disease results from the presence or increase of specific pathogenic microorganisms in dental plaque.

Question 25

What is the nonspecific plaque hypothesis?

Answer 25

It proposes that periodontal disease results from the accumulation of plaque and the collective effect of its microbial products.

Question 26

What are the main antimicrobial agents in saliva?

Answer 26

IgA, lactoferrin, lysozyme, and peroxidases.

Question 27

What is a biofilm?

Answer 27

A structured community of microorganisms enclosed in a self-produced matrix that adheres to surfaces.

Question 28

How does smoking affect plaque formation?

Answer 28

Smoking promotes plaque accumulation by reducing salivary flow and impairing immune response.

Question 29

What is the role of mechanical cleaning in plaque control?

Answer 29

It disrupts the biofilm structure, reducing bacterial colonization and preventing plaque maturation.

Question 30

What happens during plaque maturation?

Answer 30

Bacteria multiply, forming a thick biofilm with reduced oxygen levels, favoring the growth of anaerobic pathogens.

Question 31

What is the ecological plaque hypothesis?

Answer 31

It suggests that periodontal disease results from shifts in the balance of microbial species in the biofilm, influenced by environmental changes.

Question 32

How does the acquired pellicle protect the tooth surface?

Answer 32

It forms a barrier that influences bacterial attachment and can reduce enamel colonization by exogenous microorganisms.

Question 33

What is the significance of Campylobacter rectus in plaque biofilm?

Answer 33

It is a secondary colonizer that contributes to the pathogenicity of plaque and periodontal disease.

Question 34

How does plaque biofilm resist antibacterial agents?

Answer 34

The biofilm structure retains bacterial products and shields bacteria from external agents.

Question 35

What factors influence plaque formation?

Answer 35

Mechanical cleaning, smoking, diet, physical space, and the host’s innate defense system.