2017/2018- Essay 2

Question 1

Title

Answer 1

Dental Plaque Formation and Species Succession: Transition from a Healthy to a Pathogenic State

Question 2

What is dental plaque?

Introduction

Describe the species succession during dental plaque formation and the ensuing changes in the microbial community with progrssion from a healthy to a pathogenic state.

Answer 2

What is dental plaque?
- complex and dynamic biofilm
- surface of teeth
- in oral cavity
- complex of microbial community embedded in a matrix of extracellular polymeric substances (EPS)
- >derived saliva and bacterial products

Dental plaque formation and species succesion
* >influenced: evironmental and host factors
* * Poor oral hygeine
* High sugar diet
* Reduced saliva flow-> acidic environment
* Smoking, stress, medical conditions
* >favoring proliferation of pathogenic species
* Leadinf Shift in microbial community compostion from healthy ->pathogenic

Infection
-dental caries
-periodontal disease

• This essay will explore hoq these changes come about within the microbial community during dental plaque formation

Question 3

Paragraph 1

Describe the species succession during dental plaque formation and the ensuing changes in the microbial community with progrssion from a healthy to a pathogenic state.

Answer 3

Initial attachment- Pellicle Formation
- attachment
- facilitated by salivary proteins and lipids (receptors for adhesion) to tooth surface
- forms thin, acellular layer= pellicle

Early colonizers
- attachment of pioneer species
- Streptococcus species
- Actinomyces species
- adhere to pellicle via adhesins
- establish microbial community

At this stage
* Initial bacterial colonisers multiply
* secrete EPS
* Forming microcolonies
* -Biofilm - harmless
-Bacterial community dominated by commensal species

Question 4

Refer to species succession

Paragraph 2

Describe the species succession during dental plaque formation and the ensuing changes in the microbial community with progrssion from a healthy to a pathogenic state.

Answer 4

Shift from healthy to pathogenic- Biofilm maturation and diversity
- Biofilm matures , diversity increases
- Actinomyces/gram postive bactera colonize upper layers of the biofilm
- microbial community more complex and pathogenic
- availability of oxygen and nutrient decrease
- anaerobic niches
- favor growth of pathogenic bacteria
- - > dominance of certain species over others
- Recruitment of Anaerobic bacteria
- Porphyromonas gingivalis
- Prevotella intermedia
- colonize the deeperlayers of the bioflm
- produce enzymes that degrade extracellilar matrix
- promote invasion of host tissues
- Produce virulence factors

Virulence factors
- lipopolysaccharides
- proteases

Disease development
- gingivalis
- periodontitis

Question 5

Conclusion

Describe the species succession during dental plaque formation and the ensuing changes in the microbial community with progrssion from a healthy to a pathogenic state.

Answer 5

• Dental plaque formation involves species succession and dyamic interaction - oral microorganisms
• Driven by environment and host factors

Importance
* Understanding mechanisms this transtion in dental plaque essential
* >maintain oral health prevent oral diseases such as gingivalis and periodontitis
* Therefore, goof oral health practices, dental check ups, balanced diet
* to promote healthy oral community qne preventing developemt of pathogenic dental plaques