33 - Oral ecology + Factors or oral bacterial homeostasis

Question 1

Definitions

Answer 1

Oral ecology ⇢ organisms that live in the mouth

Oral eubiosis ⇢ microbial balance within the oral cavity

Oral microflora ⇢ acquired from birth + can be resident/transient

• Acquired from saliva, food. H2O
• For 1st period of life ⇢ S.Salivarus is dominant

Question 2

Oral microorganisms

Answer 2

Colonise areas called niches

This includes supragingival + subgingival plaque + tongue coating

On mucosa surfaces

• S.Oralis, S.sanguis, Neisseria, Haemophilus + Veillonella

On tongue

• S.salivarius, Veilonella, Pepto streptococcus, G⁺/G^-ve rods

Question 3

Diseases of oral floras

Answer 3

Abscesses

Dental caries

Gingivitis

Periodontal diseases

Question 4

Important oral bacteria

Answer 4

Streptococci

• Facultative anaerobic cocci
• Produce lactic acid
• Some are implicated in caries

Actinomyces ⇢ Facultative anaerobes

Lactobacillus

• Facultative anaerobes
• Produce lactic acid
• Causes caries in dentin

Question 5

Gram⁺ oral cocci

Answer 5

Cocci/Rods/Irregular shape

O2 tolerance varies from anaerobes to strict anaerobes

Most are fermentative

Streptococci of resident flora

• S.mutans ⇢ caries + bacterial endocarditis
• S.salivarius ⇢ colonies mucosal surface
• S.angiosus ⇢ isolated detnal plaque
• S.mitis ⇢ opportunistic pathogen that causes endocarditis

Question 6

Gram^-ve

Answer 6

Aerobes

• Neisseria . muscosa/sicca/subflava

Anaerobes

• Veilonella . atypica/dispar/parvula

Porphyromonas gingivalis ⇢ periodontal pathogen

Prevotella intermedia ⇢ periodontal pathogen

Fusobacterium nucleatum

Actinomyces ⇢ associated w/root caries

Question 7

Factors affecting growth of MOs in oral cavity

Temperature

Answer 7

± 34-36°C

Variable in teeth + mucosa

MOs do not cause metabolic disorders ⇢ due to exposition to extreme temperatures during eating

Question 8

pH

Answer 8

[H⁺] = ± 6.7 - 7.3

Maintained by salivary flow + buffering systems

Lactobacillus + S.mutans develop in this acid medium niche

Gingival sulcus ⇢ pH is alkaline 7.5-8.5

Question 9

Redox potential

Answer 9

Negative redox potential ⇢ anaerobes develop

• This includes ⇢ approximal surfaces, fissures, gingival sulcus

Positive redox potential

• Buccal + palatal mucosae, back part of tongue

Question 10

Nutrients

Answer 10

Includes:

• Desquamated epithelilal cells
• Gingival fluid
• Saliva components
• Residues of host’s food