27 - oral ecology. Oral microflora. Types of microorganims. Microbial interactions. oral econiches. Characteristics of oral microflora according to age

what is oral microflora?

• community of microorganisms coexisting in the oral cavity as its primary habitat.

• Oral microflora is acquired after birth as new-born babies have no bacteria in their mouths, over time the oral cavity becomes colonised by strains of bacteria that eventually form the resident microflora and over time stability is reached

Types of microorganisms

• bacteria

• fungi

• protozoae

• virus

bacteria

• most abundant in oral cavity

• e.g streptococcus mutans, actinomyces

fungi

• found in smaller numbers but can overgrow in certain conditions

• e.g candida albicans

Protozoa

• less common but present in some individuals

• e.g entamoeba gingivalis

virus

• temporary and persistant pathogens

• e.g temporary - influenza

• e.g permanent - herpes simplex virus

types of microbial interactions

• Neutral - two organisms living together without affecting each other

• Synergy - two organisms living together, both are mutually favoured leading to enhancment of their effects

• Antagonism - two organisms living together where one inhibits the other and vice versa

• Symbiosis - one microorganism lives on another or inside another

• Commensalism - one benefits and the other is not significantly harmed or helped

Ora eco-niches (niche - term describing the way of life of a species)

1. Supragingival part of teeth

• Microorganism - stretococcus mutans

• Why it inhabits - carbohydrates and biofilm formation

2. Subgingival part of teeth

• Microorganism - Porphyromonas gingivalis

• Why it inhabits - anaerobic conditions

3. Lips and cheeks

• microorganism - Stretococcus mitis

• Why it inhabits - moist and less biofilm

4. Tongue

• Microorganism - stretococcus salivarius

• Why it inhabits - papillary surface provides retention and anaerobic conditions

1. Supragingival part of teeth

• Microorganism - stretococcus mutans

• Why it inhabits - carbohydrates and biofilm formation

2. Subgingival part of teeth

• Microorganism - Porphyromonas gingivalis

• Why it inhabits - anaerobic conditions

3. Lips and cheeks

• microorganism - Stretococcus mitis

• Why it inhabits - moist and less biofilm

4. Tongue

• Microorganism - stretococcus salivarius

• Why it inhabits - papillary surface provides retention and anaerobic conditions

Characteristics of microflora at birth (newborn)

• sterile oral cavity

• rapidly colonised in the first feeding

• Stretococccus salivarius is dominant and make up 98% of total flora until the appearance of teeth

Characteristics of microflora after tooth eruption (6-9 months)

• S. mutans and S. sanguis, these bacteria recquire a non epithelial surface in order to colonise and persist as long as teeth remain

• Other strains of streptococci adhere to cheeks and gums but not the teeth

• Anarobes - eg. actinomyces and lactobacilius

Characteristics of microflora during preschool age

• Children microflora is very similar to adults microflora as their environment and interactions become more diverse