Distribution, Development, and Benefits of the Oral Microbiota

🌱 Section 5 Distribution, Development, and Benefits of the Oral Microbiota

Where is the fetus’s mouth sterile?

In the womb.

When does microbial colonization begin?

At birth.

Where do babies acquire their first oral microbes?

Mostly from the mother.

How does delivery method affect oral microbiota?

Vaginal delivery gives microbiota similar to the mother’s vaginal community; C-section gives microbiota similar to skin.

How does feeding type affect infant oral microbiota?

Breastfed babies have more Lactobacilli, which can inhibit S. mutans and C. albicans.

What is vertical transmission?

Transfer of microbes from mother to child.

What is horizontal transmission?

Transfer of microbes between individuals, e.g., spouses.

What are pioneer species?

The first microbes to colonize a surface in the mouth.

What is microbial succession?

Gradual replacement of pioneer species by other microbes.

What is allogenic succession?

Microbial changes caused by non-microbial factors.

What is autogenic succession?

Microbial changes caused by other microbes themselves.

How does tooth eruption affect microbiota?

Increases spirochetes and black-pigmented anaerobes.

What is microbial homeostasis?

Stable balance of oral microbiota over time.

Why is sampling oral microbiota challenging?

Microbes are in biofilms, are hard to reach, and some are unculturable.

How can oral mucosa be sampled?

Swabbing, scraping, or direct impression.

How can saliva be collected?

Expectoration, either unstimulated or stimulated.

How is plaque sampled?

Using dental instruments, floss, or acrylic strips.

Why is subgingival plaque difficult to sample?

Inaccessibility and anaerobic environment.

How should samples be transported?

Quickly, in reducing transport fluids to preserve anaerobes.

What is the purpose of dispersing samples?

To separate bacteria for accurate counting and culturing.

What is culture-based identification?

Growing microbes on selective or non-selective media.

What is colony counting?

Counting visible microbial colonies to estimate numbers in the sample.

What are limitations of microscopy?

Cannot identify most pathogens by shape alone; advanced techniques like confocal microscopy needed.

What are in situ models?

Devices placed in the mouth to study microbial colonization on surfaces.

Which microbes are common on lips?

Facultative anaerobic Streptococci and sometimes Candida albicans.

Which microbes are common on cheeks?

Mostly Streptococci.

Which microbes dominate the tongue?

Streptococci, with low levels of lactobacilli, yeasts, fusobacteria, and spirochetes.

What is dental plaque?

Microbial biofilm on teeth.

What is denture plaque?

Microbial biofilm on dentures.

What is supragingival plaque?

Plaque above the gum line.

What is subgingival plaque?

Plaque below the gum line.

Which bacteria dominate plaque?

Gram-positive rods and filaments (Actinomyces), obligate anaerobes, and others.

Does saliva have its own microbiota?

No, saliva mainly carries microbes from other surfaces.

Why is saliva useful clinically?

Microbial counts can indicate caries risk.

What is colonization resistance?

Ability of resident microbes to prevent colonization by pathogens.

How do microbes provide colonization resistance?

Compete for nutrients, occupy attachment sites, produce inhibitory substances.

What are prebiotics?

Molecules that stimulate beneficial microbial growth.

What are probiotics?

Live beneficial microbes that can be supplemented.

How do oral microbes help nitrate metabolism?

Reduce dietary nitrate to nitrite, affecting blood pressure and antimicrobial defense.

How do beneficial oral microbes interact with host cells?

Stimulate immune pathways, promote wound healing, enhance mucin production, and support epithelial health.