The Mouth as a Microbial Habitat

🦠 Section 3 The Mouth as a Microbial Habitat

What makes the mouth a unique microbial habitat?

It provides different surfaces, nutrients, and conditions that support diverse microorganisms.

What are the main ecological surfaces in the oral cavity?

Mucosal surfaces, teeth, saliva, gingival crevicular fluid, and prosthetic or implant surfaces.

What are mucosal surfaces?

The soft, moist linings of the mouth such as the cheeks, tongue, and palate.

What kind of microorganisms live on mucosal surfaces?

Mostly bacteria that can attach to epithelial cells or exist in biofilms.

Why do microorganisms prefer mucosal surfaces?

Because they provide moisture, nutrients, and warmth.

What are teeth considered in microbiology?

Hard, non-shedding surfaces where biofilm (plaque) forms easily.

Why are teeth important for microbial colonization?

They provide a stable surface for bacteria to attach and form plaque.

What is saliva’s role in oral microbiology?

It cleanses the mouth, contains enzymes, and provides nutrients for some bacteria.

What enzymes are found in saliva that affect microorganisms?

Lysozyme, lactoferrin, and peroxidase.

What is gingival crevicular fluid (GCF)?

A fluid that seeps from the gingival sulcus, containing immune cells and nutrients.

Why is GCF important in the oral cavity?

It defends against pathogens but can also provide nutrients for bacteria.

What are implants and prosthetic devices in dentistry?

Artificial materials such as crowns, bridges, or dentures.

Why do implants and prosthetic devices affect oral microbiota?

They provide new surfaces where biofilms can form.

What factors affect microbial growth in the oral cavity?

pH, temperature, oxygen levels, saliva flow, and oral hygiene.

What is the normal pH of the mouth?

Around 6.7 to 7.3, slightly neutral.

How does pH influence bacterial growth?

Acidic environments favor acid-tolerant bacteria like Streptococcus mutans.

What happens when the pH drops in the mouth?

Demineralization of enamel and caries development.

What temperature supports oral bacterial growth?

Around 35–37°C, which is normal body temperature.

How does periodontal disease affect microbial growth?

It creates deep pockets that trap bacteria and reduce oxygen, favoring anaerobes.

How do caries affect microbial growth?

They increase the number of acid-producing bacteria.

What is a biofilm?

A structured community of microorganisms attached to a surface and surrounded by a protective matrix.

Why are biofilms significant in dentistry?

They cause plaque-related diseases like caries and periodontitis.

What happens when biofilms are not disrupted?

They mature and become more resistant to antimicrobials and immune defenses.

What daily habit helps control biofilms?

Brushing and flossing.