Microbial Biofilms and Dental Caries: Structure, Role, and Pathogenesis 낱말 카드

What is the oral microbiome?

The oral microbiome refers to the diverse community of microorganisms, including bacteria, fungi, and viruses, that inhabit the oral cavity.

How many total genomes have been identified in the human oral microbiome?

Over 70,000 total genomes have been identified.

Approximately how many species of bacteria are found in the human oral microbiome?

Approximately 3,400 species of bacteria.

What is a microbial biofilm?

A microbial biofilm is an aggregate of microorganisms in which cells are embedded in a self-produced matrix.

What is dental plaque?

Dental plaque is a biofilm that forms on the surfaces of teeth, consisting of bacteria and their extracellular matrix.

What factors can cause a health-associated dental biofilm to shift towards a cariogenic community?

Dietary carbohydrate, microbial metabolism, and biofilm structure can lead to this shift.

What is the average number of different species detectable in an individual's oral microbiome at a given time?

Typically, 100-300 different species.

What factors influence the composition of oral microbial communities?

Factors include oral site, dentition/age, salivary flow, pH, buffering capacity, diet, and oral hygiene.

How does the size of microbial cells compare to human epithelial cells?

Most bacterial cells are 1-2 microns in size, while human epithelial cells are approximately 65 microns.

What is the significance of microbial aggregation in biofilms?

Microbial aggregation allows for the formation of complex structures necessary for growth and persistence.

What are extracellular polymeric substances (EPS)?

EPS are substances produced by biofilm cells that allow them to adhere to each other and to surfaces.

What components can EPS be composed of?

EPS can include DNA, proteins, and polysaccharides.

What percentage of human microbial infections are linked to biofilms?

60-80% of all human microbial infections are linked to biofilms.

What happens during the biofilm formation cycle?

The cycle begins with cell attachment, followed by biofilm growth, and eventually dispersal or detachment.

How do biofilms vary in frequency among patients?

Biofilms occur with varying frequencies in clinically healthy patients and those with active infections or underlying conditions.

What role does the host's disease state play in biofilm structure?

Certain structures are more commonly observed in health, while others are found in disease, influenced by the abundance of specific microbes.

What is biogeography in the context of oral microbiomes?

Biogeography refers to the distinct spatial structure of microbial communities based on their specific niches in the oral cavity.

What is the relationship between microbial size and biofilm formation?

The small size of microbial cells allows them to aggregate and form structures larger than individual host cells.

What is the impact of dietary carbohydrates on dental biofilms?

Dietary carbohydrates can contribute to the shift of a health-associated biofilm to a cariogenic community, leading to enamel demineralization.

What is the source of the information on microbial biofilms in dental caries?

The information is sourced from various studies, including Giordano-Kelhoffer et al., 2022, and Baker et al., 2024.

How do oral microbial communities change over time?

They change throughout life and in response to local environmental conditions.

What is the significance of the genetic make-up of microbes in the oral cavity?

The genetic make-up allows microbes to specialize and adapt to their specific niches within the oral cavity.

What is the biofilm matrix composed of?

Extracellular polymeric substances (EPS) produced by cells within the biofilm.

What is the primary function of the biofilm matrix?

It provides structural support and protects cells from environmental forces.

What is the salivary pellicle?

A coating on the enamel surface made of host and bacterial proteins, DNA, and polysaccharides.

What are 'pioneer colonizers' in oral biofilms?

The first bacterial species to adhere to the salivary pellicle, primarily Streptococcus species.

What role do 'bridging species' play in biofilm formation?

They provide binding sites for additional species after pioneer colonizers attach.

What happens to the microbial composition of oral biofilms when the environment is perturbed?

There can be a shift leading to the loss of the 'health-associated' community and emergence of odontopathogens.

What advances have allowed profiling of microbial communities in dental health?

Sequencing technologies such as amplicon (16S) and shotgun (metagenomics).

What is the significance of Streptococcus mutans in dental caries?

It is consistently recovered from carious lesions and is shown to initiate decay.

What enzymes does Streptococcus mutans produce to aid biofilm formation?

Glucosyltransferases (GTFs) that convert carbohydrates into glucans.

How do glucans contribute to biofilm structure?

They provide attachment sites for bacteria and encase cells within a biofilm matrix.

What is the effect of sucrose concentration on glucan production by S. mutans?

Higher sucrose concentrations lead to increased glucan production, facilitating microcolony formation.

What are rotund microcolonies and their role in caries?

Structures formed by S. mutans that trap acid, leading to demineralization of enamel.

What metabolic products does S. mutans produce from carbohydrates?

Organic acids such as lactate, acetate, ethanol, and formate.

How does S. mutans tolerate acidic environments compared to other oral bacteria?

It has mechanisms that allow it to ferment at pH values < 5.5, unlike other Streptococcus species.

What is the cariogenic cycle?

A process involving the formation of biofilms, acid production, and demineralization of enamel leading to caries.

What happens to other oral bacteria in low pH environments?

They are killed off, allowing cariogenic organisms like S. mutans to thrive.

What are health-associated microbes?

Members of oral biofilms that do not cause disease and may promote health.

What are odontopathogens?

Pathogenic microorganisms that can emerge when the health-associated community is disrupted.

What is the role of saliva in oral biofilms?

Saliva acts as a buffer but may not neutralize acids trapped within microcolonies.

What is the significance of glucan accumulation in biofilms?

It aids in the formation of microcolonies and enhances bacterial attachment.

What are the characteristics of Streptococcus mutans?

It is a Gram-positive, non-motile, facultative anaerobe that forms chains.

What is the impact of dietary carbohydrates on S. mutans?

S. mutans rapidly metabolizes carbohydrates, contributing to acid production and caries development.

What is the relationship between biofilm structure and caries development?

Biofilm structure traps acids, leading to a decrease in pH and promoting demineralization.

What are interspecies interactions in dental biofilms?

Interactions between different bacterial species within biofilms that can influence health or disease.