Dental Plaque: Structure and Formation

Summary

The oral cavity hosts a complex bacterial ecosystem that coexists harmoniously with the host. Salivary proteins form a protective pellicle on surfaces, aiding lubrication and bacterial adherence. Dental plaque, a biofilm of bacteria, epithelial cells, and salivary proteins, can lead to calculus and dental caries if oral hygiene is neglected. Plaque's diverse microflora, including bacteria, yeasts, and viruses, thrives in a matrix of organic and inorganic materials. Its structure supports bacterial growth, potentially causing periodontal diseases if not properly managed.

Takeaways

• 🌿 The oral cavity hosts a diverse microbial community, primarily bacteria, which coexist harmoniously with the host.
• 🛡️ Salivary proteins form a protective lubricating layer known as the salivary pellicle on oral surfaces, aiding in lubrication and bacterial adherence.
• 🦠 Dental plaque is a complex biofilm composed of bacterial communities, epithelial cells, and salivary proteins, firmly attaching to tooth surfaces.
• 📈 If oral hygiene is neglected, teeth can accumulate bacterial communities that form dental plaque, leading to potential dental issues.
• 🔍 Dental plaque can be classified as supra-gingival or sub-gingival, with the latter posing a greater risk to periodontal health.
• 🌐 The mature plaque ecosystem contains over 500 distinct microbial species, including bacteria, yeasts, and viruses.
• 🌀 Plaque acts as a micro-environment with circulatory channels that facilitate the movement of nutrients and waste, supporting bacterial growth.
• 🔬 The organic and inorganic components of plaque make up 20-30% of its mass, with salivary glycoproteins and minerals like calcium and phosphorus being key constituents.
• 🕒 Plaque formation begins with the rapid development of an acquired pellicle, followed by bacterial colonization and growth.
• 🌱 Initial bacterial colonizers include Streptococcus and Actinomyces species, which adhere to the pellicle and proliferate, setting the stage for plaque development.
• 🌱 As plaque matures, it creates an anaerobic environment that supports the growth of anaerobic bacteria, potentially leading to gingival inflammation and periodontal disease.

Q & A

What is the primary type of microorganism found in the oral cavity?

Bacteria are the predominant microorganisms found in the oral cavity, where they form distinct microbial communities on mucosal surfaces and teeth.

How does the salivary pellicle contribute to the oral environment?

The salivary pellicle is a lubricating layer formed by salivary proteins on surfaces in the oral cavity. It aids in lubrication and provides binding sites for bacteria adherence.

What is the role of the continuous shedding of epithelial cells in the oral cavity?

The continuous shedding of epithelial cells prevents excessive accumulation of bacterial deposits, thus maintaining a balance in the oral environment.

Why do teeth promote bacterial accumulation if oral hygiene is not maintained?

Teeth provide non-shedding surfaces that can lead to the accumulation of bacterial communities, particularly if oral hygiene practices are inadequate.

What is dental plaque and where does it typically accumulate on teeth?

Dental plaque is a yellowish-white biofilm composed mainly of bacterial communities, exfoliated epithelial cells, and salivary proteins. It typically accumulates in the gingival thirds of the tooth surface.

How is dental plaque classified based on its site of deposition?

Dental plaque can be classified as supra-gingival plaque, which is above the gumline, and sub-gingival plaque, which is below the gumline and can also be associated with sulcular tissue.

What are the potential consequences of tissue-associated sub-gingival plaque?

Tissue-associated sub-gingival plaque can be detrimental to periodontal tissues, contributing to periodontitis, a disease that affects the gums and supporting structures of the teeth.

How diverse is the microbial community within mature dental plaque?

Mature dental plaque is a diverse biofilm with at least 500 distinct microbial species, including bacteria, yeasts, and viruses.

What are the primary components of the organic and inorganic portions of the plaque matrix?

The organic portion of the plaque matrix is mainly composed of salivary glycoproteins, extracellular polysaccharides, and some lipid material. The inorganic portion is primarily made up of calcium and phosphorus, along with small amounts of sodium, potassium, and fluoride.

How does the process of bacterial colonization begin on the tooth surface?

Bacterial colonization begins with the formation of a thin coating called the acquired or salivary pellicle, which is a coating of salivary proteins that forms within seconds to minutes after the tooth surface is cleansed.

What is the significance of co-aggregation in the development of dental plaque?

Co-aggregation is a process where different types of bacteria adhere to each other, forming complex structures like 'corn-cob' arrangements. This interaction is significant as it contributes to the development of a mature plaque biofilm with a diverse microbial community.

Outlines

00:00

🦠 Oral Cavity's Microbial Balance and Dental Plaque Formation

The oral cavity is a complex ecosystem hosting a diverse range of microorganisms, predominantly bacteria, which coexist harmoniously with the host. Salivary proteins form a lubricating layer known as the salivary pellicle on all oral surfaces, aiding in lubrication and providing binding sites for bacteria. The continuous shedding of mucosal epithelial cells prevents excessive bacterial accumulation, unlike teeth which, if not properly maintained, can lead to the formation of dental plaque. Dental plaque is a biofilm consisting mainly of bacterial communities, exfoliated epithelial cells, and salivary proteins, adhering to tooth surfaces and potentially causing periodontal issues. It can be classified as supra-gingival or sub-gingival, with the latter posing a greater risk to periodontal health. The mature plaque is a diverse biofilm with at least 500 distinct microbial species, including bacteria, yeasts, and viruses, all housed in a matrix of organic and inorganic materials. The organic matrix includes salivary glycoproteins and extracellular polysaccharides, while the inorganic portion is primarily composed of calcium and phosphorus. Plaque formation initiates with the rapid formation of the acquired pellicle, followed by colonization by initial bacterial species like Streptococcus and Actinomyces, which adhere through bacterial proteins called adhesins.

05:01

🌱 Development and Impact of Dental Plaque on Oral Health

Dental plaque development involves the growth of bacteria, which initially adhere to the tooth surface and then expand laterally, forming columnar structures. The initial colonizers, being facultative anaerobes, deplete oxygen, creating an anaerobic environment conducive to the growth of anaerobic bacteria. This leads to the colonization of gram-negative rods and filaments, such as Prevotella intermedia and Porphyromonas gingivalis, which interact with the initial colonizers through a process known as co-aggregation, forming 'corn-cob' like structures. As plaque accumulates, it can extend beyond the gingival margin, causing inflammation and deepening of the gingival sulcus. The sub-gingival plaque, similar in structure to supra-gingival plaque but with additional spirochetes, feeds on nutrients from periodontal tissues and blood, leading to tissue breakdown and increased plaque microflora. This process can result in the progression of periodontal disease.

Keywords

💡Oral cavity

The oral cavity is the space within the mouth that contains the teeth, tongue, and other structures. It is the primary site for the diverse microbial flora discussed in the video. The oral cavity provides a habitat for these microorganisms, which can be both beneficial and harmful to oral health, depending on their balance and interaction with the host.

💡Microbial flora

Microbial flora refers to the community of microorganisms that naturally inhabit a particular environment. In the context of the oral cavity, this includes a variety of bacteria, yeasts, and viruses that live in harmony with the host, as long as their growth and proliferation are maintained in a balanced state.

💡Salivary pellicle

The salivary pellicle is a thin, lubricating layer formed by salivary proteins on the surfaces of the oral cavity, including teeth. It serves a dual purpose: it lubricates the mucosal surfaces and provides binding sites for bacteria, which is crucial for the initial stages of dental plaque formation.

💡Dental plaque

Dental plaque is a yellowish-white biofilm that forms on teeth and is composed mainly of bacterial communities, exfoliated epithelial cells, and salivary proteins. It is a key focus of the video, as it can lead to dental caries and periodontal diseases if not properly managed through oral hygiene practices.

💡Biofilms

Biofilms are communities of microorganisms that adhere to surfaces and are encased in a matrix of extracellular polymeric substances. In the oral cavity, biofilms are commonly known as dental plaque, which can accumulate and cause dental problems if not removed through regular cleaning.

💡Gingival sulcus

The gingival sulcus, also known as the gingival crevice, is the space between the gum and the tooth. It is mentioned in the video as a site where sub-gingival plaque can accumulate, leading to inflammation and potentially periodontal disease.

💡Acquired pellicle

The acquired pellicle is the initial layer of salivary proteins that forms on a cleansed tooth surface within seconds to minutes. It is significant because it serves as the foundation for bacterial colonization, which eventually leads to the development of dental plaque.

💡Adhesins

Adhesins are bacterial proteins that facilitate the attachment of bacteria to surfaces, such as the acquired pellicle on teeth. They play a critical role in the formation of dental plaque by enabling bacteria to adhere and accumulate on tooth surfaces.

💡Co-aggregation

Co-aggregation is the process by which different types of bacteria interact and adhere to one another, forming complex structures within the dental plaque. The video describes this process as essential for the development of a mature plaque community, with examples like the 'corn-cob' structures.

💡Anaerobic bacteria

Anaerobic bacteria are microorganisms that thrive in environments with little to no oxygen. In the oral cavity, the growth of facultative anaerobic bacteria can deplete oxygen, creating conditions suitable for the proliferation of anaerobic species, which can contribute to periodontal disease.

💡Periodontitis

Periodontitis is a severe gum infection that can lead to the destruction of the soft tissue and bone that support the teeth. The video discusses how the accumulation of sub-gingival plaque, particularly tissue-associated plaque, can contribute to the development of periodontitis.

Highlights

The oral cavity hosts a diverse microbial flora, predominantly bacteria, forming distinct communities on mucosal surfaces and teeth.

A harmonious relationship exists between the host and the microbial community, with a delicate balance in the growth of micro-organisms.

Salivary proteins form the salivary pellicle, a lubricating layer that also provides binding sites for bacteria adherence.

Mucosal surfaces shed epithelial cells continuously, preventing excessive bacterial accumulation.

Teeth, being non-shedding surfaces, promote bacterial accumulation if oral hygiene is neglected.

Dental plaque is a biofilm composed mainly of bacterial communities, exfoliated epithelial cells, and salivary proteins.

Dental plaque accumulation is influenced by tooth surface characteristics and oral hygiene practices.

Sub-gingival plaque can be detrimental to periodontal tissues, potentially leading to periodontitis.

Mature plaque contains a diverse range of microflora, including bacteria, yeasts, and viruses.

The plaque matrix is composed of organic and inorganic materials derived from saliva, bacteria, and gingival crevicular fluid.

Plaque has primitive circulatory channels that facilitate the movement of nutrients and waste products.

The organic portion of the plaque matrix includes salivary glycoproteins, extracellular polysaccharides, and lipids.

The inorganic portion of the plaque matrix is primarily composed of calcium and phosphorus, along with trace elements.

Plaque formation begins with the rapid formation of the acquired pellicle, a coating of salivary proteins on the tooth surface.

Initial bacterial colonizers include Streptococcus species and Actinomyces species, which adhere to the pellicle.

Bacterial adhesins bind to proline-rich proteins in the pellicle, facilitating stronger attachment over time.

Streptococcus species produce extracellular polysaccharides that aid in bacterial adhesion and provide energy.

As plaque matures, it supports the growth of anaerobic bacteria, leading to a shift in the microbial community.

Sub-gingival plaque can lead to gingival inflammation and deepening of the gingival sulcus due to its anaerobic environment.

The structural similarity between supra-gingival and sub-gingival plaques, with the latter potentially harboring more spirochetes.

Transcripts

The oral cavity comprises of a diverse variety of microbial flora,

of which bacteria are predominant

and are housed as distinct microbial communities on mucosal surfaces as well as

on teeth.

The host and the microbial community maintain a harmonious relationship and there is a delicate

balance maintained as far as the growth and proliferation of these micro-organisms are

concerned.

Salivary proteins help form a lubricating layer called the salivary pellicle

on all surfaces in the oral cavity.

While this helps in lubrication of the mucosal surfaces

it also provides for binding sites

that help in adherence of bacteria.

Luckily, epithelial cells of the mucosal surfaces are continuously shed and this prevents an

excessive accumulation or build-up of bacterial deposits.

The teeth however provide for non-shedding surfaces and promote accumulation of bacterial

communities if oral hygiene is not well maintained.

Micro-organisms, primarily bacteria thrive and proliferate in soft deposits or biofilms

formed on teeth.

These soft deposits are called dental plaque.

Dental plaque is a yellowish-white deposit or biofilm that comprises predominantly of

bacterial communities in a matrix of exfoliated epithelial cells and salivary proteins.

It attaches tenaciously to the surfaces of teeth as well as any prostheses or appliances

in the oral cavity.

Dental plaque usually accumulates in the gingival thirds of the tooth surface.

This is because formation of initial plaque in the coronal 2/3rds can be disrupted by

movement of mucosal tissues over the teeth during mastication.

Pits and fissures in teeth, areas around malaligned teeth and overhanging restorations may also

favour its accumulation.

Dental plaque according to its site of deposition can be classified

as supra-gingival and sub-gingival plaque.

Sub-gingival plaque apart from being tooth associated can also be associated with the

sulcular tissue.

While supra-gingival and tooth associated sub-gingival plaque could contribute to calculus

formation and dental caries,

tissue associated sub-gingival plaque could be detrimental to the periodontal

tissues contributing to periodontitis.

The mature plaque is a biofilm with diverse microbial colonies

having at least 500 distinct microbial species.

Though predominantly bacterial, the microflora also harbours yeasts and viruses.

These micro-organisms are housed in a matrix consisting of organic and inorganic materials

derived from the saliva, bacteria and the gingival crevicular fluid.

In fact the plaque behaves like an organism by also having primitive circulatory channels

within the mass of the plaque matrix.

These channels help in movement of nutrition and waste products in and out of the plaque

mass.

This provides for a micro-environment for the bacteria to thrive and proliferate.

Organic and inorganic portion of the plaque matrix comprise around 20-30% of the plaque mass.

Organic portion of the matrix comprises of salivary glycoproteins, extracellular polysaccharides

like glucans and fructans produced by bacteria as well as a little lipid material.

Calcium and phosphorus form the bulk of the inorganic portion together with small amounts

of sodium, potassium and fluoride.

Plaque formation starts with the formation of a thin coating called the acquired or salivary pellicle

on the surface of the tooth.

Acquired pellicle is a coating of salivary proteins, predominantly glycoproteins and

is formed within seconds to minutes after the tooth surface is cleansed.

Apart from being derived from salivary proteins, it may also have components derived from the

crevicular fluid.

After a few hours of pellicle formation, bacteria start to colonize.

The initial colonizers are Gram positive facultative anaerobic cocci and rods, usually Streptococcus

species and Actinomyces species respectively.

The bacterial colonization is, initially purely physical and is a reversible attachment.

With time, the attachment becomes stronger and bacteria firmly adhere to the pellicle.

This attachment is facilitated by binding of bacterial proteins called adhesins to proline

rich proteins in the pellicle.

The initial colonizers primarily derive nutrition from salivary glycoproteins and simple sugars

and continue to divide and proliferate forming microbial colonies.

Streptococcus species produce extra-cellular polysaccharides like glucans and fructans

that help in both adhesion of more bacteria as well as providing an energy source for

the bacterial colonies.

The bacteria continue to grow laterally to cover the tooth surface and then begin to

grow away from the tooth as columnar microbial colonies.

The initial colonizers being facultative anaerobes begin to deplete the oxygen in the micro-environment

with their growth and pave way for the growth of anaerobic bacteria.

As the environment becomes more anaerobic,

gram -ve rods and filaments begin to colonize at the outer surface of the plaque mass.

These include Prevotella intermedia, Capnocytophaga species, Fusobacterium nucleatum and Porphyromonas

gingivalis.

These organisms adhere to the bacteria already on the plaque mass via receptors and interact

with the primary colonizers, a process called co-aggregation.

A classic example of co-aggregation is the presence of “corn-cob” like structures.

These corn-cob structured interactions comprise of a central gram negative organism like F.nucleatum

and outer bacterial cocci attached along the central rod bacteria.

As the plaque mass accumulates supra-gingivally, it begins to cover the tooth surface and grow

beyond the gingival margin.

This may lead to the gingival tissues getting inflamed causing a deepening of the gingival

sulcus.

The environment in the gingival sulcus becomes anaerobic and nutrition for the bacteria is

derived primarily from the periodontal tissues and blood.

This leads to tissue breakdown, further deepening pockets and increasing plaque microflora.

The sub-gingival plaque structurally resembles the supra-gingival plaque and may also harbour

more spirochetes in addition to the same gram negative bacterial community present in the

supra-gingival plaque.