Dental Plaque and Biofilm Overview

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Questions and Answers

Which type of carbohydrate generally has the highest cariogenic effect?

Fructose

Glucose

Sucrose (correct)

Galactose

What is the first step that disaccharides must undergo before they can promote caries?

Enter the bacterial plaque directly

Be converted into monosaccharides (correct)

Be broken down into polysaccharides

Be neutralized by saliva

Which carbohydrate cannot enter the bacterial plaque due to its larger structure?

Starch (correct)

Sucrose

Glucose

Fructose

What type of bacteria are primarily dominant on the tooth surface after 24 hours?

Coccus and filaments Signup and view all the answers

What enzyme is primarily responsible for breaking down starch in the mouth?

Amylase Signup and view all the answers

What occurs to the number of streptococci in the first 12 hours?

It increases constantly Signup and view all the answers

Which of the following sugars is known as 'milk sugar'?

Lactose Signup and view all the answers

Which structure is associated with supragingival plaque?

Plaque where the gingiva does not cover Signup and view all the answers

What effect does the buffering capacity of saliva have on caries formation?

It neutralizes the acid environment Signup and view all the answers

What characterizes subgingival plaque?

It is responsible for periodontal disease Signup and view all the answers

Which of the following is a monosaccharide?

Glucose Signup and view all the answers

What happens to the bacterial composition of plaque as it ages?

Streptococcus mutans increases in number Signup and view all the answers

Why might caries occur in areas that cannot be easily cleaned?

Sticky nutrients remaining in the mouth Signup and view all the answers

What kind of environment do fissure plaque create?

A separate ecological environment for each fissure Signup and view all the answers

When does calculus formation start in fissures?

On the seventh day Signup and view all the answers

Which of the following is true regarding the remodeling phase of plaque?

It's not obvious until plaque is removed Signup and view all the answers

What is the primary role of the pellicle on dental enamel?

Acting as a diffusion barrier Signup and view all the answers

Which type of plaque formation occurs within the first 8 hours?

Young Plaque Signup and view all the answers

Which bacteria are primarily observed in the early soft plaque surface?

S. mitis and S. sanguis Signup and view all the answers

What primarily influences bacterial adhesion to teeth?

The hydrophobic structures of bacteria Signup and view all the answers

At what bacterial concentration is S. sanguis able to hold plaque effectively?

10,000/ml Signup and view all the answers

Which phase of plaque is characterized by rapid bacterial growth after the initial stage?

Mature Plaque Signup and view all the answers

The remodeling phase is known for which specific characteristic?

Stabilization of existing bacteria Signup and view all the answers

In plaque studies, which organism is most commonly found as a premature colony-forming microorganism?

Streptococcus Signup and view all the answers

What factor predominantly affects the cariogenic effect of carbohydrates?

The time carbohydrates remain in the mouth Signup and view all the answers

Why do carbohydrates consumed outside of normal meals have a higher caries-causing effect?

Due to increased salivation during meals Signup and view all the answers

Which carbohydrate is identified as the most cariogenic?

Sucrose Signup and view all the answers

What is a significant consequence of glucans in dental plaque?

They promote bacterial accumulation Signup and view all the answers

Which bacteria is primarily associated with the effect of sucrose on dental caries?

Streptococcus mutans Signup and view all the answers

What was the objective of Stephan's experiment on pH changes after glucose intake?

To observe pH changes in dental plaque Signup and view all the answers

What process happens to sucrose in dental plaque that contributes to its cariogenicity?

It is converted into glucan and fructose Signup and view all the answers

How does a reduction in saliva influence caries formation?

It increases plaque formation Signup and view all the answers

What is the primary role of Streptococcus mutans and Streptococcus sobrinus in dental caries?

They produce acids that lead to tooth decay. Signup and view all the answers

How soon after the appearance of Streptococcus mutans can caries formation generally be observed?

Within 6-24 months Signup and view all the answers

What type of extracellular polysaccharides can Streptococcus mutans form from sucrose?

Glucans and fructans Signup and view all the answers

What role do extracellular polysaccharides (EPS) play in the cariogenicity of Streptococcus mutans?

They create an environment conducive to acid production. Signup and view all the answers

What are glucans and fructans classified as?

Extracellular polysaccharides Signup and view all the answers

Which chemical process characterizes dental caries?

Irreversible loss of material due to organic acids Signup and view all the answers

What is the role of glycosidic bonds in the synthesis of extracellular polysaccharides?

They provide energy for synthesis. Signup and view all the answers

Which of the following describes an irreversible chemical reaction in the context of dental caries?

The decay process cannot be reversed. Signup and view all the answers

What happens to the pH level after a glucose rinse?

It drops below the critical pH within 2-5 minutes. Signup and view all the answers

What is the main characteristic of extracellular polysaccharides (EPS) formed by sucrose?

They primarily consist of insoluble glucans. Signup and view all the answers

How does sucrose affect the concentration of certain ions in dental biofilm?

It decreases the concentration of calcium and fluoride. Signup and view all the answers

What pH level is considered non-cariogenic for foods consumed within 30 minutes?

Above 5.7. Signup and view all the answers

Which statement about lipids in food is true regarding their impact on dental health?

They do not affect decay, but reduce adhesion rates. Signup and view all the answers

What is produced as a final product from the breakdown of proteins in the mouth?

Urea and ammonia. Signup and view all the answers

What is the significance of ammonia in relation to dental health?

It neutralizes acids, providing an advantage against caries. Signup and view all the answers

What does the critical pH level indicate in terms of dental health?

It is the threshold below which demineralization begins. Signup and view all the answers

Study Notes

Dental Plaque

Dental plaque is a deposit of bacteria and bacterial products located on unclean teeth or accumulations on restorations in the mouth.
Plaque formation depends on the position of the teeth, the roughness of tooth surfaces, and personal hygiene.
Plaque formation has three phases: young, mature, and remodeling.

Biofilm

Biofilm is a term used to describe areas where microorganisms settle and reproduce on various surfaces.
It is found on surfaces like water pipes and plays a significant role in hospital infections.
In the oral cavity, microorganisms within the biofilm matrix have different behavior than bacteria floating freely.
One of the important factors enabling microorganisms in the oral flora to remain in this region is their ability to adhere to the tooth surface.

Dental Pellicle

An electron microscope study shows a thin layer of cells without bacteria between the surface of the enamel and bacteria. This thin layer is called the Dental Pellicle.
Dental Pellicle is a protein layer forming on tooth enamel through selective binding of glycoproteins.
This prevents continuous deposition of salivary calcium phosphate.
It protects the tooth from acids produced by microorganisms following consumption of carbohydrates.

Oral Biofilm

The human oral cavity has hundreds of different types of microorganisms, including bacteria, viruses, and fungi.
These live in complex communities, organized into a thin layer called biofilm.
Dental plaque, proteins from saliva, cover tooth surfaces immediately after their cleaning.
Bacterial retention to the film layer occurs due to microfilaments in the cell walls.
As bacteria increases, they communicate and create a community using signal molecules and secreting proteins, polysaccharides, nucleic acids, and other extracellular matrix components.
This matrix acts as the glue of the biofilm.
Microbial communities behave as a single unit, responding to environmental changes.

Caries Microorganisms

Acidogenic bacteria in plaque convert sugar into acids, contributing to tooth demineralization.
Common acidogenic bacteria include Streptococcus, Actinomyces, Lactobacilli, etc.
The composition of the bacterial flora in necrotic soft caries dentin and partly decalcified deep areas of dentin is described in a table.
Specific microbial counts and ranges at various stages are provided.

Caries

Dental caries is the irreversible loss of material caused by organic acids produced in bacterial plaques.
It causes pain and aesthetic issues.
Caries is a complex event involving chemical structures, reaction environments, and tooth structures.
The components of the chemical reaction in caries include reactants, reaction medium, and conditions, and the reaction products.

Acids in the Mouth

Acids occur as a result of oral bacteria activity breaking down carbohydrates.
People with professions requiring constant contact with acids, like in battery factories, labs, etc., are at risk.
Breathing acidic air due to pollution is also a factor.
Some acidic drinks, herbal teas, and alcoholic beverages cause acidification.
Frequent vomiting during pregnancy and chronic alcoholism can lead to gastric juice reflux into the mouth.
Certain drugs, like aspirin and effervescent vitamin tablets, can also cause oral acidification.

Carbohydrates' Role in Caries

Carbohydrates are the initial part of the chemical reaction in caries, leading to organic acid production.
Foods with a high proportion of carbohydrates are major risk factors for caries.
Factors altering carbohydrate-based cariogenicity include their type, the time they remain in the mouth, their texture (hard, sticky, liquid form), and when consumed outside of meal times.

Sucrose and Biofilm

Sucrose is the most cariogenic carbohydrate.
It enables the formation of extracellular and intracellular polysaccharides, especially glucans.
Glucans cause bacteria to adhere to the tooth surface and form the structural biofilm layer.
The presence of sucrose increases oral biofilm porosity and facilitates sugar penetration.

Stephan Curve

Stephan's experiment examined the changes in plaque pH after glucose consumption.
Patients with different levels of caries activity were studied.
An electrode measured the resting pH of plaque and changes resulting from a glucose rinse.
The curves show that the pH drops rapidly after glucose intake, reaching the critical pH level within 2-5 minutes, depending on caries activity.

Factors Affecting Caries-Promoting Properties of Carbohydrates

Different carbohydrates have variable cariogenic effects.
Physical properties like duration of presence in the mouth, texture, solubility, and whether ingested as a meal or snack impact cariogenicity.
Outside of meal consumption, carbohydrates tend to have a higher cariogenic effect.
Individual factors, including saliva amount, flow rate, and tooth anatomy, influence the rate and severity of caries formation.

Types of Plaque

Supragingival plaque is on the gums.
Subgingival plaque is under the gums, and it is a key factor in periodontal diseases.
Plaque in fissures, also called fissure plaque, is very narrow and in occlusal surfaces.

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Description

This quiz explores essential concepts related to dental plaque, biofilm, and dental pellicle. It delves into the formation of dental plaque, its phases, and the role of biofilms in the oral cavity and healthcare settings. Understanding these concepts is crucial for maintaining oral health and preventing infections.