Dental Caries: Microbiology and Hypotheses

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Questions and Answers

What is the primary mechanism by which tooth decay occurs?

Acid formation in dental plaque dissolving the enamel (correct)

Mechanical damage to the enamel by chewing forces

Inflammation of the gums leading to enamel loss

Direct bacterial attack on the enamel

Which of the following hypotheses suggests that the bacteria that initiate caries are not original?

Acid formation hypothesis

Ecologic plaque hypothesis

Specific plaque hypothesis

Non-specific plaque hypothesis (correct)

What is the primary factor that determines the likelihood of tooth decay in an individual?

The genetic predisposition of the individual

The rate of acid formation versus saliva wash (correct)

The type of bacteria present in the plaque

The frequency of sugar consumption

What is the purpose of the Stephan curve?

To measure the pH of the mouth after a glucose shock Signup and view all the answers

Which of the following bacteria is NOT primarily responsible for tooth decay?

Peptostreptococcus Signup and view all the answers

What is the term for the sudden drop in mouth pH that occurs after a glucose shock?

Glucose shock Signup and view all the answers

Which of the following is a characteristic of tooth decay?

It is a progressive disease performed entirely by bacteria Signup and view all the answers

What is the term for the balance of microflora in the mouth that can lead to tooth decay?

Permanent microflora balance deterioration Signup and view all the answers

Which of the following bacteria is NOT a dominant species associated with caries?

Escherichia Signup and view all the answers

What is the primary reason why antibiotic chewing gums are not effective in preventing tooth decay?

They destroy oral flora Signup and view all the answers

What is the best method for preventing tooth decay?

Balanced diet, removal of plaques, and hygiene education Signup and view all the answers

Why may people with bad oral hygiene have less dental caries?

Due to IgA against carcinogenic bacteria in saliva Signup and view all the answers

What is the primary mechanism by which anatomical malformations affect dental caries?

They reduce the washing effect of saliva Signup and view all the answers

Why is oral hygiene important in preventing tooth decay?

It removes plaque and acids Signup and view all the answers

What is the primary function of bacteria in the process of caries formation?

To convert CHs to acids Signup and view all the answers

What is the main component of tooth enamel?

Calcium phosphate Signup and view all the answers

What is the result of acid dissolution of calcium salts in tooth enamel?

Demineralization of enamel tissue Signup and view all the answers

What type of bacteria are commonly found in individuals with caries?

All of the above Signup and view all the answers

What is the characteristic of the decay process in dentin tissue?

It is more progressive than enamel decay Signup and view all the answers

What is the result of the decomposition of organic matrix by bacteria?

Formation of black colored caries Signup and view all the answers

What is the primary difference between the flora of non-caries and caries individuals?

Presence of Actinomyces spp Signup and view all the answers

What is the role of cavitation in the decay process?

It allows for the entry of bacteria into the microcavities of demineralized enamel Signup and view all the answers

Study Notes

Tooth Decay

Tooth decay is a progressive disease caused entirely by bacteria
It is a chronic infection disease that can occur in both poor and rural areas, as well as in civilized societies
Tooth decay occurs when the enamel is dissolved by acids produced by bacteria in the dental plaque

Caries Hypotheses

Specific plaque hypothesis: S.mutans and S.sobrinus initiate caries
Non-specific plaque hypothesis: the bacteria that start caries are not original
Ecologic plaque hypothesis: permanent microflora balance deterioration leads to caries

Acid Formation in Dental Plaque

Acid formation depends on the variety of bacteria in the plaque
Acid and alcohols are formed from carbohydrates
Saliva dilutes, washes, and buffers acid, but tooth decay occurs when acid-producing mechanisms overcome acid removal mechanisms

Glucose Shock

Mouth pH drops due to 10% glucose solution given by healthy individuals and rinsing their mouths for 10 sec
The Stephan curve is obtained by measuring the pH of the mouth at 30 sec intervals following a glucose shock
The curve is different for each human, dental plaque, and cryogenic bacterium

Demineralization

Bacteria convert carbohydrates into acids, which create caries
pH of the environment drops, and tooth enamel, a calcified tissue, is dissolved
Acid medium dissolves Ca salts, and the organic matrix (collagen) remains from demineralized enamel tissue (appearing white in color)

Cavitation

In the later stages of decay, bacteria enter the microcavities of the demineralized enamel
First, Laktobacilli and Streptococci bacteria enter, followed by increased acid production, making enamel repair impossible
Event is irreversible, and dentin decay is more progressive

Decay-Forming Bacteria

In children aged 1.5 to 7 years, non-caries individuals have S.mitis, S.oralis, S.sanguinis, and S.parasanguinis, while individuals with caries have Actinomyces spp, Lactobacillus spp, and S.mutans
In deep caries of young permanent teeth, S.mitis, S.pneumoniae, S.infantis, and other bacteria are present
The most dominant bacteria in caries are Lactobacillus, Veillonella, Bifidobacterium, Propionibacterium, Actinomyces, Atopobium, and S.mutans

Prevention of Dental Caries

Protection from tooth decay is possible with removal of plaque and acids by toothbrush
Using antiseptic and local antibiotics is incorrect
Best method: Balanced diet, removal of plaques, and hygiene education

Dental Caries Immunology

Oral hygiene proves that tooth decay is not a genetic disease
Bacteria that cause caries are not genetically transmitted, they are transmitted from the oral environment and multiply
Familial food consumption habits play a role in tooth decay
People with bad oral hygiene may have less dental caries due to IgA against carcinogenic bacteria in saliva and effective non-specific immunity

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Description

This quiz covers the microbiology of tooth decay, its causes, and hypotheses. It explores the role of bacteria in tooth decay and the different hypotheses surrounding the disease.