Dental Caries Lecture Notes

These flashcards cover the definition, etiology, host factors, bacterial mechanisms, and pathology (enamel/dentin/root) of dental caries based on the provided lecture transcript.

How is dental caries defined in the transcript?

A localized microbial disease affecting post-eruptive hard tooth structures, characterized by demineralization of the inorganic portion and destruction of the organic substance of the tooth.

When does caries occur in relation to the dynamic process of mineralization?

Caries occurs when demineralization is greater than remineralization.

What are the four primary factors in the etiology of dental caries?

1. Host (tooth and saliva), 2. Substrate (fermentable carbohydrates), 3. Agent (bacteria), and 4. Time.

Why do posterior teeth show more caries than anterior teeth?

Due to more pits and fissures and the difficulty of cleaning.

What is the maximum recommended amount of fluoride in water to avoid fluorosis?

$1.5\,\text{parts per million (ppm)}$.

How does fluoride increase enamel resistance to demineralization?

Fluoride replaces the hydroxyl group in hydroxyapatite to form fluorapatite, which is less soluble in acids.

Why do patients with Down syndrome have a low caries index?

They have teeth spacing due to true generalized microdontia, shallow fissures, higher salivary $\text{PH}$, and sialorrhea.

What is the function of Lysozyme in saliva?

It causes lysis to the bacterial cell wall (bactericidal effect).

Which carbohydrate is considered the 'arch criminal' of dental caries?

Sucrose (a disaccharide).

What were the conclusions of the Vipeholm experiment (1945-1953)?

Increased sugar consumption increases caries activity; risk is greater if sugar is sticky or consumed between meals (frequency and texture are more effective than total amount).

What did the Miller experiment (1890) prove?

Microorganisms are essential in the caries process, as only the non-boiled test tube with bacteria showed caries.

Which specific bacteria produced both smooth surface and pit and fissure caries in Orland experiments?

Streptococcus mutans.

What is the definition of a 'gnotobiote'?

An animal in which all the life forms (bacteria, virus, etc.) are known.

How does Dextran function within dental plaque?

It acts as an adhesive sticky substance for attachment, provides bulk to the plaque, and serves as a barrier to acid diffusion and entry of salivary buffers.

What is the thickness of the acquired enamel pellicle?

$0.1$ to $1.0\,\mu\text{m}$.

What is the 'climax community' or mature community in plaque formation?

A stage involving distinctive bacterial aggregations referred to as 'corn on the cobs' (lactobacilli, actinomyces naeslundii).

What is the 'critical PH' according to the Stephan experiment?

The $\text{PH}$ level ($5.5$) at which demineralization starts.

What are the four zones of early enamel caries seen in ground sections?

1. Translucent zone (advancing front), 2. Dark zone, 3. Body of the lesion (most demineralized), and 4. Surface zone (most mineralized).

What causes the 'dark zone' in enamel caries to appear dark?

The presence of many tiny pores that are unable to absorb quinoline solution and do not transmit polarized light.

What characterizes 'infected dentin' (the superficial zone)?

Bacteria are present, collagen is irreversibly denatured, and it is not remineralizable (should be removed).

What is 'Sclerotic dentin'?

Dentine with higher mineral content due to continuous deposition of calcium salts within the tubules to protect deeper dentine and pulp from acid and bacteria.

What are 'liquefaction foci' in dentin caries?

Irregular cavities formed when bacteria-filled distended tubule 'beads' coalesce longitudinally.

Which bacteria are primarily involved in root caries?

Actinomyces viscosus, Streptococcus mutans, and lactobacilli.

Describe the Proteolytic Theory of dental caries.

It suggests the first attack is by proteolytic bacteria on the enamel protein matrix, providing a pathway for invasion and producing sulfuric acid to demineralize enamel.

Why is the Proteolysis Chelation Theory rejected?

It does not explain the role of sugars, proteolytic bacteria failed to produce caries in gnotobiotes, and it wrongly suggests caries occurs in a neutral medium.