Biochemistry and Histopathology of Dental Caries: Key Concepts and Zones 낱말 카드

What are the key factors in the development of dental caries?

Acid-producing bacteria, fermentable carbohydrates, host factors including teeth and saliva, and time.

What is the role of the oral biofilm ecosystem in dental caries?

It is a structured community of microorganisms that can shift from a healthy to a cariogenic state based on diet and environmental factors.

What is eubiosis in the context of oral biofilms?

A healthy biofilm characterized by a diverse and stable microbial community.

What is dysbiosis?

An unbalanced biofilm that favors pathogenic bacteria, often due to frequent sugar intake.

What happens to plaque pH after sugar intake according to the Stephan Curve?

Plaque pH drops within 5 minutes and slowly recovers over 20-40 minutes.

What are extracellular polymeric substances (EPS) and their function?

Produced by S. mutans, EPS serve as a structural scaffold, trap acids, and act as a nutrient reserve.

What is the process of tooth demineralization?

It involves the dissolution of hydroxyapatite due to protons from acids produced by bacteria.

What conditions favor tooth remineralization?

When saliva is supersaturated with minerals and at neutral/alkaline pH, especially with fluoride present.

What are the four zones of carious lesions as per Soames & Southam?

1. Translucent Zone, 2. Dark Zone, 3. Body of Lesion, 4. Surface Zone.

What characterizes the Translucent Zone in enamel caries?

It is the deepest part of the lesion with 1-2% mineral loss, often containing magnesium and carbonate.

What is the significance of the Dark Zone in carious lesions?

It lies adjacent to the translucent zone, has 2-4% mineral loss, and represents partial remineralization attempts.

What is the Body of Lesion in dental caries?

The central and most demineralized part of the lesion with the greatest mineral loss and increased porosity.

How does frequent sugar intake affect the oral environment?

It leads to fermentation and lactic acid production, creating an acidic environment that favors cariogenic bacteria.

What is the impact of saliva on the cariogenic biofilm?

Saliva buffering is less effective within a cariogenic biofilm, contributing to the persistence of acidic conditions.

What happens during the remineralization process with fluoride?

Fluoride helps form fluorapatite, which has a lower critical pH of around 4.5.

What is the role of calcium and phosphate in tooth remineralization?

They enhance the remineralization process when saliva is supersaturated with these minerals.

What is the surface zone in enamel caries?

A relatively intact outer enamel layer with pore volume

What characterizes the typical zoned structure of an early white spot lesion?

It includes a subsurface translucent zone covered by a surface zone, with potential cavitation and reactive changes in dentine.

What shape do smooth surface caries typically have?

Triangular or V-shaped, with the apex toward the dentinoenamel junction (DEJ) and the base at the tooth surface.

What is the path of smooth surface caries in enamel?

It follows enamel rods inward from the smooth surface.

What shape do pit and fissure caries typically have?

Triangular or cone-shaped (inverted-V), with the apex toward the occlusal surface.

What is the composition of dentine?

Approximately 70% inorganic hydroxyapatite, 20% organic material (primarily type I collagen), and 10% water.

What are the two main processes characterizing carious destruction in dentine?

Demineralization and proteolysis.

How does dentine respond to caries attack?

Dentine is a living tissue that can undergo defense reactions such as sclerosis, reactionary dentine formation, and sealing of dead tracts.

What occurs during the dentine caries process?

Bacteria extend down and multiply within the dentinal tubules, leading to demineralization and proteolytic activity.

What are the zones of dentine caries?

1. Zone of destruction, 2. Zone of bacterial invasion, 3. Zone of demineralization, 4. Translucent zone, 5. Reactionary dentine.

What features characterize the zone of destruction in dentine caries?

Complete breakdown of dentin, destroyed collagen matrix, and heavy bacterial infiltration.

What happens in the zone of bacterial invasion?

Bacteria invade and multiply within dentinal tubules, creating liquefaction foci and transverse clefts.

What is the zone of demineralization in dentine caries?

Intertubular dentin is demineralized while the collagen framework remains intact and bacteria are absent.

What defines the zone of translucent dentin?

Tubules are occluded with mineral deposits, appearing translucent in transmitted light, representing a defense mechanism.

What is reactionary dentine?

Dentine formed by existing odontoblasts in response to mild stimuli, protecting the pulp beneath the lesion.

What is reparative dentine?

Dentine formed by new odontoblast-like cells in response to severe injury, quickly protecting the pulp.

What is root caries?

Caries that starts directly in cementum or exposed root dentine, developing differently due to softer and less mineralized structure.

What are the two types of tertiary dentine?

Reactionary dentine and reparative dentine.