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Questions and Answers
What is the primary characteristic that defines dental caries?
Which type of caries occurs specifically on the root surface of a tooth?
What is a contributing factor to dental caries related to tooth structure?
Which of the following bacteria are known to be acidogenic and contribute to dental caries?
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What is the cariostatic effect of fluoride primarily responsible for?
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What is one of the primary roles of the plaque matrix in relation to caries?
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Which factor is NOT considered to affect plaque formation?
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Which phase of enamel caries involves advanced demineralization and contains the largest area of the carious lesion?
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What is a characteristic feature of the surface zone in enamel caries?
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Which theory of dental caries is the most widely accepted?
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Study Notes
Dental Caries
- A disease that causes demineralization of the inorganic part of the tooth, followed by dissolution of the organic part by bacteria.
- Most common dental disease worldwide.
Classification
- Pits & Fissures Caries: Occurs in grooves and pits of the tooth surface.
- Smooth Surface Caries: Occurs on smooth surfaces of the tooth.
- Cemental (Root) Caries: Occurs on the root surface of the tooth exposed due to gum recession.
- Recurrent Caries: Occurs around a pre-existing restoration.
- Acute (Rampant) Caries: Rapidly progressing caries affecting multiple teeth.
- Arrested Caries: Caries that has stopped progressing.
Contributing Factors
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Susceptible Tooth Surface:
- Tooth Position: Teeth that are crowded or misaligned are more susceptible.
- Tooth Morphology: Teeth with deep pits and fissures are more susceptible.
- Tooth Structure: Teeth with thin enamel are more prone to caries.
- Genetic Factors: Some individuals are genetically predisposed to caries.
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Fluoride: Fluoride strengthens tooth enamel, making it less susceptible to caries.
- Reduces enamel solubility by converting hydroxyapatite to fluoroapatite crystals.
- Enhances remineralization of carious lesions.
- Exhibits antibacterial activity by reducing lactic acid production, glucose uptake, and bacterial adhesion.
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Carbohydrates:
- Type: Monosaccharides, disaccharides, and polysaccharides contribute to caries formation.
- Amount: Higher intake of carbohydrates increases caries risk.
- Frequency: Frequent consumption of carbohydrates increases caries risk.
- Consistency: Sticky carbohydrates adhere to teeth for longer, increasing caries risk.
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Microorganisms:
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Acidogenic bacteria:
- Lactobacilli and Streptococci (Streptococcus mutans) produce acids that demineralize enamel.
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Proteolytic bacteria:
- Actinomyces, Clostridia, and Pseudomonas degrade the organic matrix of the tooth.
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Chromogenic bacteria:
- Aspergillis bacteria contribute to tooth discoloration.
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Acidogenic bacteria:
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Essential Features of Cariogenic Bacteria:
- Acidogenic
- Produce low pH (lower than 5.5)
- Aciduric (resistant to acidic conditions)
- Possess attachment mechanisms for adhesion to tooth surfaces
- Produce abundant polysaccharides for plaque matrix formation
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Dental Plaque:
- Adherent bacterial structure formed on tooth surfaces.
- Contains a large number of microorganisms surrounded by extracellular material.
- Two major interfaces:
- Internal (pellicle): Adheres to the tooth surface.
- External (plaque saliva interface): Exposed to saliva.
- Types:
- Subgingival: Found below the gum line.
- Supragingival: Found above the gum line.
- Composition:
- Microorganisms
- Matrix: Protein, lipids, carbohydrates, inorganic components, and water.
- Role of plaque matrix:
- Acts as a diffusion limiting membrane, retaining acids in high concentrations to initiate caries.
- Slows down the entry of buffers from saliva, delaying neutralization.
- Factors affecting plaque formation:
- Anatomy and position of teeth
- Presence of appliances
- Tooth surface structure
- Friction from diet
- Oral hygiene procedures
- Diet composition
- Mechanism of action:
- Allows bacteria and acids to adhere to tooth surfaces.
- Prevents escape of acids and entry of salivary buffers.
Saliva & Caries
- Role of saliva in caries:
- Washing effect: Removes food debris and bacteria.
- Buffering effect: Phosphate and bicarbonate content neutralize acids.
- Salivary antibodies (IgA): Fight against bacteria.
- Antibacterial substances: Lysozymes, peroxidases, and lactoferrin inhibit bacterial growth.
Theories of Dental Caries
- Acidogenic theory (Miller's chemico-parasitic theory): Most accepted theory.
- Proteolytic theory: Explains penetrating caries under restorations and caries of impacted teeth.
- Proteolosis-chelation theory: Not as widely accepted.
Pathology of Enamel Caries
Clinical Picture
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Initial stage: White chalky area.
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Progression: Rough to the probe with staining.
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Advanced stage: Cavitations occur.
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Lesion is cone-shaped:
- Pits & fissures caries: Base towards the dentoenamel junction (DEJ), apex towards the surface.
- Smooth surface caries: Base towards the surface, apex towards the DEJ.
Microscopic Picture
- Polarized light microscope reveals four phases of enamel caries:
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Initiation phase:
- Translucent zone: Initial demineralization, 1-2% pores.
- Dark zone: Further demineralization, 2-4% micropores.
- Body of the lesion: Advanced demineralization, 5% pores at periphery, 25% pores at center, translucent.
- Surface zone: Appears radio-opaque and harder than deeper zones due to continuous remineralization, fluoride, insoluble proteins, and prism-less enamel.
- Phase of bacterial invasion: Bacteria invade the enamel through the spaces created by acids.
- Phase of destruction: Proteolytic bacteria degrade the organic matrix of the enamel.
- Phase of secondary enamel caries: Acid and bacteria spread laterally along the DEJ, invading the enamel from beneath.
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Initiation phase:
Pathology of Dentin Caries
Clinical Picture
- Brownish and soft to the probe.
- Cone-shaped with the base towards the DEJ and the apex towards the pulp.
Microscopic Picture
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Initial Uninfected Lesions: Occurs before enamel cavitations.
- Zone 1: Reactionary or reparative dentin formation (secondary dentin).
- Zone 2: Sclerotic or translucent dentin formation (calcium ion deposition).
- Zone 3: Body of the lesion (dead tract).
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Infected Lesion: Occurs after enamel cavitations, bacteria invade dentin through dentinal tubules:
- First wave: Acidogenic bacteria decalcify dentin, leaving organic matrix intact.
- Second wave: Mixed infection containing proteolytic bacteria distort the organic matrix.
- Zone 1: Mild pulp inflammation.
- Zone 2: Reparative or reactionary dentin.
- Zone 3: Sclerotic dentin.
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Zone 4: Body of the lesion:
- Decalcified uninfected zone
- Decalcified infected zone
- Destruction zone
- Beading: Lateral distension of dentinal tubules by bacteria.
- Liquefaction foci: Coalescence of neighboring beads, located along the long axis of dentinal tubules.
- Transverse clefts: Liquefaction foci located at right angles to the dentinal tubules due to lateral branches.
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Description
Explore the intricate details of dental caries, a common disease that leads to tooth demineralization. This quiz contains information on various types of caries and the factors contributing to their development. Enhance your understanding of this dental health issue and its classifications.
