تعريف تسوس الأسنان

Dental Caries: Definition

• Dental caries is a microbiological disease of teeth's hard structures.
• It leads to localized demineralization of the inorganic portion and destruction of the organic substances of the tooth.

Sites of Dental Caries

• Pits and fissures on occlusal surfaces of molars and premolars.
• Buccal pits of molars.
• Palatal pits of maxillary incisors.
• Enamel of the cervical margin of the tooth just coronal to the gingival margin.
• Proximal enamel smooth surfaces apical to the contact point.
• Teeth with gingival recession due to periodontal disease.
• Margins of restorations (deficient or overhanging).
• Tooth surfaces adjacent to dentures and bridges.

Etiology of Dental Caries

• Diet: Reduce intake of cariogenic sugars (especially sucrose).
• Bacteria: Reduce Streptococcus mutans numbers by reducing sugar intake or active/passive immunization.
• Time: Avoid frequent sucrose intake (snacking). Stimulate salivary flow and sugar clearance.
• Susceptible Surface (Host): Water fluoridation and prevention during post-eruptive maturation. Fissure sealing and properly contoured restorations.

Etiology of Dental Caries (Mechanism)

• Plaque (with acidogenic bacteria) + Enzymes + Food → Acids → Tooth → Carious Lesions

Theories of Dental Caries

• Acidogenic Theory (1890, WD Miller): Demineralization of enamel, followed by dissolution of softened enamel and dentin.
• Proteolytic theory: Proteolysis of the organic components of the tooth. - Proteolysis-chelation theory: Simultaneous proteolysis and chelation. Oral bacteria attack organic components of enamel (proteolysis), breakdown products have chelating properties which dissolves tooth minerals.

Factors that Cause Decay

• Role of carbohydrates (frequency, composition, form, time of contact, presence of other food components).
• Role of microorganisms (acid-production).
• Role of acids (pH 5.5 is critical).
• Role of dental plaque (environment for bacteria to form acid, leading to demineralization).

Role of Microorganisms

• S. mutans is important for the initiation (and maybe progression) of caries. Other important species include S. milleri, S. mitior, S. sanguis, and S. salivaris and Lactobacilli (e.g., L. acidophillus, and L. casei).
• Acid production from the action of microorganisms on carbohydrates.

Role of Acids

• Play a crucial role in the pathogenesis of dental caries.
• pH 5.5 is the critical pH below which tooth substance demineralization begins.
• Demineralization appears as tenacious, thin films that accumulate within 24-48 hours on uncleaned tooth surfaces.

Role of Dental Plaque

• Also known as microbial plaque, essential for the initiation of caries.
• Provides an environment for bacteria to form acid, causing demineralization of hard tooth tissues.

Progression of Dental Caries

• Normal tooth → White chalky spot → Incipient lesion → Cavitation → Involvement of dentin and pulp → Pulp inflammation → Pulp necrosis → Periradicular lesion

Local Factors Affecting the Incidence of Caries (Host)

• Tooth: Morphology, composition, position
• Substrate: Saliva (composition, quantity, pH, viscosity, antibacterial factors)

Local Factors Affecting the Incidence of Caries (Other factors)

• Diet\
  • Physical factors
  • Carbohydrate content (refined cariogenic carbohydrates on tooth surface, vitamin content, fluoride content, fat content).
• Microorganisms: Streptococcus mutans and Lactobacillus.
• Time period.

Classification of Dental Caries

• Nature of attack (primary, secondary)
• Progression of caries (acute, chronic)
• Surfaces involved (pit and fissure, smooth surface)
• Direction of attack (forward, backward)
• Number of surfaces involved (simple, compound, complex )
• GV Black Classification (Class I, II, III, IV, V, VI).
• Location of the lesion (pit and fissure, smooth surface, cervical, buccal, lingual or palatal and root).
• Tissues involved (enamel, dentin, cementum) (senile, residual).

Clinical Features of Caries

• Various types of Caries (Interproximal, Cervical, Buccal, Lingual, Palatal, Pit and fissure, Root) and their characteristics. Clinical features are described in detail for each type of caries.

Zones in Enamel Caries

• Zone 1: Translucent zone
• Zone 2: Dark zone
• Zone 3: Body of the lesion
• Zone 4: Surface zone

Zones of Dentinal Caries

• Zone 1: Normal dentin
• Zone 2: Zone of dentinal sclerosis
• Zone 3: Zone of decalcification of dentin(
• Zone 4: Zone of bacterial invasion
• Zone 5: Zone of decomposed dentin.

Special Types of Caries

• Nursing Bottle Caries: Etiology, pathogenesis, clinical features, prevention.
• Rampant Caries: Etiology, clinical features.
• Arrested Caries: Clinical features.

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