Dental Caries Quiz

Understanding Dental Caries: Causes, Pathogenesis, and Histological Effects

• Dental caries is a multifactorial, transmissible, infectious oral disease caused by the interaction of cariogenic oral flora with fermentable carbohydrate on the tooth over time.
• Dental plaque, a thin film of bacterial species, food remnants, and epithelial cells, is an etiological factor, not a cause of dental caries, and acts in the presence of pathologic bacteria.
• Pathogenic bacteria are microorganisms that ferment carbohydrates and produce acids that demineralize tooth structure.
• The pathogenesis of dental caries involves the adsorption of an organic film called "acquired pellicle" to the tooth surface, followed by the invasion of specific highly adherent bacteria, which produce lactic acid and decrease the pH of the biofilm.
• When the pH drops below critical levels, the tooth demineralizes to buffer the acid by losing Ca++ and Ph+++ ions, leading to the destruction and dissolution of dental hard tissue.
• Dental caries varies according to diet, hygiene, time of exposure, and affects signs and symptoms.
• The pH threshold for caries to occur is 5.5, and the bacteria most associated with caries include Actinomyces, Streptococcus mutans, and Lactobacillus.
• Histologically, dental caries affects both enamel and dentin, with enamel showing four main zones after sound enamel: normal, lesion, translucent, and dark zone.
• The clinical application of the dark zone is important as it does not permit light, and transillumination can be used to detect caries.
• Dentin caries has four zones: normal, sub-transparent, transparent, and turbid zones, with the superficial "infected" zone characterized by complete decomposition of the dentin and significant bacterial infiltration.
• Infected dentin is invaded by bacteria and has a denatured collagen network, while affected dentin is demineralized but not invaded by bacteria and can be preserved.
• Early enamel lesions appear as white spots and may appear darkened after remineralization, while nurse bottle caries can occur in infants with prolonged exposure to fermentable carbohydrates.