Etiological Triad
Although the exact pathogenesis is multifactorial, dental caries development requires the combination of three core factors:
- Cariogenic Diet: Excess intake of carbohydrates (especially sucrose).
- Host Susceptibility: Individual patient predisposition.
- Oral Microbiota: Active bacterial metabolism.
The biochemical mechanism of tooth destruction relies on the interaction between microorganisms and dietary substrates. Excess sugars are fermented by bacteria, producing organic acids (lactic, butyric, acetic). This triggers an acid attack, leading to enamel demineralization. Concurrently, bacterial polysaccharides block natural remineralization processes, particularly when the pH shifts toward alkalinity. Additionally, microbial proteases degrade the organic matrix of the tooth (proteolysis).
Key Pathogens
The pathogenesis of caries involves two main functional groups of bacteria:
- Acidogenic (Acid-Producing): Dominated by streptococci, primarily Streptococcus mutans, alongside Lactobacillus species.
- Proteolytic: Represented by Peptostreptococcus, Bacteroides, and other non-spore-forming anaerobes.
As the carious process deepens, the composition of the microbiota shifts. Almost all oral resident flora become involved, with strict anaerobes and enterococci dominating the deepest affected layers.
Stages of Progression
The infection spreads from the tooth surface inward following a distinct pattern.
Enamel Involvement Poor oral hygiene often acts as the initiating factor. Dental plaque thickens, allowing bacteria to multiply and dissolve the pellicle (protective film). Microbes penetrate deeper through enamel lamellae, enzymatically dissolving the enamel and forming a cavity.
Dentin Involvement Destruction proceeds significantly faster in dentin. This is due to its lower calcium salt content, a poorly mineralized organic matrix that serves as an excellent nutrient medium, and the presence of dentinal tubules. Decalcification occurs, leading to cracks filled with microbes and detritus.
Pulp and Periodontal Involvement Microbes infiltrate the pulp, causing damage and atrophy of odontoblasts. Viridans group streptococci (S. milleri), lactobacilli, and anaerobes are frequently identified in pulpitis. In periodontitis, Aggregatibacter actinomycetemcomitans and various periodontal pathogens (e.g., Porphyromonas gingivalis) are key causative agents.
Root caries develops slowly: putrefactive processes begin in the necrotic pulp, shifting the pH to alkaline levels and slowing bacterial proliferation.
Prognosis and Prevention
The concentration of lactobacilli serves as a marker for caries activity. Their titer reflects the severity of the pathology and helps predict its further course.
Preventive measures are divided into general and local:
- Dietary: A balanced diet with adequate proteins, fats, minerals (calcium, phosphorus), and vitamins (A, C, B1, D2).
- Physical: UV irradiation, particularly important during pregnancy for the proper development of the fetal dental system.
- Chemical: Fluoridation (using fluoride-containing toothpastes and varnishes) indicated for areas with low water fluoridation.
- Mechanical: Regular removal of bacterial plaque using toothbrushes, dental floss, and mouthwashes.
Promising developments also include anti-caries vaccines. Their action aims to induce antibodies that prevent bacteria from adhering to the enamel and forming dental plaque.