Etiology (etiological triad)
Although the exact cause of caries development is not fully understood, a combination of three obligatory factors is considered paramount:
- Cariogenic diet: excessive carbohydrate intake (especially sucrose).
- Individual predisposition of the patient's body.
- Oral microflora: active bacterial activity.
The biochemical mechanism of tooth destruction is based on the interaction between microorganisms and food substrate. Excess sugar is fermented by bacteria to produce organic acids (lactic, butyric, acetic). An acid attack occurs, leading to enamel demineralization. Meanwhile, bacterial polysaccharides block natural remineralization processes, especially if the pH shifts toward the alkaline side. Additionally, microbial proteases degrade the organic matrix of the tooth (proteolysis).
Key causative agents
The pathogenesis of caries involves two main functional groups of bacteria:
- Acid-producing (acidogenic): streptococci play the primary role here, predominantly Streptococcus mutans. Lactobacilli also actively participate in this group.
- Proteolytic: represented by peptostreptococci, bacteroids, and other non-spore-forming anaerobes.
As the carious process deepens, the composition of the microbiota changes. Nearly all oral resident species become involved, while obligate anaerobes and enterococci dominate the deepest affected layers.
Stages of progression
The infection spreads from the tooth surface inward following a specific pattern.
Enamel involvement Poor hygiene often acts as the trigger. Dental plaque thickens, bacteria multiply within it, dissolving 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 because it contains fewer calcium salts, its main substance is poorly calcified (serving as an excellent nutrient medium), and dentinal tubules are present. Decalcification occurs, cracks appear, and they become filled with microbes and detritus.
Pulp and periodontal involvement Microbes invade the pulp, causing damage and atrophy of odontoblasts. Viridans streptococci (S. milleri), lactobacilli, and anaerobes are detected during the development of pulpitis. In cases of periodontitis, Aggregatibacter actinomycetemcomitans is considered a key pathogen, along with various periodontopathogenic species (e.g., Porphyromonas gingivalis).
Interestingly, root caries develops slowly: putrefactive processes begin in the necrotic pulp, shifting the pH toward the alkaline side, which slows down bacterial proliferation.
Prognosis and prevention
The number of lactobacilli is used as a marker of carious process activity. Their titer can be used to assess the severity of the pathology and predict its further course.
Preventive measures are divided into general and local:
- Dietary: a balanced diet with an adequate amount of proteins, fats, minerals (calcium, phosphorus), and vitamins (A, C, B1, D2).
- Physical: UV irradiation, which is particularly important for pregnant women to ensure the proper formation of the fetus's dentofacial system.
- Chemical: fluoridation (using fluoride-containing toothpastes and varnishes) is indicated when there is a deficiency of fluoride in water.
- Mechanical: regular removal of bacterial plaque using toothbrushes, flosses, and mouthwashes.
Promising developments of a caries vaccine are also currently underway. Its action will aim to produce antibodies that prevent bacteria from attaching to the enamel and forming dental plaque.
Briefly: answers to topical questions
What local oral immunity factors protect dental tissues from developing caries?
Protection of dental tissues against caries is provided by specific and nonspecific factors of local oral fluid immunity.
The main defense mechanisms include:
- Secretory immunoglobulin A (sIgA) — blocks the attachment (adhesion) of foreign microbes to the epithelium.
- Antimicrobial peptides — provide chemical protection of the oral cavity.
- Lysozyme — an enzyme that inhibits bacterial adhesion.
Buffer properties and the remineralizing potential of saliva also play an important role, while the mechanical flushing action of saliva and tongue movements promote natural oral self-cleaning.
Using which enzymes do cariogenic bacteria synthesize insoluble polysaccharides (dextran, levan) from sucrose?
According to sources, dextrans and levans are formed under the action of extracellular bacterial enzymes on environmental disaccharides, specifically sucrose. The specific names of these enzymes are not stated in the cited sources. The resulting exopolysaccharides facilitate bacterial attachment to teeth and dental plaque formation.
Specifically which bacterial enzymes perform proteolysis of the organic tooth matrix in caries?
Proteolysis of the organic tooth matrix in caries is carried out by microbial proteases. The cited sources do not specify the exact names of these enzymes. Peptostreptococci, bacteroids, and other non-spore-forming anaerobes belong to the proteolytic group of oral microflora.
Class and exam questions
Which bacteria trigger enamel demineralization?
The main causative agent is the acid-producing microbe Streptococcus mutans. It ferments sucrose into organic acids, which dissolve enamel.
Why does caries develop faster in dentin than in enamel?
Dentin contains fewer calcium salts, is permeated by dentinal tubules, and its poorly calcified ground substance serves as a good nutrient medium for microbes.
Which group of microorganisms predominates in deep carious cavities?
Obligate anaerobes and enterococci predominate in the deepest layers of affected tissues.
How can the activity of the carious process be assessed in the laboratory?
The count of lactobacilli (Lactobacillus) in the oral cavity serves as an indicator. Their high titer indicates an active disease course.
What else to study on this topic
- Mechanisms of Streptococcus mutans adhesion to tooth enamel
- The role of Aggregatibacter actinomycetemcomitans in periodontitis development
- Biochemical pathways of sucrose fermentation by oral bacteria
- Prospects for vaccine development and mechanisms of action against caries
- Interaction of proteolytic bacteria with the organic tooth matrix
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