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Odontogenic Infections

Q: What pathogenicity factors contribute to the cariogenicity of Streptococcus mutans?

The cariogenicity of Streptococcus mutans is tied to its role in the carious process, dental plaque formation, and acid production. Primary caries pathogen: S. mutans is a leading cause of dental caries.Acidogenesis: Streptococci ferment carbohydrates to produce organic acids, predominantly lactic acid, which demineralizes the hard dental tissues.Dental plaque participation: The pathogenesis centers on plaque formation and maturation, involving microbial adhesion to the pellicle, extracellular matrix production, and active bacterial replication.

Infectiones odontogenae

For medical students2 min readUpdated 2026-10-10

Odontogenic infections are a group of maxillofacial conditions triggered by primary pathology of the hard dental tissues. Their development is driven by the disruption of oral microbial biofilm homeostasis and the subsequent spread of microorganisms into deep surrounding tissues.

Primary CauseOral dysbiosis and microbial imbalance within natural biofilms.

Initiating TriggerDental caries acts as the starting trigger for deep inflammatory changes.

Flora CharacteristicsInfections are predominantly polymicrobial (involving consortia of 3 or more bacterial species).

Pathogenetic Mechanisms and Risk Factors

The pathogenesis relies on dysbiosis—a disruption of the delicate homeostasis within oral biofilms. Shifts in microbial equilibrium are triggered by various environmental factors, primarily dietary habits and antibiotic therapy that suppress normal microflora.

Additionally, systemic hormonal changes and hyposalivation (reduced salivary flow) play crucial roles. Hyposalivation may result from medication side effects or radiation therapy to the maxillofacial region.

Non-Inflammatory Lesions: Dental Caries

Dental caries is a classic example of a non-inflammatory odontogenic infection affecting exclusively the hard dental tissues. It serves as the primary catalyst for the entire subsequent cascade of purulent-inflammatory conditions.

The leading causative agents are various streptococcal species, specifically Streptococcus mutans, S. sanguis, S. oralis, S. gordonii, and S. mitis (biovar 1). They are accompanied by microbial associates including Veillonella species, actinomycetes, and lactobacilli.

Inflammatory Infections of the Tooth and Periodontium

These infections are classified by depth of microbial invasion and the specific tissues involved. Their hallmark feature is polymicrobiality. The microbial composition is highly dynamic, shifting according to the stage of disease, patient immune status, age, and prior pharmacotherapy.

Pulpitis (inflammation of the dental pulp). In the serous stage, streptococci, lactobacilli, and bacteroides predominate in the lesion. When the process transitions to a purulent form, hemolytic streptococci and Staphylococcus aureus come to the forefront.
Periodontitis (inflammation of the supporting structures of the teeth). In adult patients, Gram-negative rods dominate. These include obligate anaerobes (Porphyromonas gingivalis, Tannerella forsythia, Prevotella melaninogenica), facultative anaerobes (Aggregatibacter actinomycetemcomitans), and spirochetes (Treponema denticola). In adolescents, the microbiological profile differs: Aggregatibacter actinomycetemcomitans and Capnocytophaga species are isolated more frequently.

Purulent-Inflammatory Processes of the Jaws and Soft Tissues

Periostitis and Osteomyelitis. When the periosteum and bone tissue are involved, Staphylococcus aureus dominates in 30–50% of cases. Streptococci and anaerobic flora, including Peptococcus niger, Peptostreptococcus spp., and Bacteroides spp., are also active. If osteomyelitis is of traumatic origin, enterobacteria and Pseudomonas aeruginosa join the standard spectrum.
Abscesses and Cellulitis (Phlegmon). Anaerobes (Bacteroides, Peptostreptococcus) overwhelmingly dominate facial and neck soft tissue infections. Microbial associations involving Fusobacterium nucleatum and actinomycetes are common. In children, the flora differs: staphylococci and streptococci prevail, while in buccal cellulitis, Haemophilus influenzae type b and Streptococcus pneumoniae are frequently identified.

Spread of Infection and Generalization

When infection breaks beyond the primary focus (tooth or jaw), severe complications develop in adjacent spaces or the systemic circulation.

Maxillary Sinusitis. Characterized by mixed etiology, combining anaerobes (Bacteroides spp., Peptostreptococcus spp.) with typical respiratory pathogens (Haemophilus influenzae, S. pneumoniae). S. pyogenes or S. intermedius are identified less frequently.
Lymphadenitis and Adenophlegmon. Up to 80% of cases are caused by group A β-hemolytic streptococci and S. aureus. The anaerobic component includes specific species such as Propionibacterium acnes.
Generalization. When pathogens enter the bloodstream, systemic complications develop: sepsis, infective endocarditis (with valve involvement), mediastinitis, meningitis, and brain abscesses. Causative agents include anaerobes, streptococci, and staphylococci (including S. epidermidis).

Non-Odontogenic and Specific Infections

Maxillofacial inflammations of alternative genesis that are not directly linked to dental pathology include:

Stomatitis. Can be of fungal etiology (Candida albicans), viral (herpesviruses), or bacterial (corynebacteria, hemophilic bacteria, actinomycetes). Deep stomatitis is notably characterized by the predominance of anaerobic flora.
Parotitis. Major salivary gland infections are most commonly viral (mumps, influenza, parainfluenza, Coxsackie viruses), but bacterial etiologies involving oral residents, S. aureus, and Eikenella corrodens also occur.
Specific Infections. Classical systemic bacterial infections (tuberculosis, syphilis, diphtheria, gonococcal infection) and viral lesions (HIV infection, foot-and-mouth disease, vesicular stomatitis) may manifest within the oral cavity.

Frequently asked questions

What microorganisms comprise the normal (resident) oral microflora?

The resident oral microflora includes diverse bacteria, fungi, and protozoa, with anaerobes predominating.

Streptococci (Streptococcus salivarius, S. sanguis, S. mutans, S. milleri, S. mitis) account for about 50% of all residents.
Obligate anaerobes (Veillonella, peptostreptococci, lactobacilli, bacteroides, prevotella, porphyromonas, fusobacteria) predominate in specific niches (sublingual space, crypts).
Other bacteria: bifidobacteria, eubacteria, actinomycetes, hemophilic bacteria, leptotrichia, neisseria, staphylococci, peptococci, spirochetes.
Fungi: Candida species.
Protozoa: Entamoeba gingivalis, Trichomonas tenax.

What pathogenicity factors contribute to the cariogenicity of Streptococcus mutans?

The cariogenicity of Streptococcus mutans is tied to its role in the carious process, dental plaque formation, and acid production.

Primary caries pathogen: S. mutans is a leading cause of dental caries.
Acidogenesis: Streptococci ferment carbohydrates to produce organic acids, predominantly lactic acid, which demineralizes the hard dental tissues.
Dental plaque participation: The pathogenesis centers on plaque formation and maturation, involving microbial adhesion to the pellicle, extracellular matrix production, and active bacterial replication.

What are the stages of oral microbial biofilm (dental plaque) formation?

Biofilm formation progresses through several sequential stages:

Initial phase: Formation of the acquired pellicle on the tooth surface.
Adhesion and early colonization: Attachment of primary colonizers (aerobes and facultative anaerobes) to the pellicle, production of extracellular polysaccharides, and matrix formation.
Active reproduction and microbial succession: Rapid biomass increase and creation of anaerobic microenvironments by primary colonizers.
Late colonization (coaggregation): Attachment of secondary colonizers (strict anaerobes and spirochetes) to the established matrix along with the accumulation of their metabolic waste products.

How does the microflora of periodontitis differ between adults and adolescents?

Adult lesions are dominated by Gram-negative rods (obligate anaerobes like Porphyromonas gingivalis, spirochetes), whereas adolescents more frequently yield Aggregatibacter actinomycetemcomitans and Capnocytophaga species.

Which bacteria dominate in facial abscesses and cellulitis?

Purulent soft tissue infections are primarily driven by anaerobes—bacteroides and peptostreptococci. They frequently form consortia with Fusobacterium nucleatum and actinomycetes.

How does the flora shift when serous pulpitis transitions to purulent pulpitis?

During the serous inflammatory stage, streptococci, lactobacilli, and bacteroides predominate within the pulp. As the condition progresses to the purulent stage, hemolytic streptococci and Staphylococcus aureus become dominant.

Go deeper

Pathogenesis of microbial biofilms and mechanisms of oral dysbiosis.
Features of traumatic osteomyelitis: why Pseudomonas aeruginosa joins the infection.
Viral lesions of the oral mucosa: herpetic infections, foot-and-mouth disease, HIV manifestations.
Clinical presentations and microbiological diagnosis of maxillofacial actinomycosis.
The role of Candida species in deep stomatitis and hematogenous osteomyelitis.