Oral Bacteria: The Hidden Threat

The mouth is home to millions of bacteria, both beneficial and harmful. When harmful oral bacteria grow unchecked, they can produce toxins that pose risks not only to oral health but also to systemic health.

These bacteria can lead to tooth decay, gum disease (gingivitis, periodontitis), and oral infections. They produce acids and toxins that damage tissues, cause inflammation, and destroy the bone and gums around teeth, potentially leading to tooth loss.

Additionally, some oral bacteria can enter the bloodstream, contributing to systemic health issues such as cardiovascular disease, diabetes, respiratory infections, preterm birth and low birth weight. Poor oral hygiene increases the risk of these hazards, emphasizing the importance of regular dental care.

Streptococcus Mutans

Streptococcus mutans is a gram-positive, facultative anaerobic bacterium commonly found in the human oral cavity. It plays a significant role in the development of dental caries (tooth decay) due to its ability to metabolize sugars into acids and form biofilms on teeth.

Streptococcus mutans resides in dental plaque and adheres to the tooth surface. It thrives in acidic environments, which it creates as a byproduct of sugar metabolism. It is a primary causative agent of dental cavities. Its ability to form biofilms and produce acids makes it a key contributor to enamel demineralization.

Streptococcus mutans produces extracellular polysaccharides, which enhance its adhesion and biofilm formation. It can adapt to fluctuating pH levels, enabling survival in acidic environments.

Streptococcus mutans metabolizes dietary sugars (sucrose, glucose, fructose) through glycolysis, producing lactic acid as a byproduct. Lactic acid lowers the pH in the oral cavity, leading to enamel demineralization and cavity formation.

Streptococcus mutans synthesize extracellular polysaccharides (EPS) from sucrose by glucosyltransferases and fructosyltransferases. They form a sticky matrix in dental plaque, facilitating bacterial adhesion and creating an environment for acid retention.

Dextran is a type of EPS that S. mutans produces from sucrose. Dextran strengthens biofilm structure, enhancing bacterial colonization and protection against saliva flow and antimicrobial agents.

Bacteriocins are antimicrobial peptides produced by S. mutans to outcompete other oral bacteria. They help mutans dominate the microbial community, allowing it to proliferate.

Hydrogen peroxide (H₂O₂) is produced under specific conditions. It is toxic to competing bacteria, enhancing S. mutans' survival in biofilms.

Porphyromonas Gingivalis

Porphyromonas gingivalis is a gram-negative, anaerobic bacterium strongly linked to chronic periodontitis (gum disease). It is a keystone pathogen that disrupts the balance of the oral microbiome, leading to inflammation and destruction of gum tissue and bone. It causes periodontitis, tooth loss, and gum recession. It contributes to cardiovascular disease, diabetes, Alzheimer's, and adverse pregnancy outcomes.

Gingipains are proteolytic enzymes produced by Porphyromonas gingivalis that play a major role in its virulence. These enzymes cause tissue destruction, break down host proteins like collagen, aiding in gum and bone damage, degrade immune components (cytokines, antibodies) to impair the host defense system, and liberate peptides and heme for bacterial growth.

Gingipains contribute to periodontitis, systemic inflammation, and diseases like Alzheimer's and cardiovascular conditions.

Fusobacterium Nucleatum

Fusobacterium nucleatum is a gram-negative, anaerobic bacterium commonly found in the human oral cavity. It plays a significant role in oral and systemic health due to its pathogenic potential. It contributes to periodontal diseases by promoting inflammation and tissue destruction. It is linked to colorectal cancer, adverse pregnancy outcomes (e.g., preterm birth), and cardiovascular disease.

Adhesins in Fusobacterium nucleatum are surface proteins that allow the bacterium to adhere to host cells and other microbes. They bind to host cell receptors, aiding in tissue invasion, facilitate coaggregation with other bacteria and immune evasion. They are essential for biofilm formation, colonization, and promoting diseases like periodontitis and colorectal cancer.

Fusobacterium nucleatum produces butyric acid, a short-chain fatty acid that contributes to tissue inflammation and destruction. This compound can damage host cells, suppress immune responses, and create an environment conducive to bacterial persistence, particularly in periodontal disease and systemic infections.

Treponema Denticola

Treponema denticola is a spirochete bacterium commonly found in the oral cavity, particularly in individuals with periodontal disease. It is a key pathogen in the progression of periodontitis, where it invades gum tissues, causing inflammation and tissue destruction.

Treponema denticola produces dentilisin, an enzyme that breaks down tissue proteins, which aids in its spread and exacerbates the severity of gum disease. Its presence is often associated with severe forms of gum infections and can contribute to tooth loss if not treated.

Actinobacillus Actinomycetemcomitans

Actinobacillus actinomycetemcomitans is a bacterium primarily associated with aggressive periodontitis, a severe form of gum disease. It produces leukotoxins that target and kill white blood cells, particularly neutrophils, impairing the body's immune response. This leads to chronic inflammation, tissue destruction, and potential tooth loss. A. actinomycetemcomitans is also linked to other systemic infections, especially in immunocompromised individuals.

Enterococcus Faecalis

Enterococcus faecalis is a bacterium commonly found in the gastrointestinal tract but can also be present in the mouth, especially in dental infections. It is often associated with root canal infections and dental abscesses, where it can survive in difficult-to-reach areas of the tooth.

While typically harmless, E. faecalis can become pathogenic under certain conditions, particularly in immunocompromised individuals. It is also linked to healthcare-associated infections like urinary tract infections, endocarditis, and sepsis. Its ability to form biofilms makes it resistant to antibiotics, complicating treatment.

Lactic Acid

Lactic acid is produced in the mouth by bacteria, especially Streptococcus mutans, when they metabolize sugars from food. While lactic acid itself isn’t directly harmful, it contributes to oral hazards when it lowers the pH in the mouth.

Lactic acid contributes to the demineralization of tooth enamel, weakening it and leading to cavities. When the acid breaks down the enamel, the tooth becomes more susceptible to decay.

Prolonged exposure to lactic acid, especially from sugary foods and beverages, can cause enamel erosion. Enamel wears down over time, leading to sensitive teeth and increasing the risk of cavities.

Acidic conditions in the mouth can irritate and inflame the gums, contributing to gum disease like gingivitis and periodontitis.

Lactic acid helps bacteria stick to tooth surfaces, forming plaque.

Plaque

Plaque is a sticky, colorless film of bacteria that forms on teeth, especially after eating. Plaque is a breeding ground for more harmful bacteria that can lead to further dental issues. If not removed through regular brushing and flossing, plaque can lead to several oral hazards.

Plaque irritates the gums, leading to inflammation (gingivitis). If untreated, it can progress to periodontitis, causing gum recession, bone loss, and tooth loss. Plaque buildup can contribute to persistent bad breath (halitosis) due to the bacteria in the plaque.

If plaque is not removed, it hardens into tartar (calculus), which can only be removed by a dentist and may lead to more serious oral health issues.

Prevention Tips

Brush your teeth at least twice a day with fluoride toothpaste to remove food particles and plaque, which harbor bacteria.

Floss daily to remove debris and plaque from between your teeth and along the gumline, areas your toothbrush might miss.

An antimicrobial mouthwash can help reduce bacteria and freshen breath. Look for one with fluoride or antibacterial properties.

Regular dental check-ups and cleanings (every six months) help identify and prevent bacterial infections before they become serious.

Avoid sugary foods and drinks, which promote the growth of harmful bacteria. Consume foods rich in fiber, vitamins, and minerals to support oral health.

Drinking water helps wash away food particles and bacteria in your mouth.

Avoid Smoking. Smoking weakens the immune system and promotes bacterial growth, leading to gum disease and other oral issues.

Use a tongue scraper. The tongue can harbor bacteria. Regularly scraping it can help reduce bacteria levels in the mouth.

Manage dry mouth. A dry mouth can allow bacteria to grow. Use saliva substitutes or drink water regularly to keep your mouth moist.

Consider probiotics as certain probiotics can help balance oral bacteria and reduce harmful strains.