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HomeHealth articlesperiodontal gum diseaseWhat Is the Pathogenesis of Periodontal Disease?

Microbial Pathogenesis of Periodontal Disease

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Periodontal disease is a serious infection of gums and tooth-supporting structures, caused by bacterial invasion. Read the article to know more.

Medically reviewed by

Dr. Sowmiya D

Published At July 13, 2022
Reviewed AtAugust 14, 2023


The tooth is placed in the bony socket and supported by gums. Periodontium refers to the unit consisting of cementum, periodontal ligament, alveolar bone, and gingival tissue. It surrounds and supports the tooth and helps in the proper functioning of the teeth. Periodontal disease is caused by the infection of the gums and bone that supports the tooth. The initial stage is called gingivitis or inflammation of the gingiva. Gingivitis if not treated progresses to periodontitis.

How Is Periodontal Disease Linked to Microbial Infection?

Periodontal disease is a polymicrobial infection in the subgingival crevices of the teeth. Periodontal disease is not only a diverse clinical entity that induces an inflammation process, but in turn, it destroys the tooth attachment apparatus of the periodontal ligament fibers. Consequently, there is a loss of supporting alveolar bone. If left untreated, it is the most common disease process behind natural tooth loss. The increasing two-way relationship established over the recent decades through research is of periodontal disease linked to systemic diseases ranging from cardiovascular disease to complications in pregnancy like preterm birth and low birth weight infants. The causative in this systemic disease process is associated with specific virulence factors (molecules that assist bacterial colonization).

What Is Bacterial Biofilm Deposition?

The bacterial colonization is mainly due to plaque biofilm, the main reason for the disease process. The interactions between the bacteria and biofilm result in the expression or inhibition of specific virulence factors. Even though diversely as many as 500 different bacterial species are found in the oral cavity, the colonization by different microorganisms results in a biofilm composition that comprises gram-positive, gram-negative, aerobic, facultative, and anaerobic microorganisms.

The acquired pellicle is the biofilm that coats the outer surface of the complex and soft tissues of the tooth. It is free of bacteria and is composed of mucins, proteins, and glycoproteins. The deposition of bacteria and other microorganisms on the tooth surface begins with the adherence of pathogens such as streptococci and actinomycetes species. The pili and outer membrane proteins of the bacteria are responsible for the surface attachment of the bacteria to the tooth surface. As the biofilm later expands or develops on the tooth surface, varying high and low bacterial biomass concentrations of these organisms interact with saliva or water, providing a movement of essential nutrients responsible for the growth of the microorganisms and excretion of metabolic byproducts. Unfortunately, most research theories or hypotheses focus on the subgingival environment of the tooth that gets affected detrimentally by the expansion of the growing microbial complex. This leads to a sequel of epithelial apical migration and destruction of the periodontal attachment apparatus.

What Are Subgingival Microbial Organisms?

The primary subgingival microorganisms are consistently found to be P. gingivalis, which has adhering potential to a maximum extent. Research shows that P. gingivalis can interact with later bacterial colonizing flora like F. nucleatum, T. denticola, Treponema medium, B. forsythus, etc. These interactions not only promote P. gingivalis colonization as a plaque biofilm but eventually bind to epithelial cells, fibroblasts, or even red blood cells in the erythrocytes and other components constituting the extracellular matrix. These interactions are mediated by P. gingivalis, with its pathogenic action facilitated by enzymes breaking the proteins. The tooth-associated plaque is usually a mixture of microbial contamination that comprises gram-positive rods and cocci.

In contrast, the plaque associated with the epithelial tissues that line the gingival crevice is predominated by gram-negative rods and spirochetes bacterium. Also, there may be an increased prevalence of several bacterial origins that have been hypothesized as an essential aggravator in the development of periodontitis. This is studied histopathologically by the pathologist with the study of matured subgingival plaque. Various general constituents of bacterial biomass are Treponema, Porphyromonas, Prevotella, Peptostreptococcus, Fusobacterium, Actinobacillus, etc. In recent decades, specific techniques have been employed to determine the exact bacterial cluster responsible for the disease.

How Do Microorganisms Invade the Host Tissues?

The most important hallmark of pathogenesis is the ability of the microorganisms to cause the disease. When the bacterium invades the surrounding tissues, they cause the activation of the host immune response because of the continued bacterial survival or bacterial replication. According to research, this ability of the microorganisms to cause host immune response is found in these species, which include A. actinomycetemcomitans, P. gingivalis, P. intermedia, and F. nucleatum.

What Are the Management Approaches?

Though only good oral hygiene in itself is capable of reducing bacterial growth in shallow to moderately deep periodontal pockets, research shows the most effective treatment strategies to counteract periodontal diseases and infections are through scaling, root planing, and systemic or local antibiotic therapies that should be implemented along with rigorous oral hygiene. Systemic antimicrobial drugs or locally delivered antimicrobial agents can be administered by the dental surgeon directly into a periodontal pocket to observe improvement in clinical parameters like bleeding on probing, reduction in pocket depth, and clinical attachment levels. In addition, systemic antibiotic therapies may be combined with scaling and root planing by the dentist or the periodontist, especially in aggressive cases of periodontitis or periodontal groups of infections. In such cases, the deep periodontal pockets may be non-responsive to local drug delivery.

What Are the Different Ways to Reduce the Microbial Load in Periodontitis?

  • Regular brushing twice a day.

  • Flossing and use of mouthwashes.

  • Intake of prebiotics.

  • Drink enough water.

  • Reduce the intake of carbohydrates.

  • Increased intake of omega-3 fatty acids and reduction of omega-6 fatty acids.

  • Increased intake of vitamin C.

  • Eating fiber-rich food.


To conclude, it is not only proper oral hygiene but also education on the patient's periodontal health that is essential for long-term success in patients suffering from periodontal disease. There are numerous periodontal pathogens, and regular dental checkups, scaling, root planing, and antibiotic therapies are required to establish an equilibrium between the host tissue and pathogens.

Frequently Asked Questions


What type of pathogenesis is seen in periodontal disease?

Bacterial infection usually causes chronic periodontitis. However the major role in the pathogenesis and progression of chronic periodontitis is due to interaction between microbial environment, immunological conditions and genetic factors. Homeostatic immunity is maintained through periodontal health is also associated with symbiotic microbiota. Periodontitis is also associated with a dysbiotic polymicrobial community, in which different members have synergitic role in distinct mode promoting the destructive inflammation.


Name the main pathogens in periodontal disease?

The periodontal disease is caused by an periodontal pathogens mainly includes Aggrebacter actinomycetemcomitans, Fusobacterium nucleatum, Peptostreptococcus micors, porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, Treponema forsythia, Putative periodontal pathogens like Filifactor alocis, and Parvimonas microorganisms.


Name the bacterial pathogens present in the periodontal disease?

The bacterial presence results in acute and chronic inflammation, which can also result in the pathological disease. Few examples of high risk periodontal pathogens are Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema Denticola (Td), and Fusobacterium Nucleatum (Fn). these are more prevalent seen in periodontitis disease.


Why do bacteria cause periodontal diseases?

Bacterial  presence in the mouth results in periodontal disease. Bacteria present in the mouth has a capacity to infect the tissues surrounding the tooth resulting in periodontal disease.


What Is the Most Common Type of Pathogen Present in Chronic Periodontitis?

Usually many studies suggest that anaerobic bacteria is the most common type resulting in chronic periodontitis, along with it aerobic and microaerophilic organisms are also associated. Some of the examples of anaerobic pathogens like Fusobacterium spp, Bacteroides Fragilis, Porphyromonas spp, and Prevotella intermedia.


How Does Microbial Shift Occur From Periodontal Health to Disease?

Microbial shift is also called dysbiosis, referring to the concept of few diseases occurring due to a decrease in the number of beneficial symbionts and or an increase in the number of pathogens.


Name the Risk Factors Associated With Pathogenesis of Periodontal Disease?

The main risk factors for the pathogenesis of periodontitis will be smoking and type 1 and 2 diabetes. Whereas presence of some etiological microorganisms like P. gingivalis, T. forsythia and A. actinomycetemcomitanas are also defined as risk indicators. It is very important to talk to an individual about any potential risk factors faced by them. The periodontist should classify the disease and establish the right treatment plan. Given below are the few risk factors that causes periodontitis like:
 - Genetics.
 - Stress.
 - Age.
 - Smoking/tobacco usage.
 - Obesity or poor nutrition.
 - Clenching or grinding their teeth.
 - Other systemic diseases.
 - And using medications.


Which Is the Most Common Type of Periodontitis?

Chronic periodontitis is the most common and frequently seen periodontitis usually characterized by pocket formation and or recession of the gingiva. This disease is more prevalent in adults and also occurs in any age resulting in inflammation within the supporting tissues of the teeth and the subsequent bone loss also occurs.


Name the Pathogens, Which Are Present in the Aggressive Periodontitis?

Usually the generalized form of aggressive periodontitis is firmly associated with bacteria like Porphyromonas gingivalis, Agregatibacter actinomycetemcomitans and Tannerella forsythia. And few other microbial species are also associated with this disease as suggested by recent studies.


Are Pyorrhea and Periodontitis Defined as the Same?

Yes, pyorrhea is also called periodontitis. Periodontitis is a multifactorial disease affecting the oral gums and it is usually defined as an inflammation caused by a bacteria. This disease can also result in gingival recession, destruction of supporting bone of the tooth and also in the worst cases it results in the loss of the tooth.


What Type of Microbes Are Seen in Periodontal Infection?

Usually periodontitis infection is a mixed type involving anaerobes like Treponema denticola and Porphyromonas gingivitis. Localized juvenile periodontitis is a localized form that occurs due to the microaerophile Actinobacillus actinomycetemcomitans.


Which Type of Disease Is Linked to Periodontal Disease?

Gingivitis is a type of disease which is directly linked to periodontal disease. In the early stages of disease, gums becomes swollen and red and sometimes it may bleed resulting in gingivitis. And afterwards periodontal disease is caused due to infections and inflammation in the gums, bones surrounding and supporting the tooth.


Do Bacteria Cause Periodontal Diseases?

Yes, bacterial presence in the mouth results in periodontal disease. Bacteria present in the mouth has the capacity to infect the tissues surrounding the tooth resulting in periodontal disease. Localized juvenile periodontitis is a localized form that occurs due to the microaerophile Actinobacillus actinomycetemcomitans. Usually periodontitis infection is a mixed type involving anaerobes like Treponema denticola and Porphyromonas gingivitis.


What Are the Major Cause of Periodontal Disease?

Bacteria present in the mouth is the main cause of periodontal disease, because bacteria usually stays in the mouth infecting the tissues surrounding the tooth resulting in inflammation around the tooth leading to periodontal disease. On long duration, bacterial stay on teeth results in the formation of a film known as plaque, which gradually hardens resulting in the tartar also known as calculus.
Dr. Achanta Krishna Swaroop
Dr. Achanta Krishna Swaroop



periodontal gum diseaseporphyromonas gingivalis
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