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Does Periodontal Infection have a role in Pulmonary Disease?

There are several studies which show evidence that state that periodontitis may have a contributory role in the onset and progression of pulmonary diseases. Read to know more.

Periodontal Infection

Periodontitis: not just an oral health problem

Periodontitis is an infectious inflammatory disease caused by the bacteria of the dental plaque, resulting in the progressive destruction of the gums supporting the teeth and results in tooth loss. The chronic nature of periodontal inflammation, aetiology and pathogenesis, and the infection and inflammatory response can also have its effect elsewhere in the body.

Numerous researches in this field have led to understanding the link between periodontitis and systemic diseases. The most studied and linked diseases with periodontitis are Diabetes, cardiovascular disease , Pregnancy and respiratory disease1

Fig 1: Impact of periodontitis on the body

Fig 1: Impact of periodontitis on the body

Prevalence of respiratory diseases among patients with periodontal diseases

There are several studies which show evidence that state that periodontitis may have a contributory role in the onset and progression of pulmonary diseases.2

In a study assessing a total of 700 patients suffering from pulmonary diseases including tuberculosis (TB), chronic obstructive pulmonary disease, or pneumonia within the age group of 12–70 years the presence of periodontal diseases was assessed. Periodontal Disease Index and Periodontal Index for Risk of Infectiousness were recorded for all patients. 2

  • Patients with pulmonary diseases showed a statistically significant prevalence of the periodontal disease with higher values of periodontal disease index (31%) and periodontal index for risk of infectiousness (55%).2
  • Patients suffering from TB showed the highest prevalence of periodontitis with a greater number of males (43%) being affected as compared to females. 2

Various respiratory diseases that can be caused due to periodontal diseases

During periodontal infection, the microorganisms may enter the lung by inhalation, but the most common route of infection is the aspiration of oropharyngeal secretions. This can lead to several major respiratory diseases such as as3

  • Bacterial pneumonia
  • Chronic obstructive pulmonary disease (COPD) and
  • Emphysema

Dental plaque: a reservoir of pulmonary pathogens

During periodontal infection, there is a significant increase in the amount of plaque and biofilms that are formed. There are several hypothesis explaining the prime role of periodontal bacteria in the etiopathogenesis of pulmonary infections4

Aspiration of oral pathogens

The etiopathogenesis involved in adult bacterial pneumonia is through aspiration of oropharyngeal secretions loaded with pathogens into the lower respiratory tract.3,4

This leads to a collapse in the host immune system responsible for eliminating the aspirated oral pathogens, which then multiply and flourish, causing pulmonary infection. As pneumonia is majorly caused by anaerobic bacterial species, periodontitis patients carrying a large number of subgingival anaerobic bacteria can be at a higher risk. 3,4

Fig 2: Mechanism of pulmonary infection via aspiration route4

Fig 2: Mechanism of pulmonary infection via aspiration route4

Modification of mucosal surfaces by periodontal disease-associated enzymes in saliva

Saliva contains a wide assortment of hydrolytic enzymes, and the amount of enzyme activity in the saliva is related to the periodontal and oral hygiene status of the patient. In patients having periodontal disease and elevated levels of proteolytic bacteria such as P. gingivalis and spirochetes, protease activity may alter the mucosal epithelium to increase the adhesion and colonization of respiratory pathogens.

These bacteria may also produce other enzymes such as mannosidase, fucosidase, hexosaminidase, and sialidase. Exposure of epithelium and glycoproteins by such enzymes may increase the adhesion of Gram-negative bacteria to the mucosal surface.5                                                                           

Fig 3: Periodontal disease-associated enzymes in saliva and their role5

Fig 3: Periodontal disease-associated enzymes in saliva and their role5

Alterations in respiratory epithelium by cytokines

Oral bacteria in secretions interacts with the respiratory epithelial surfaces and may adhere to the mucosal surface. These bacteria may then stimulate cytokine production by mucosal epithelium. This may then contaminate the distal respiratory epithelium to stimulate the respiratory epithelial cells. These stimulated cells then release other cytokines that recruit inflammatory cells. These inflammatory cells then release hydrolytic enzymes and other modifying molecules, resulting in the damaged epithelium that may be more susceptible to colonization by respiratory pathogens.3,4

Fig 5: Bacterial involvement in alteration of respiratory epithelium

Fig 5: Bacterial involvement in alteration of respiratory epithelium

Early intervention and its effect on treatment outcome

There are several studies which show the importance of oral care and dental intervention in reducing the effect of periodontal diseases and their effect on respiratory health1

  • Huang et al. observed that patients on intensive periodontal treatment had a 29% lower risk of pneumonia (hazard ratio = 0.71. 95% CI—0.65–0.78). 1
  • Adachi et al. evaluated the role of professional oral health care (POHC) by dental hygienists in reducing respiratory infections in elderly persons requiring nursing care. The relative risk of developing influenza while under POHC was found to be 0.1 (95% CI 0.01–0.81, P = 0.008). 1
  • Bassim et al. investigated the association between oral health care and risk factors for mortality from pneumonia and concluded that the odds of dying from pneumonia in the group that did not receive oral care was 3-folds higher than that of the group that did receive oral care (odds ratio = 3.57, P = 0.03). 1
  • Shi et al. in a Cochrane systematic review assessed the effects of oral health care on incidence of ventilator-associated pneumonia (VAP) in critically ill patients in intensive care units and concluded that effective oral health care is associated with 40% reduction in risk of developing VAP1


The role of periodontal diseases in causing pulmonary diseases is not well understood. There are several studies which have tried to establish the connection but has been deemed inconclusive. However the possibility of pulmonary infection can be considered by the dentists when the partients with periodontal infection starts exhibiting symptoms.


  1. Muthu J, et al. Periodontitis and Respiratory Diseases: What Does the Recent Evidence Point to?. Current Oral Health Reports. 2018;5(1):63-69.
  2. Chowdhary Z, et al. prevalence of periodontitis in patients with pulmonary disease: A cross-sectional survey in the industrial district of India. Journal of Indian Society of Periodontology. 2019;23(3):269.
  3. Bansal M, et al. Potential role of periodontal infection in respiratory diseases - a review. J Med Life. 2013 Sep 15;6(3):244-8.
  4. Verma U, et al. Periodontal diseases: A covert focus of inflammation in pulmonary diseases. Indian Journal of Respiratory Care. 2019;8(1):8.
  5. Scannapieco F, et al. Role of Oral Bacteria in Respiratory Infection. Journal of Periodontology. 1999;70(7):793-802.

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