Breaking down the microbiology world one bite at a time

The Role of Bacteria in Gum Disease: A Look at the Past and Present

Written by

Microbes are present everywhere in our body including the mouth. These tiny beings can be harmful as well as helpful to us. The harmful microbes can cause damage to the gum and lead to periodontal diseases. In this article, we will try to understand the etiology of these diseases. Etiology means how these microbes cause the disease or harm the gums. The bacteria in our mouth forms a layer on the gums and teeth, this is a bacterial biofilm known as plaque. This plaque can be one of the factors and that’s why we need to brush twice a day!

These microorganisms have virulence factors -the tools or weapons that can cause disease in the body. These “weapons” help them stick to cells, damage tissues, avoid the immune system, or steal nutrients from the body. There are two main bacteria that we are going to look into- one is Black pigmented anaerobes and the other is Aggregatibacter actinomycetemcomitans.

a) Black pigmenting anaerobes are bacteria that survive without oxygen and are often found in deep gum pockets. These bacteria produce a dark pigment and release harmful chemicals that break down the tissues and bones supporting the teeth. As they grow, they cause inflammation in the gums, leading to symptoms like swelling, bleeding, and bad breath. Over time, the damage weakens the gums and bones, making it easier for teeth to become loose or fall out. Because they thrive in areas with low oxygen, such as deep in the gums, they play a major role in causing periodontal (gum) disease.

b) Aggregatibacter actinomycetemcomitans affect the gums by producing toxins that directly damage the gum tissue and bone. These toxins lead to inflammation and destruction of the tissue supporting the teeth, causing symptoms like gum swelling, bleeding, and eventually tooth mobility. This bacterium is particularly aggressive and can contribute to a more severe form of periodontal disease. They thrive in low-oxygen environments, like deep gum pockets, and contribute to gum disease by creating a damaging environment that supports their growth.

Detection of periodontal diseases

Periodontal diseases are detected through a combination of dental exams and diagnostic tests. Dentists or periodontists check for signs of gum inflammation, bleeding, and pocket formation between the teeth and gums. They use a probe to measure the depth of these pockets—deeper pockets indicate more severe disease. X-rays are also used to check for bone loss around the teeth. In some cases, bacterial samples from the gum pockets are tested to identify specific pathogens, helping tailor treatment. Regular dental visits are key to early detection. Brushing and flossing regularly help remove plaque, the sticky film of bacteria on your teeth. Using an antibacterial mouthwash can also kill harmful bacteria. Regular dental visits are important too, as dentists can clean hard-to-reach areas and give tips on keeping your mouth healthy. If you have gum disease, treatment often starts with a deep cleaning procedure called scaling and root planing, where dentists remove plaque and tartar from below the gum line. In some cases, surgery might be needed to repair damage to the gums and bone. It’s also important to manage any other health problems, like diabetes, which can affect gum health. Regular follow-ups with your dentist help keep the disease under control and maintain good oral health.

Key bacteria causing periodontal diseases

Periodontal research has identified key bacterial taxa associated with advanced periodontal tissue destruction, including A. actinomycetemcomitans, C. rectus, P. gingivalis, P. intermedia, T. forsythia, and T. denticola. These bacteria contribute to periodontal disease by colonizing the gum tissues, forming biofilms, and triggering the host’s immune response. P. gingivalis, T. forsythia, and T. denticola release virulence factors, such as proteases and toxins, that degrade connective tissues and bone. A. actinomycetemcomitans produces leukotoxins, which kill white blood cells, weakening the immune response. C. rectus and P. intermedia produce inflammatory mediators that exacerbate tissue damage. The resulting inflammation leads to gum recession, bone resorption, and tooth loss, creating a vicious cycle of tissue destruction.

Initially, anaerobic culture techniques were the standard for detecting these pathogens, but DNA-based methods, like PCR, have replaced them. Microbial testing helps guide clinicians in selecting antimicrobial treatments for advanced periodontitis. However, variability in test performance and a broader focus on overall microbiome shifts rather than individual species may provide more accurate clinical information. Periodontitis is an infection-induced inflammatory disease, with microbial and host factors playing interconnected roles. Researchers have explored combining microbial and host biomarkers to improve diagnosis and treatment monitoring. Shifts in bacterial burden, inflammation, and tissue destruction occur sequentially, suggesting that both microbial and host markers should be evaluated together for accurate diagnosis. Studies have shown the cumulative use of biomarkers enhances diagnostic accuracy, but further validation in diverse populations is needed.

Role of antibiotics against periodontitis

Systemic antimicrobials, particularly Metronidazole and Amoxicillin, have been used as adjunctive treatments for periodontitis. Antibiotics help treat periodontitis by killing or stopping the growth of harmful bacteria that cause gum infections. When bacteria in the gums get out of control, they cause inflammation, pain, and tissue damage. Antibiotics reduce the number of these bacteria, allowing the body to heal. They are often used alongside other treatments, like deep cleaning, to help control infection. However, antibiotics alone aren’t enough—they work best when combined with proper dental care and good oral hygiene.These drugs target specific bacteria like A. actinomycetemcomitans and anaerobes found in deepened periodontal pockets. While adjunctive antibiotics improve clinical outcomes, especially in severe cases, concerns about antibiotic resistance have led to recommendations against routine use without microbial testing. Alternative options, such as Azithromycin for penicillin-allergic patients, are also being considered. However, the widespread use of systemic antibiotics remains controversial due to the potential for resistance, and their use is recommended only in specific cases.

Link to the original post: Belibasakis GN, Belstrøm D, Eick S, Gursoy UK, Johansson A, Könönen E. Periodontal microbiology and microbial etiology of periodontal diseases: Historical concepts and contemporary perspectives. Periodontol 2000. 2023 Jan 20. doi: https://doi.org/10.1111/prd.12473

Featured image: adapted from Vecteezy (Brushing Vectors by Vecteezy)