Why Plaque Is More Dangerous Than You Think?

Chronic infections are composed of bacterial biofilms that can persist in and on our bodies for many years. But, biofilms are not constrained to chronic infections; they are present in several spaces in the healthy human body and basically everywhere in your surrounding.

Human Microbiome:

The human microbiome organized in the form of biofilms is known as Commensal Biofilms. The number of bacterial cells in the human body is ten times more than the total number of human cells. And if we talk about bacterial genes they constitute about 99% of total genes in the human body.

Commensal and natural biofilms are more diverse than chronic biofilms. These biofilms facilitate vital processes including the degradation of organic matter and facilitate plant growth.

ORAL BIOFILMS:

The oral cavity harbors hundreds of microbial species that are present either as planktonic cells or incorporated into biofilms. The majority of the oral microbes are commensal organisms. Those that are pathogenic microbes can result in oral infections, and at times can initiate systemic diseases.

There are two major types of oral biofilms:

1. Dental Biofilms/ Plaque
2. Carogenic Biofilms

Dental Plaque:

Dental plaque is associated with caries and periodontal disease. But they also have some beneficial effects. Like:

1. Natural defense through the microbiome. The host microbiome act as a barrier to pathogens.
2. Protect teeth from erosion, which is de-mineralization of the teeth due to intake of fizzy acidic drinks.

700 bacterial species are present in oral biofilms, of which only 10% constitute 90 to 95%. Biofilms form on several surfaces like the tongue and teeth. They vary in location due to environmental conditions such as pH, energy, Oxygen, etc. Oral biofilms are most widespread on teeth because it's not shredding surfaces like mucosa. If biofilm is left undisturbed it can cover teeth in 2 days and will be visible in 4 days.

Bacteria don't attach directly to the tooth cuz of the enamel surface is covered by a layer of salivary proteins called Pellicles. The first bacteria to adhere to is oral streptococci. Facultative Actinomyces acts as a receptor for other bacteria. Fusobacterium play a key role because it can aggregate with all bacteria in the biofilm. Biofilms develop from gram-positive to gram-negative rods and cocci.

Environmental factors affect biofilms. It is described by PHILLIP MARSH in a hypothesis called the ECOLOGICAL PLAQUE HYPOTHESIS, which states:

Change in ecological factors like access to growth factors, oxygen,pH and amount of gingival crevicular fluid determine the composition of the biofilm.

Carogenic biofilms:

Carogenic biofilms are described as microbial communities that create their own localized pH niche. These biofilms are dominated by 2 pathogens mainly:

1. Mutant Streptococci: It has a strong ability to adhere tooth due to sugar metabolism. It produces acid and can live at low pH.
2. Lactobacilli: It is found in already established lesions and is highly aciduric.

Diseases caused by oral biofilms:

Caries:   Caries also known as cavities/demineralization is caused by biofilm production due to a drop in pH to 5.5. This drop in pH is due to acid production by fermentation. Caries allow bacteria to go to the pulp where nerves are located. Bacteria then induce inflammation and pain due to which pulp tissue becomes infected leading to necrosis. Due to necrosis nutrients convert from carbohydrates to proteins and the environment becomes more anaerobic.

An anaerobic environment favors the growth of proteolytic bacteria that spread from the root canal to the apical area of the tooth and jawbone. Biofilms in the pulp area are hard to identify.

Gingivitis:   Gum becomes swollen and red and may bleed. If not treated it can progress to periodontitis that lead to tooth loss.

Peridontitis:   Peridontitis is the loss of supporting tissue around teeth that result in the loosening of teeth.

Creator: Gunita Reine 

Other Factors:

Other factors that can be a cause of oral biofilms are Dentures and Implants.

People who wear dentures usually have biofilms that contain Candida albicans, a pathogenic fungus that lives on the polymethyl acrylate used to make dentures (PMA). Denture wearers are at risk for denture stomatitis, an inflammation of the oral tissues that contribute to poor oral health, poor dental hygiene, and systemic diseases like diabetes.

Dental implants are man-made structures that replace lost teeth. They are constructed of plastic and titanium. Implant-related infections and inflammation can occur in patients who have them. The implant-related bacteria may gather and create a biofilm. The roughness of the implant's surface may alter bacterial adhesion to the implant and promote the development of biofilms. Peri-implantitis is an inflammatory condition that harms the oral tissue that supports the implant.

Conclusion: 

• Gingivitis is mediated by the amount of bacteria in biofilm while caries & peridontitis are mediated by changes in the environment that favor the growth of pathogenic species. 
• Caries develop due to a decrease in pH while periodontitis develops due to an increase in pH.