Oral ecology
Encyclopedia
Adult mouths may contain 500 to 1,000 different types of bacteria
as part of the human flora and oral microbiology
, but about 100 to 200 species may live in them at any given time. Those who care for their teeth and have a relatively clean mouth have 1,000 to 100,000 bacteria living on each tooth surface. Those that do not have a clean mouth have between 100 million and 1 billion bacteria on each tooth. Each day more bacteria grow in a person’s mouth. Though bacteria and saliva can be beneficial to one’s health, both can also cause problems. Many diseases are related to oral bacteria. While bacteria will always be in our mouths, proper oral care and habits can protect against and reduce the effects of some harmful bacteria.
in the 17th century. Leeuwenhoek, a Dutch scientist, performed many experiments testing and observing bacteria. He observed plaque on his own teeth— “a little white matter” as he called it. Under microscopes he saw “that in the said matter there were many very little living animalcules, very prettily a-moving,” which was the first sighting of oral bacteria as we know it. Leeuwenhoek tested the mouths of others, as well as his own. Two men that he tested had never cleaned their teeth in their lives and Leeuwenhoek found “an unbelievably great company of living animalcules…in such enormous numbers, that all the water…seemed to be alive.” Thus Leeuwenhoek discovered oral bacteria or “animalcules,” the name he gave bacteria in general.
Later studies have shown that he actually saw mats of bacteria, what we know today as biofilms. Biofilms are communities of bacteria, or micro-organisms
, attached to surfaces in the body. Oral biofilms are more commonly referred to as plaque. Biofilms form almost everywhere where there is bacteria. In the mouth, they naturally form on any stationary surface, namely teeth, gums, and the tongue. Leeuwenhoek made important findings of bacteria with his first observation and analysis of dental plaque
, and since then much more has been discovered about the mouth and its ecology.
make up a large majority of what affects our mouths. As a matter of fact, it is “the biggest culprit in tooth decay” as it promotes the production of acids and enzymes. The acids cause the collapse of enamel opening the door for the formation of decay. The enzymes “leach down the tooth and begin to dissolve the ligaments and bone that help to hold the teeth in your mouth.” By turning simple sugars
and carbohydrates into acids and enzymes that dissolve tooth enamel
, this bacteria can leave a person with lasting dental problems. According to Dr. Robert Gandola, a dentist, “A number of bacteria can cause decay [and many] are suspected in periodontal (gum) disease.”
As mentioned, oral bacteria also help fight disease-producing germs that try to come in through the mouth. These bacteria work with our immune system
to keep our bodies disease free. For example, some of these bacteria produce organic acid
s that kill the organisms that cause intestinal problems. Without these good bacteria, our immune systems would be constantly bombarded by airborne and saliva-transferred germs. Bacteria are also needed to control the growth of fungus. “Balance between all the different bacteria and fungus are critical” or else the “fungus overgrows and takes over.” So, ironically, though bacteria have the potential to harm us, our mouth and the good bacteria in it are the body’s first line of defense.
in short periods of time, it can quickly and easily create biofilms. Third, the biofilm matures and accumulates more mass on the surface. Bacteria can continue to divide and grow by binary fission until nutrients begin to run out or their growth is inhibited. When this happens there is the final stage, the dispersal or detachment, causing the death of the bacteria. Some oral bacteria, streptococcus gordonii for example, cannot last for long periods without nutrients, while other types of bacteria can survive for weeks. While in their prime, biofilms can cause major damage to a person’s teeth and gums. Though damaging, biofilms can be partly removed by brushing and flossing and “some of it comes off with rinsing or eating.” We never really lose all of it because it is constantly being replenished by our own saliva. Bacteria can then reattach and start to grow and the cycle continues. Bacteria and its growth are two of the principal components of oral ecology.
The main function of saliva is to flush out all of the micro-organisms that could potentially threaten our health. The flow of saliva constantly bathes the mouth and detaches all micro-organisms that are not already firmly attached to a surface. This makes it difficult for bacteria to adhere to surfaces to even begin to form biofilms. Many harmful micro-organisms, therefore, are unable to attach quick enough to a surface before they are caught in saliva and swallowed. Although saliva does a lot to keep our bodies healthy, it cannot completely keep all bacteria from adhering to tooth, tongue or gum surfaces.
or canker sores
), flu virus, cold virus
, and various bacteria that cause periodontal disease
(inflammation or infection of gum tissue), venereal diseases
, and candida albicans
(fungus).
Mononucleosis (mono), known among teenagers as the “kissing disease”, is another prominent condition that can come from saliva exchange. It is a contagious viral disease
in the herpes virus
family. In addition to kissing, however, mono can also “be spread when a person coughs, sneezes, or shares objects such as drinking glass or water bottles.” There are only certain stages when it is contagious,mostly during the fever stage, but during those times it is transferrable through saliva exchange.
. These diseases are not passed through saliva, but are still influenced by the mouth’s ecology and bacteria. Streptococcus mutans, a common oral bacteria discussed above, is a pathogen that causes pneumonia, sinusitis, otitis media
, and meningitis.
Diet has an influence in our oral health as well. Most of us have been warned against eating too much candy because it will give us cavities. This is true because much of the bacteria in our mouths are nourished by simple sugars and carbohydrates. An excess of candy, soda, or other simple sugars is an easy way to let bacteria thrive in our mouths. In addition, there are other ways to further reduce the risk of invaders harming the mouths’ health. Visits to the dentist can be beneficial where fluoride treatments are available. Combined with dental sealant
s, these treatments can, in most cases, ensure prevention of harmful bacterial effects. Fluoride is extremely effective in protecting enamel on the teeth. “Fluoride, a chemical that appears naturally in groundwater in many areas of the world, quickly bonds with the tooth's enamel to maintain its smooth crystalline surface and deter bacteria from gaining a toehold.” The Oral-B website advises people to “drink tap water
when possible” because “if bottled water
is your main source of drinking water, you could be missing the decay-preventative benefits of fluoride.” Also, a study in the Journal of the American Dental Association
states that “antiseptic mouthwashes have been associated with a 28 to 34 percent reduction in dental plaque biofilms at six month follow-ups. Chlorhexidine gluconate
[mouthwash] rinses, when combined with toothbrushing, have been reported to reduce oral biofilms . . . by 50 to 55 percent.” By going to do the dentist and listening to advice, one can begin to prevent oral infection and disease.
s. Much of the bacteria will be killed off using these methods, either when exposed to cleansing agents or air, but also increase the possibility of damaging the toothbrush in the process. Though cleaning a toothbrush will ensure that the small amount of bacteria left on it will be killed, the American Dental Association advises that one should replace a toothbrush every three to four months. The Journal of the American Dental Association suggests a few “common-sense” ways to stay healthier in relation to toothbrush care: “don’t share toothbrushes, thoroughly rinse the toothbrush with tap water after use to remove any toothpaste and debris, store the toothbrush in an upright position if possible and allow it to air-dry, when storing more than one brush, keep them separated so that germs are not transferred from one brush to another, and don’t routinely cover or store toothbrushes in closed containers. A moist environment helps the growth of most germs.” By taking care of one’s toothbrush, sicknesses from bacteria can be greatly reduced.
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
as part of the human flora and oral microbiology
Oral microbiology
Oral microbiology is the study of the microorganisms of the oral cavity and the interactions between the oral microorganisms with each other and with the host. Of particular interest is the role of oral microorganisms in the two major dental diseases: dental caries and periodontal disease.The mouth...
, but about 100 to 200 species may live in them at any given time. Those who care for their teeth and have a relatively clean mouth have 1,000 to 100,000 bacteria living on each tooth surface. Those that do not have a clean mouth have between 100 million and 1 billion bacteria on each tooth. Each day more bacteria grow in a person’s mouth. Though bacteria and saliva can be beneficial to one’s health, both can also cause problems. Many diseases are related to oral bacteria. While bacteria will always be in our mouths, proper oral care and habits can protect against and reduce the effects of some harmful bacteria.
Discovery and History of Bacteria
Bacteria were first detected under the microscopes of Antony van LeeuwenhoekAnton van Leeuwenhoek
Antonie Philips van Leeuwenhoek was a Dutch tradesman and scientist from Delft, Netherlands. He is commonly known as "the Father of Microbiology", and considered to be the first microbiologist...
in the 17th century. Leeuwenhoek, a Dutch scientist, performed many experiments testing and observing bacteria. He observed plaque on his own teeth— “a little white matter” as he called it. Under microscopes he saw “that in the said matter there were many very little living animalcules, very prettily a-moving,” which was the first sighting of oral bacteria as we know it. Leeuwenhoek tested the mouths of others, as well as his own. Two men that he tested had never cleaned their teeth in their lives and Leeuwenhoek found “an unbelievably great company of living animalcules…in such enormous numbers, that all the water…seemed to be alive.” Thus Leeuwenhoek discovered oral bacteria or “animalcules,” the name he gave bacteria in general.
Later studies have shown that he actually saw mats of bacteria, what we know today as biofilms. Biofilms are communities of bacteria, or micro-organisms
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
, attached to surfaces in the body. Oral biofilms are more commonly referred to as plaque. Biofilms form almost everywhere where there is bacteria. In the mouth, they naturally form on any stationary surface, namely teeth, gums, and the tongue. Leeuwenhoek made important findings of bacteria with his first observation and analysis of dental plaque
Dental plaque
Dental plaque is a biofilm, usually a pale yellow, that develops naturally on the teeth. Like any biofilm, dental plaque is formed by colonizing bacteria trying to attach themselves to a smooth surface...
, and since then much more has been discovered about the mouth and its ecology.
Ecology and Types of Bacteria Found in the Mouth
As previously stated, the human mouth contains around 500 to 1000 types of bacteria that have various functions. While some of the bacteria in our mouths are harmful and can cause serious illness, much of our oral bacteria are actually beneficial in preventing disease. Streptococci make up a large part of oral bacteria. There are four main species within streptococci: the mutans, salivarius, anginosus, and mitis groups. Streptococcus mutansStreptococcus mutans
Streptococcus mutans is a facultatively aerobic, Gram-positive coccus-shaped bacterium commonly found in the human oral cavity and is a significant contributor to tooth decay.The microbe was first described by J Kilian Clarke in 1924.-Introduction:...
make up a large majority of what affects our mouths. As a matter of fact, it is “the biggest culprit in tooth decay” as it promotes the production of acids and enzymes. The acids cause the collapse of enamel opening the door for the formation of decay. The enzymes “leach down the tooth and begin to dissolve the ligaments and bone that help to hold the teeth in your mouth.” By turning simple sugars
Monosaccharide
Monosaccharides are the most basic units of biologically important carbohydrates. They are the simplest form of sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose , fructose , galactose, xylose...
and carbohydrates into acids and enzymes that dissolve tooth enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
, this bacteria can leave a person with lasting dental problems. According to Dr. Robert Gandola, a dentist, “A number of bacteria can cause decay [and many] are suspected in periodontal (gum) disease.”
As mentioned, oral bacteria also help fight disease-producing germs that try to come in through the mouth. These bacteria work with our immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
to keep our bodies disease free. For example, some of these bacteria produce organic acid
Organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...
s that kill the organisms that cause intestinal problems. Without these good bacteria, our immune systems would be constantly bombarded by airborne and saliva-transferred germs. Bacteria are also needed to control the growth of fungus. “Balance between all the different bacteria and fungus are critical” or else the “fungus overgrows and takes over.” So, ironically, though bacteria have the potential to harm us, our mouth and the good bacteria in it are the body’s first line of defense.
Bacterial Growth
Numerous kinds of bacteria grow in the mouth. “They are competing for food and places to grow” and the many hard surfaces in the mouth provide an ideal place for bacteria and biofilms to grow and reproduce. Unlike most other places in or on the body, the mouth does not desquamate (shed). A tooth’s distinct surface and stagnant nature makes it optimal for populations and growth of micro-organisms and bacteria, resulting in dental plaque. To grow and flourish in the mouth, biofilms go through four main stages of growth. First, bacteria must be deposited from saliva onto a surface where it can attach. Then the bacteria, or micro-organisms, grow and replicate. Since bacteria can grow exponentiallyExponential growth
Exponential growth occurs when the growth rate of a mathematical function is proportional to the function's current value...
in short periods of time, it can quickly and easily create biofilms. Third, the biofilm matures and accumulates more mass on the surface. Bacteria can continue to divide and grow by binary fission until nutrients begin to run out or their growth is inhibited. When this happens there is the final stage, the dispersal or detachment, causing the death of the bacteria. Some oral bacteria, streptococcus gordonii for example, cannot last for long periods without nutrients, while other types of bacteria can survive for weeks. While in their prime, biofilms can cause major damage to a person’s teeth and gums. Though damaging, biofilms can be partly removed by brushing and flossing and “some of it comes off with rinsing or eating.” We never really lose all of it because it is constantly being replenished by our own saliva. Bacteria can then reattach and start to grow and the cycle continues. Bacteria and its growth are two of the principal components of oral ecology.
Saliva
Though bacteria play a major role in oral ecology, another key part is saliva. Saliva keeps the ecosystem of our mouth in balance. It contains its own bacterial enzymes that are beneficial to our health. An example of these are lysozomes. These antibacterial agents in saliva kill bacteria in our mouths and protect from potentially dangerous diseases. In addition, saliva contains phosphate and calcium ions that help repair microscopic chinks made in the teeth by the bacteria’s acid. The major organic constituents of saliva are proteins and glycoproteins. Proteins in saliva float around and influence the mouth’s ecosystem in multiple ways. Some of the proteins provide nutrients for bacteria, while others cause bacteria to clump together so they are unable to stick to any surface and are washed away.The main function of saliva is to flush out all of the micro-organisms that could potentially threaten our health. The flow of saliva constantly bathes the mouth and detaches all micro-organisms that are not already firmly attached to a surface. This makes it difficult for bacteria to adhere to surfaces to even begin to form biofilms. Many harmful micro-organisms, therefore, are unable to attach quick enough to a surface before they are caught in saliva and swallowed. Although saliva does a lot to keep our bodies healthy, it cannot completely keep all bacteria from adhering to tooth, tongue or gum surfaces.
Diseases Transmitted Through Saliva
Because of the amount of bacteria in each person’s mouth, there is a transfer of bacteria through saliva when chapstick, drinks, toothbrushes, or anything else is shared. Some of these viruses that result are relatively inconsequential while others could potentially have a serious impact on one’s life. Some examples of the milder diseases passed through saliva include herpes simple virus (cold soresHerpes simplex virus
Herpes simplex virus 1 and 2 , also known as Human herpes virus 1 and 2 , are two members of the herpes virus family, Herpesviridae, that infect humans. Both HSV-1 and HSV-2 are ubiquitous and contagious...
or canker sores
Aphthous ulcer
An aphthous ulcer , also known as a canker sore, is a type of mouth ulcer which presents as a painful open sore inside the mouth or upper throat characterized by a break in the mucous membrane. Its cause is unknown, but they are not contagious...
), flu virus, cold virus
Common cold
The common cold is a viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a cough, sore throat, runny nose, and fever...
, and various bacteria that cause periodontal disease
Periodontal disease
Periodontitis is a set of inflammatory diseases affecting the periodontium, i.e., the tissues that surround and support the teeth. Periodontitis involves progressive loss of the alveolar bone around the teeth, and if left untreated, can lead to the loosening and subsequent loss of teeth...
(inflammation or infection of gum tissue), venereal diseases
Sexually transmitted disease
Sexually transmitted disease , also known as a sexually transmitted infection or venereal disease , is an illness that has a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex...
, and candida albicans
Candida albicans
Candida albicans is a diploid fungus that grows both as yeast and filamentous cells and a causal agent of opportunistic oral and genital infections in humans. Systemic fungal infections including those by C...
(fungus).
Mononucleosis (mono), known among teenagers as the “kissing disease”, is another prominent condition that can come from saliva exchange. It is a contagious viral disease
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
in the herpes virus
Herpes virus
In colloquial use, herpes virus refers to the herpes simplex virus, particularly when transmitted sexually.In scientific use, herpesvirus refers to a virus of the taxonomic family herpesviridae....
family. In addition to kissing, however, mono can also “be spread when a person coughs, sneezes, or shares objects such as drinking glass or water bottles.” There are only certain stages when it is contagious,mostly during the fever stage, but during those times it is transferrable through saliva exchange.
Diseases Related to Oral Hygiene
Other serious and possibly life-threatening diseases have been found to be connected to oral hygieneOral hygiene
Teeth cleaning is part of oral hygiene and involves the removal of dental plaque from teeth with the intention of preventing cavities , gingivitis, and periodontal disease. People routinely clean their own teeth by brushing and interdental cleaning, and dental hygienists can remove hardened...
. These diseases are not passed through saliva, but are still influenced by the mouth’s ecology and bacteria. Streptococcus mutans, a common oral bacteria discussed above, is a pathogen that causes pneumonia, sinusitis, otitis media
Otitis media
Otitis media is inflammation of the middle ear, or a middle ear infection.It occurs in the area between the tympanic membrane and the inner ear, including a duct known as the eustachian tube. It is one of the two categories of ear inflammation that can underlie what is commonly called an earache,...
, and meningitis.
Prevention
Although disease is possible through oral interactions, there are many ways to prevent or at least reduce the risk of infection and disease. Brushing and flossing teeth regularly are the most basic ways to reduce these risks. These two fundamental hygiene tips help to get rid of bacteria that try to stick to surfaces in our mouth to form plaque (oral biofilms). Brushing and flossing the teeth are critical because they disrupt biofilms and their ability to permanently damage the teeth or gums. The less you brush your teeth, the better chance that bacteria will form plaque and potentially cause serious oral and health issues.Diet has an influence in our oral health as well. Most of us have been warned against eating too much candy because it will give us cavities. This is true because much of the bacteria in our mouths are nourished by simple sugars and carbohydrates. An excess of candy, soda, or other simple sugars is an easy way to let bacteria thrive in our mouths. In addition, there are other ways to further reduce the risk of invaders harming the mouths’ health. Visits to the dentist can be beneficial where fluoride treatments are available. Combined with dental sealant
Dental sealant
Dental sealants are a dental treatment consisting of applying a plastic material to one or more teeth, for the intended purpose of preventing dental caries or other forms of tooth decay.-Development:...
s, these treatments can, in most cases, ensure prevention of harmful bacterial effects. Fluoride is extremely effective in protecting enamel on the teeth. “Fluoride, a chemical that appears naturally in groundwater in many areas of the world, quickly bonds with the tooth's enamel to maintain its smooth crystalline surface and deter bacteria from gaining a toehold.” The Oral-B website advises people to “drink tap water
Tap water
Tap water is a principal component of "indoor plumbing", which became available in urban areas of the developed world during the last quarter of the 19th century, and common during the mid-20th century...
when possible” because “if bottled water
Bottled water
Bottled water is drinking water packaged in plastic or glass water bottles. Bottled water may be carbonated or not...
is your main source of drinking water, you could be missing the decay-preventative benefits of fluoride.” Also, a study in the Journal of the American Dental Association
American Dental Association
The American Dental Association is an American professional association established in 1859 which has more than 155,000 members. Based in Chicago, the ADA is the world's largest and oldest national dental association and promotes good oral health to the public while representing the dental...
states that “antiseptic mouthwashes have been associated with a 28 to 34 percent reduction in dental plaque biofilms at six month follow-ups. Chlorhexidine gluconate
Chlorhexidine gluconate
Chlorhexidine is a chemical antiseptic. It is effective on both Gram-positive and Gram-negative bacteria, although it is less effective with some Gram-negative bacteria. It has both bactericidal and bacteriostatic mechanisms of action, the mechanism of action being membrane disruption, not ATPase...
[mouthwash] rinses, when combined with toothbrushing, have been reported to reduce oral biofilms . . . by 50 to 55 percent.” By going to do the dentist and listening to advice, one can begin to prevent oral infection and disease.
Toothbrush Hygiene
There are many ways to improve the oral cleaning process. One basic and obvious way is to make sure the toothbrush is clean. Some dentists recommend methods of cleaning, such as putting toothbrushes in dishwashers or microwave ovenMicrowave oven
A microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...
s. Much of the bacteria will be killed off using these methods, either when exposed to cleansing agents or air, but also increase the possibility of damaging the toothbrush in the process. Though cleaning a toothbrush will ensure that the small amount of bacteria left on it will be killed, the American Dental Association advises that one should replace a toothbrush every three to four months. The Journal of the American Dental Association suggests a few “common-sense” ways to stay healthier in relation to toothbrush care: “don’t share toothbrushes, thoroughly rinse the toothbrush with tap water after use to remove any toothpaste and debris, store the toothbrush in an upright position if possible and allow it to air-dry, when storing more than one brush, keep them separated so that germs are not transferred from one brush to another, and don’t routinely cover or store toothbrushes in closed containers. A moist environment helps the growth of most germs.” By taking care of one’s toothbrush, sicknesses from bacteria can be greatly reduced.