Tuesday, October 22, 2013

How dangerous are dental cavities?

A fungus and a bacteria team up to cause oral diseases, knock out human teeth and much more.

Dental disease is a global problem affecting up to 90% of all adults. In the U.S. 42% of children by the age of 11 have had cavities. Oral crevices and empty spaces along with different tissue types such as the tongue and mucous surfaces, a steady supply of saliva and any snacks and foods that go into the mouth support a complex microbial flora that may comprise of over 700 different bacterial species, according to a a new study published on the online journal PLOSPathogens.

Almost 300 of these microbes contribute to the periodontic pocket biofilm. Of these the predominant bacterium is Streptococcus Mutans that resides on the enameled surfaces and is responsible for most of the cavity formation and periodontal disease.

Living in dental plaque this bacteria can metabolize any sugar converting glucose, lactose, fructose and other starches into lactic acid, adding to tooth surface vulnerability, but it has a dual use for sucrose, the main table sugar. S. Mutans converts it to dextran which helps to generate a protective matrix of exopolysaccharide within which cells can mutliply, while the dextran also provides a reserve food supply for the bacteria. This biofilm covers both teeth and surrounding gingival tissues exposing them to microbial assault.

The lactate produced by oral bacteria is ideal for Candida Albicans, the fungus that customarily resides in the human gut. Feeding on the lactic acid this microbe lowers oxygen levels creating a more favorable environment for the anaerobic S. Mutans to thrive in. It is no wonder both pathogens cling to each other as seen in electron microscopic images. Between the two destructive organisms teeth become highly vulnerable to cavities, periodontitis, gingivitis, and many other oral diseases.

Oral streptococci are not benign. If they get into the bloodstream S. Mutans can infect the heart valves causing lethal endiocarditis, while another inhabitant of dental plaque, Streptococcus gordonii, can masquerade as a protein that can trigger blood clots that could promote growth on heart valves or cause blocked blood vessels leading to stroke or damage to the heart muscle. This is a serious condition with 30% of infected patients dying due to these infections.

C. Albicans fungus is no stranger to humans. It resides in the gut of up to 80% of individuals and remains relatively harmless unless dietary preferences and excessive use of antibiotics kills off enough friendly bacteria at which point the fungus grows rapidly in absence of competing microbes. It can be particularly dangerous in immuno-compromised individuals and people who have HIV, undergoing chemotherapy or bone marrow transplant patients. It may show up on the tongue as thrush and affect nails and genitals as a yeast infection. It is commonly also found in mouths of people who have oral piercings. It can also be transmitted sexually.


Studies on children have borne out the synergistic relationship between Candida Albicans and Streptococcus Mutans where the fungus was discovered to be highly prevalent in young people with cavities.

Sources:

Metwalli KH, Khan SA, Krom BP, Jabra-Rizk MA (2013) Streptococcus mutans,Candida albicans, and the Human Mouth: A Sticky Situation. PLoS Pathog 9(10): e1003616. doi:10.1371/journal.ppat.1003616 Editor: Joseph Heitman, Duke University Medical Center, United States of America Published: October 17, 2013

Wikipedia, the free encyclopedia. "Periodontal pathogen." Accessed October 22, 2013. http://en.wikipedia.org/wiki/Periodontal_pathogen.


Wikipedia, the free encyclopedia. "Streptococcus mutans." Accessed October 22, 2013. http://en.wikipedia.org/wiki/Streptococcus_mutans


Wikipedia, the free encyclopedia. "Candida albicans." Accessed October 22, 2013. http://en.wikipedia.org/wiki/Candida_albicans


National Center for Biotechnology Information. "Genital colonisation and infection with candida in heterosexual and homosexual males." Accessed October 22, 2013. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1195901/


University of Rochester Medical Center (2011, June 28). How cavity-causing microbes invade heart. ScienceDaily. Retrieved October 22, 2013, from http://www.sciencedaily.com­ /releases/2011/06/110627095650.htm


Society for General Microbiology (2012, March 26). Dental plaque bacteria may trigger blood clots. ScienceDaily. Retrieved October 22, 2013, from http://www.sciencedaily.com­ /releases/2012/03/120326113436.htm




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