Dental Anti-biofilm Sealants

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        Tech Doc: Tools allow us to live with bacterial travelers

        September 17, 2013 – 12:02am

        The human body is covered with bacteria. In fact, if the bacteria living inside the body are included, humans contain more bacteria than cells.

        While bacteria are our friends, they can also become our enemies. The key is to keep them in check so they cannot gain control. These days we are constantly bombarded with articles on the importance of eating probiotics to maintain a good ecosystem of bacteria in our intestines. However, when the system gets out of whack, we can have problems with these tiny organisms that live with us.

        If you cut yourself, you allow bacteria to proliferate that ordinarily would not be a problem. This is especially true if you have a larger, slow-healing wound or a burn. This gives bacteria growing conditions to form a biofilm. Biofilms are complex structures that result when bacteria bind to an open wound and form a film. Other types of bacteria also bind to the site and start to form what looks like a piece of skin. Once a biofilm starts to form it is hard to kill. Biofilms are tough and present a surface difficult for antibodies and blood cells to attack.

        Under conditions where food supply is low, bacteria tend to bind to a surface and form biofilms where they can live for a long time. For example, mountain streams have few bacteria in the water, but slippery rocks are covered with biofilms. Biofilms are a common way for bacteria to survive. The big problem is if they are not growing fast and they are covered with a slime that is difficult to penetrate; this makes them difficult to treat with antibiotics and hard to reach by blood cells.

        Antibiotics require growing bacteria and have trouble penetrating the slime. Also, although it may be possible to kill the bacteria on the surface of the biofilm, the core bacteria continue to live. Bacteria in a biofilm also can release toxins that can make you sick.

        Ordinarily, we do not have biofilms in our body because if they try to attach to a living cell, they can be eaten by the cell. Thus, there are few places for them to attach. One of the few places is on teeth. This bacterial biofilm is called plaque. Bacterial plaque can slowly eat away at our teeth from the acid produced from the bacteria.

        Fortunately, we have been able to develop a material at the Texas Tech Health Sciences Center called SeLect Defense that coats teeth to inhibit plaque formation. Currently, dentists can coat teeth with a sealant that helps protect against the acid produced by the bacteria of a plaque. However, plaque can form on this sealant.
        We have recently developed a sealant in conjunction with a Lubbock orthodontics company, Element 34, that contains an organo-selenium compound that makes the sealant inhibit plaque formation. Other members of the TTUHSC team that helped develop and test this sealant were Abdul Hamood, Ph.D., and Phat Tran, Ph.D. A paper outlining selenium and plaque formation was recently published in the “Journal of Dental Research.”

        After development, this selenium sealant was sent to Bennett Amaechi, BDS, at the University of Texas School of Dentistry in San Antonio. Amaechi put SeLect Defense on half the teeth of 120 patients. On the other half of the teeth he put sealant without selenium. After one year, he found 95 percent tooth surface was still covered by the selenium sealant and there was no plaque on the selenium sealant. However, on the teeth with sealant without selenium, there was plaque.

        The reason that the selenium-containing polymer, applied to the teeth, inhibited bacterial biofilm formation is because of a special property of the element selenium. Selenium catalyzes the formation of superoxide radicals by taking an electron from the sulfur compounds in saliva and giving it to oxygen. This catalytic mechanism continues as long as the selenium compound remains in the sealant. Since the selenium is chemically bonded to the polymer, the action lasts as long as the sealant stays on the tooth.

        Since solid materials inserted into or on the body can be a location where biofilms can form, we are in the process of developing selenium-containing polymers for these medical devices. We are testing new polymers for contact lenses and catheters. Future plans are to develop the ability to incorporate selenium into all medical devices like heart valves, joint replacements, intraocular lenses, glaucoma valves, tympanostomy tubes and bandages.

        TEDD REID

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