By Linda Orlando People the world over have been paying attention to tooth care for centuries. The Babylonians used a chewing stick in 3500 B.C. to clean the teeth and mouth like a toothpick. The first toothbrush was invented by the Chinese in the 15th century, and early toothbrushes were made of stiff animal hair from wild boars and horses. The Egyptians were very concerned about dental hygiene, as evidenced by the fact that many Egyptians were buried with small tree branches that they used to clean their teeth. Taking care of teeth has long been a concern of civilized societies around the globe. You'd think that with today's modern technology, tooth care would be absolutely flawless, right? The truth is actually far from that-unless a toothbrush is kept sanitary, brushing your teeth may actually contribute to tooth decay and gum disease. And sanitizing means more than just rinsing the brush after you finish. Dr. Gary Westerman, of the Creighton University School of Dentistry in Omaha, assigned his first-year students a research project to demonstrate the effects of not cleaning a toothbrush properly. Westerman's students were told to test how much bacteria remains on a toothbrush after it has been rinsed off. "That bacteria's got to go someplace," Westerman said. "Most of it will be in the saliva, which we will ultimately rinse out or swallow. But some of it will be on the toothbrush." Most people put their toothbrush in a specially designed holder, set it on a counter, or stick it in a drawer. But as the project demonstrated, none of those options is sufficient for keeping the brush clean. The evidence was clear in the petrie dishes of Westerman's experiment. After just 24 hours of incubation, one student's brush contained over 2,000 bacterial colonies. "This is pretty typical," said student Shannon Sena. "We had 14 samples that I counted yesterday, and they were all in the ballpark of this, about 2,000 colonies per person." Westerman said that although that much bacteria shouldn't make you sick, it can cause tooth decay and gum disease. The bacteria just sits right there waiting for you, to affix itself to your teeth the next time you brush. But there are ways to sanitize a toothbrush to prevent the bacteria from hanging around. One group of Westerman's students tried soaking brushes for 10 minutes in an antibacterial mouth rinse after use. Part of the group used Listerine, and another used Peridex, a rinse available only by prescription. A third group of students placed their toothbrushes in a Violight toothbrush sanitizer, which sells for about $30 and is marketed as being able to kill "up to 99.9% of the bacteria" in 7 minutes. Westerman questioned the validity of those claims, asking "The light shines on the bristles, but how far down on the toothbrush does it go? And did it really get all the bacteria on the head of the toothbrush?" Surprisingly, the results of the tests showed that all three methods were pretty equal in how well they sanitized the brushes. The Listerine and Peridex treatments both killed 98-99% of the bacteria, and so did the Violight. So paying $30 for an electronic cleaner or maybe more for a prescription rinse isn't necessary; plain old Listerine will work just as well. Westerman's research project showed that toothbrushes should be sanitized after each use, and then allowed to air dry. Don't' store a brush inside a drawer, or in a cover that may trap the bacteria inside. And there's no need to soak the brush for hours in an antibacterial rinse-10 minutes is enough, and then let it air dry. Whether you use a manual or electric toothbrush, dentists say you should change the brush every three months or so to keep that smile white and healthy.