关注儿童齿健康(2)
一副好牙要从小保护，美国专家专注儿童齿健康【生词摘录】http://t1.g.hjfile.cn/voasp/rm/2007/03/20070317.mp3The use of fluoride to protect teeth is common in many parts of the world. This natural element is often added to drinking water supplies. The fluoride mixes with enamel, the hard surface on teeth, to help prevent holes, or cavities, from forming.But the American Academy of Pediatric Dentistry po…
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