眼
下，各大产商正在大力宣传那些能够强化牙釉质的牙膏。据厂家介绍，这类牙膏能够加固牙齿的保护层，提高牙齿对食物和饮料中酸性物质侵蚀的抵抗能力。常见的含酸食品包括苏打水、橙汁和各种酸腌菜。不过，专家同时表示，虽然此类牙膏确实能提高牙釉质的耐酸性，但如果你整天狂饮苏打水的话，牙膏也是没有用的。
F. Martin Ramin for The Wall Street Journal
每个人的牙齿都容易受到酸侵蚀的危害，而唾液能够中和并带走部分酸性物质。可是，随着年龄的增加，由于唾液分泌减少，酸侵蚀的问题就会变得越来越严重。此外，某些药物也会减少唾液的分泌。
目前，市场上有多种牙膏声称自己能有效对抗酸侵蚀并加固牙釉质。据说，佳洁士（Crest）“健康专家”（Pro-Health）系列的“牙釉质防护盾”（Enamel Shield）可以“保护牙齿免受酸性物质的侵蚀”。而葛兰素史克公司（GlaxoSmithKline）生产的舒酸定（Sensodyne ProNamel）抗敏牙膏则能“有效对抗酸侵蚀”。高露洁（Colgate）全效（Total）系列中包括一款可以“加固牙釉质”的牙膏。而CVS药店的自有品牌牙膏则“含有能加固牙釉质的防酸配方”。
据专家介绍，上述牙膏通常都含氟化物，氟可以和口腔中的矿物质合成一种名为氟磷灰石（fluorapatite）的晶体，这种晶体通常覆盖在牙齿表面。而包括佳洁士“牙釉质防护盾”、舒酸定以及Squigle公司的Enamel Saver在内的一些牙膏均含有特殊配方，能减少牙齿的磨损，让你在刷牙时不会将牙釉质刷掉（Squigle是一家小品牌牙膏制造商，旗下产品据说对口腔没有刺激）。
对于厂家所宣称的种种功效，专家们意见不一。在专家看来，“牙膏可以强化牙釉质”的说法并不正确，因为牙膏本身不会令牙齿更加坚固。剪切力是衡量牙齿坚固程度的一个指标，指的是牙齿咬下食物（比如爆米花）时所释放的力量。而在加州大学旧金山分校牙医学院（University of California School of Dentistry in San Francisco）的院长费瑟斯通（John Featherstone）看来，此类产品确实能增强牙齿表面抵抗食物中酸性物质的能力。
虽然牙医们承认这些牙膏有助于牙釉质的保护，但你饮用酸性饮料的时候还是应该适可而止。纽约大学（New York University）牙医学院龋病学和口腔综合治疗系主任沃尔夫（Mark S. Wolff）教授说，你不能一边狂饮酸性饮料，一边指望牙膏来保护你的牙齿。（龋病学主要研究蛀牙的病理学成因）。
座落于爱荷华城的爱荷华大学（University of Iowa）牙医学院的副教授马歇尔（Teresa Marshall）提醒大家，不管使用哪种牙膏，记得千万不要在喝完酸性饮料后马上刷牙，因为此时牙釉质最容易遭到磨损。专家建议，食用或饮用酸性食物之后喝几口水是一种不错的办法，要不就嚼一片无糖口香糖，这有助于促进唾液分泌。
一项针对药房常见品牌牙膏的非正式调查发现，有些牙膏虽然号称可以加固牙釉质，成分却跟同品牌的其它牙膏几乎相同。据厂家介绍，其中的差别在于各种成分所占比例不同，具体的比例构成则受专利保护。
在专家看来，任何一支功效良好的含氟牙膏都能提高牙釉质的耐酸性。费瑟斯通说，牙膏包装上说的加固牙釉质不过是一个营销上的噱头。他已经为好几家牙膏厂商做过收费咨询。在他看来，消费者应该根据牙膏的口味来选择自己喜欢的品牌，这样才会经常刷牙。他推荐那些大品牌的牙膏，因为大量的研究能够确保配方的稳定和适当。
宝洁公司（Procter & Gamble）表示，公司旗下佳洁士“健康专家”系列中的“牙釉质防护盾”是公司逾十年研发的结晶，蕴含了七项独立研究的成果。该公司表示，产品包装上所说的“强化牙釉质”指的是从化学的角度提高牙齿的耐酸性。舒酸定的制造商葛兰素史克公司则认为，虽然氟化物并不能显著强化健康牙齿的牙釉质，但却可以对已遭受酸侵蚀的问题牙产生较好的强化效果。高露洁棕榄（Colgate-Palmolive）公司则拒绝接受采访。
至少有宝洁和葛兰素史克两家公司发布了相关研究，证实旗下产品确实有助于牙釉质的防护。试验对象或是那种佩戴了牙冠的假牙，或是那些含有试验用牙的特殊装置。（此类研究允许科学家开展对比测试，比如人为制造酸侵蚀环境以观察牙齿的耐酸性）。然而，科学家们说，直接比较两种牙膏的防护特性以确定哪种牙膏功效更佳，这样的试验并不多见。
根据成分的不同，牙膏之间也存在差异。据高露洁公司的网站介绍，全新的“临床专家”（ProClinical）系列中的Daily Renewal for Enamel牙膏在每一百万单位氟化物中含有1500单位的活性成份，这个比例高于绝大多数牙膏。 葛兰素史克公司则说，公司旗下的舒酸定牙膏配方较为独特，含有更多的氟化物，可以促进牙釉质的再矿化过程。科学家们说，额外添加的氟化物可能会对牙釉质产生一点细微的保护效果，不过，这也有赖于更多研究的证实。
此外，去年上市的佳洁士“牙釉质防护盾”添加了一种特殊的氟化物，名叫氟化亚锡（stannous fluoride）。据生化学家多伊尔（Matthew J. Doyle）介绍，氟化亚锡不仅能让氟磷灰石像其它氟化物一样结晶，还能杀死那些产生酸性物质的口腔细菌。多伊尔同时担任着宝洁公司口腔护理部的全球研发主任。多伊尔补充说，氟化亚锡同时也具有抗敏功效，因为它可以封闭那些通往牙神经的微细管道。
佳洁士的“牙釉质防护盾”还含有一种名为六聚偏磷酸钠（sodium hexametaphosphate）的成份，这种物质可以在牙齿表面形成一张保护性薄膜，持续有效的时间为六至七个小时。多伊尔博士说，它就像一个保护层，可以保护牙齿表面。
Laura Johannes
（本文版权归道琼斯公司所有，未经许可不得翻译或转载。）
http://www.cn.wsj.com/gb/20101124/hea083947.asp?source=UpFeature
Toothpaste makers are pitching enamel-strengthening toothpastes that they say harden the tooth's protective layer, making it more resistant to attacks from acids found in food and beverages such as soda, orange juice and even pickles. Scientists say the toothpastes do make enamel more acid-resistant -- but not enough to protect you if you guzzle soda all day.
Enamel is a thin covering over teeth made from an organic matrix and minerals, largely crystals of calcium phosphate, says scientist George Stookey, chief executive of Therametric Technologies Inc., a Noblesville, Ind., firm that sells and tests dental products. Enamel is vulnerable both to decay, caused by acids in bacteria, and to erosion, defined as direct assault from acids from food and drink, scientists say. The biggest culprits include diet and regular soda, citrus beverages, red wine and some sports drinks.
Everyone is vulnerable to acid erosion, but as we age the problem worsens with a decrease in production of saliva -- which both washes away acids and neutralizes them. Some medications also decrease saliva production.
A number of toothpastes that claim to combat acid erosion and strengthen enamel are now on the market. Crest Pro-Health Enamel Shield's label says it 'protects against acid attack.' Sensodyne ProNamel says it 'protects against the effects of acid erosion.' Colgate Total's line includes an 'Enamel Strength' version. A CVS store brand promises it 'helps harden tooth enamel with acid protection formula.'
The claims are often based on the presence of fluoride, which scientists say combines with minerals in your mouth to create a crystal called fluorapatite on the surface of your teeth. Some of the toothpastes, including Crest's Enamel Shield, Sensodyne ProNamel and Squigle Inc.'s Enamel Saver, are also formulated to be less abrasive to protect your enamel from rubbing off when brushing. (Squigle is a manufacturer of a small brand of toothpastes it says are non-irritating to the mouth.)
Scientists give mixed reviews to the claims. They say it is incorrect to say a toothpaste can strengthen enamel as it doesn't make teeth physically stronger against shearing forces -- such as biting into a piece of popcorn. The products do make the tooth surface more resistant to acids in the diet, says John Featherstone, dean of the University of California School of Dentistry in San Francisco.
While dentists agree toothpastes can help protect enamel, you should still drink acidic beverages in moderation. 'You can't drink erosive foods and drinks in high frequency and expect a toothpaste to protect you,' says Mark S. Wolff, a professor and chairman of the department of cariology and comprehensive care at New York University College of Dentistry. (Cariology is the study of tooth decay.)
Regardless of the toothpaste you use, it is important not to brush your teeth immediately after drinking acids as that is when enamel is most vulnerable to wear from brushing, adds Teresa Marshall, an associate professor at the University of Iowa College of Dentistry in Iowa City. It's a good idea to take a few sips of water after drinking or eating acids, scientists add, and sugar-free gum can help by stimulating saliva production.
As for toothpastes touting enamel strengthening, an informal inspection of labels in pharmacy aisles found the toothpastes often had nearly identical ingredients to other products by the same manufacturers that don't make enamel claims. Some of the distinction, companies say, involves proprietary differences in proportions of ingredients.
Scientists say any well-designed fluoride toothpaste will make enamel more acid resistant. The enamel-strengthening claims on the label are 'a marketing gimmick,' says Dr. Featherstone, who has done paid consulting for a number of toothpaste makers. Consumers should choose a toothpaste with a taste they like, as they'll use it more, he says. He recommends major brands because a lot of research goes into proper formulation.
Procter & Gamble says its Crest Pro-Health Enamel Shield is the result of more than a decade of research and seven separate inventions. The company says the term 'strengthens enamel' on the label refers to making teeth more chemically resistant to acid. GlaxoSmithKline, maker of Sensodyne ProNamel, says that, while fluoride doesn't significantly harden normal tooth enamel it does have a hardening effect on enamel which has been softened by acid erosion. Colgate-Palmolive declined to be interviewed.
At least two companies -- P&G and GlaxoSmithKline -- have published studies showing their toothpastes help protect enamel in test subjects wearing either crowns or appliances with test teeth in them. (This type of research allows scientists to perform controlled tests, such as deliberately creating acid erosion on the test teeth.) However, there aren't enough well-designed studies directly comparing one toothpaste with another to determine if one toothpaste is really better than another, scientists say.
Based on ingredients, there are some differentiation points. Colgate's new ProClinical Daily Renewal for Enamel, has 1,500 parts per million of fluoride -- more than most toothpastes, according to the company's website. Sensodyne ProNamel is specially formulated so that more fluoride is available, enhancing the process of remineralizing enamel, GlaxoSmithKline says. Scientists say extra fluoride is likely to have at least a small additional effect on enamel -- but more research is needed.
P&G's Crest Pro-Health Enamel Shield, which came out last year, is made with a particular type of fluoride called stannous fluoride. In addition to forming fluorapatite crystals like other fluorides, stannous fluoride also has a toxic effect on acid-producing mouth bacteria, says biochemist Matthew J. Doyle, director of global research and development for P&G's oral-care division. Stannous fluoride also protects against tooth sensitivity by blocking small tunnels in the teeth, he adds.
Crest's Pro-Health Enamel Shield also has sodium hexametaphosphate, an ingredient that forms a protective film over the teeth that lasts six or seven hours. 'It's a sacrificial layer that protects the surface of the tooth,' Dr. Doyle says.
Laura Johannes
Enamel is a thin covering over teeth made from an organic matrix and minerals, largely crystals of calcium phosphate, says scientist George Stookey, chief executive of Therametric Technologies Inc., a Noblesville, Ind., firm that sells and tests dental products. Enamel is vulnerable both to decay, caused by acids in bacteria, and to erosion, defined as direct assault from acids from food and drink, scientists say. The biggest culprits include diet and regular soda, citrus beverages, red wine and some sports drinks.
Everyone is vulnerable to acid erosion, but as we age the problem worsens with a decrease in production of saliva -- which both washes away acids and neutralizes them. Some medications also decrease saliva production.
A number of toothpastes that claim to combat acid erosion and strengthen enamel are now on the market. Crest Pro-Health Enamel Shield's label says it 'protects against acid attack.' Sensodyne ProNamel says it 'protects against the effects of acid erosion.' Colgate Total's line includes an 'Enamel Strength' version. A CVS store brand promises it 'helps harden tooth enamel with acid protection formula.'
The claims are often based on the presence of fluoride, which scientists say combines with minerals in your mouth to create a crystal called fluorapatite on the surface of your teeth. Some of the toothpastes, including Crest's Enamel Shield, Sensodyne ProNamel and Squigle Inc.'s Enamel Saver, are also formulated to be less abrasive to protect your enamel from rubbing off when brushing. (Squigle is a manufacturer of a small brand of toothpastes it says are non-irritating to the mouth.)
Scientists give mixed reviews to the claims. They say it is incorrect to say a toothpaste can strengthen enamel as it doesn't make teeth physically stronger against shearing forces -- such as biting into a piece of popcorn. The products do make the tooth surface more resistant to acids in the diet, says John Featherstone, dean of the University of California School of Dentistry in San Francisco.
While dentists agree toothpastes can help protect enamel, you should still drink acidic beverages in moderation. 'You can't drink erosive foods and drinks in high frequency and expect a toothpaste to protect you,' says Mark S. Wolff, a professor and chairman of the department of cariology and comprehensive care at New York University College of Dentistry. (Cariology is the study of tooth decay.)
Regardless of the toothpaste you use, it is important not to brush your teeth immediately after drinking acids as that is when enamel is most vulnerable to wear from brushing, adds Teresa Marshall, an associate professor at the University of Iowa College of Dentistry in Iowa City. It's a good idea to take a few sips of water after drinking or eating acids, scientists add, and sugar-free gum can help by stimulating saliva production.
As for toothpastes touting enamel strengthening, an informal inspection of labels in pharmacy aisles found the toothpastes often had nearly identical ingredients to other products by the same manufacturers that don't make enamel claims. Some of the distinction, companies say, involves proprietary differences in proportions of ingredients.
Scientists say any well-designed fluoride toothpaste will make enamel more acid resistant. The enamel-strengthening claims on the label are 'a marketing gimmick,' says Dr. Featherstone, who has done paid consulting for a number of toothpaste makers. Consumers should choose a toothpaste with a taste they like, as they'll use it more, he says. He recommends major brands because a lot of research goes into proper formulation.
Procter & Gamble says its Crest Pro-Health Enamel Shield is the result of more than a decade of research and seven separate inventions. The company says the term 'strengthens enamel' on the label refers to making teeth more chemically resistant to acid. GlaxoSmithKline, maker of Sensodyne ProNamel, says that, while fluoride doesn't significantly harden normal tooth enamel it does have a hardening effect on enamel which has been softened by acid erosion. Colgate-Palmolive declined to be interviewed.
At least two companies -- P&G and GlaxoSmithKline -- have published studies showing their toothpastes help protect enamel in test subjects wearing either crowns or appliances with test teeth in them. (This type of research allows scientists to perform controlled tests, such as deliberately creating acid erosion on the test teeth.) However, there aren't enough well-designed studies directly comparing one toothpaste with another to determine if one toothpaste is really better than another, scientists say.
Based on ingredients, there are some differentiation points. Colgate's new ProClinical Daily Renewal for Enamel, has 1,500 parts per million of fluoride -- more than most toothpastes, according to the company's website. Sensodyne ProNamel is specially formulated so that more fluoride is available, enhancing the process of remineralizing enamel, GlaxoSmithKline says. Scientists say extra fluoride is likely to have at least a small additional effect on enamel -- but more research is needed.
P&G's Crest Pro-Health Enamel Shield, which came out last year, is made with a particular type of fluoride called stannous fluoride. In addition to forming fluorapatite crystals like other fluorides, stannous fluoride also has a toxic effect on acid-producing mouth bacteria, says biochemist Matthew J. Doyle, director of global research and development for P&G's oral-care division. Stannous fluoride also protects against tooth sensitivity by blocking small tunnels in the teeth, he adds.
Crest's Pro-Health Enamel Shield also has sodium hexametaphosphate, an ingredient that forms a protective film over the teeth that lasts six or seven hours. 'It's a sacrificial layer that protects the surface of the tooth,' Dr. Doyle says.
Laura Johannes
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