For instance, our anticavity toothpaste has expiration dating because over time, the fluoride becomes less available to your teeth.
比如说，我们的防龋齿牙膏有保质期，那是因为时间长了，里面氟的浓度就降低了。
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For instance, our anticavity toothpaste has expiration dating because over time, the fluoride becomes less available to your teeth. The products don't become harmful at any time, just less effective.