The labio-dental sounds are articulated by the lower lip against the upper teeth, eg. /f/.

唇齿音由下唇与上齿连接发出，例如 /f/。

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One of my upper teeth is loose and ached.

我的一颗上牙齿感到疼痛。

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One of my upper teeth is loose and aching.

我的一颗上齿松动而且疼痛。

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Doctors removed some of President Cleveland's teeth and much of his upper left jaw.

VOA: special.2010.06.24

"One of the ways you can tell that is how your upper teeth fit to the lower teeth, " Papay said.

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Sinusitis is inflammation of the nasal cavity and the sinuses, which are air-filled spaces located primarily in the jaw above the upper teeth and in the forehead around the eyes.

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The exact cause of teeth grinding is not known, but the most likely culprits are things like stress, sleep disorders, crooked or missing teeth and having an abnormal bite, where the upper and lower teeth do not come together normally (known as malocclusion).

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