Laboratory tests reveal it reacts with saliva to form a silica-hydroxyl layer on the ceramic that is softer, less abrasive, and gentler to opposing dentition than conventional porcelains.

实验室检测显示，这种瓷粉会与唾液反应在瓷层表面形成一个硅羟基层，这个硅羟基层更软，磨损度更小，与传统瓷粉相比对对颌牙更温和。

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The concept is not that fanciful: after all, fluid-coupling flywheel devices, where a confined liquid does the job normally done by two abrasive discs as in a conventional clutch, have been used in many vehicles, including traditional London buses.

ECONOMIST: An engine made of water