The researchers demineralized the 180-million-year-old fossil of an ichthyosaur...and left behind soft, flexible tissues.

研究人员对1.8亿年前的鱼龙化石进行了去矿物质处理，留下柔软且有韧性的组织。

That environment favors bacteria like mutans streptococci and Lactobacillus, which demineralize enamel and the dentin beneath it, and if untreated, it can eventually result in a cavitated caries lesion.

酸性境下的优势菌例如变形链球菌和乳酸杆菌，可以食牙釉质及其下层的牙本质脱矿，如果不加以治疗，最终会形型龋齿。

So typically, dental plaque can form on the surface of teeth, b ut if the pH of the local environment around the tooth surface remains above about 5.5, enamel will not demineralize.

一般情况下，牙菌斑形于牙齿表面，但当牙表面局部境的pH值持续高于5.5时，牙釉质将不能脱矿化。