Together, these differences prevent any light that may be in the deep water from reflecting off the tooth surface.

总的来说，这种与众不同的差异可以防止深水中的光线反射到牙齿表面。

That's where there's repeated physical trauma like rubbing of the tooth surface against the mucosa of the cheeks.

这是由于反复摩擦导致的物理损伤，如牙齿表面对颊黏膜的摩擦。

Saliva also contains calcium and phosphate, which serve as replacement minerals, to help remineralization of the tooth surface.

此外还有钙和磷酸盐，可以在牙齿表面再矿化的过程中，作为替代的矿物质。

For example, after a dental procedure that leaves a rough tooth surface, or a broken tooth rubbing against the mucosa.

比如，某次牙科治疗使牙齿变面变得粗糙，或者某颗坏掉的牙齿不断摩擦黏膜。

An advanced caries lesion can progress to a point where the tooth surface forms a cavitation or a hole, which is the physical evidence of tooth breakdown.

龋洞进一步发展会导致牙齿表面形成洞穴，是牙齿损坏的实证。

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，牙菌斑形成于牙齿表面，但当牙表面局部环境的pH值持续高于5.5时，牙釉质将不能脱矿化。