台Taivo A Taiwan Mandarin dictionary

洗牙

xǐyá

ㄒㄧˇ ㄧㄚˊ

1(dentistry) to perform or undergo scaling (removal of dental plaque and calculus)

Example

你該去洗牙了。

nǐ gāi qù xǐyá le

You should go and brush your teeth.

Keep 洗牙 and it comes back until you know it.