A dental cavity is a hole in the tooth 牙洞是牙齿上有一个洞
A cavity is caused by bacteria in the mouth 牙洞是嘴里的细菌引起的
Brushing your teeth frequently and regularly can help prevent cavities 定期有频次的刷牙能帮助预防蛀牙
A cracked tooth can be caused by biting down on something hard 牙齿破裂可能是由于用力咬东西引起的
Dentisits treat a cracked tooth by covering it with a crown 牙医用牙冠覆盖裂开的牙齿来治疗
A dental X-Ray is a picture of your teeth and gums 牙科的X光 是你牙齿和牙龈的照片
An X-Ray shows what can't be seen on the surface of the the teeth and gums x光片展示牙齿和牙龈表面不能被看到的
Braces are used by dentisits to straighten teeth over a period of years 牙医用牙套矫正牙齿 需要几年时间
Though braces are usually for children，they can also be used for adults with crooked teeth 虽然牙套通常为小孩使用，也能被成年人使用矫正牙齿
To extract a tooth，means to remove it from the mouth 拔牙，意思是从嘴里移除
Dentists have to pull hard to extract a tooth 牙医必须使劲拔牙
Dentisits often inject something into the gum to block the pain during the extraction process 在拔牙过程中，牙医通常注入一些东西到牙龈里来止痛
Braces are used on people with crooked teeth or after an injury 牙套被用于牙齿歪和牙齿受伤后的人
