It is a proven fact that fluoride strengthens growing teeth.
氟化物可以强化生长中的牙齿，这是已证明的事实。
《牛津词典》
At this stage, the tooth can repair the weakened area with the help of fluoride and minerals in saliva.
在这个阶段，牙齿可以借助唾液中的氟化物和矿物质修复脆弱的部位。
A litre of teacan contain up to 9mg of fluoride, which in excess can cause skeletal fluorosis, reducing bone quality and causing pain and stiffening of the ligaments.
