Only hard tartar is removed with sharp instruments, soft plaque is cleaned with brushes and rubbers with a special paste. In addition, the tooth enamel is very hard, so it is difficult to damage it even using sharp metal instruments.
In our Clinic, hard tartar is removed using an ultrasonic scaler, i.e. vibration caused by ultrasonic waves remove tartar. A tip of the scaler is not sharp at all, and does not cause damage to the enamel of the tooth.