It is not necessary to mill the surface of the tooth and the crystal is bonded onto the surface of the desired tooth by your dentist using special adhesive.
Does tooth crystal fall off in time?
Since it is bonded onto the tooth surface, it may fall off if it is excessively forced by biting maneuvers; however your tooth will not be damaged if it falls off. It can be bonded again if it falls off.
How is tooth diamond bonded?
The tooth diamond is a natural gem and the bonded surface is sharp. To fit this sharp surface to the tooth, the surface of tooth is slightly milled in the diameter of sharp end of the diamond. A special adhesive is applied between the tooth and the diamond.