It accumulates negative ions in the atmosphere to blast out 10000- volt lightning bolts.
Teeth grinding is harmful for several reasons. First, it causes damage to the teeth by wearing the enamel off the biting surface of the tooth and along the gumline. This can lead to tooth sensitivity. Second, the forces generated from grinding can cause cracks to form in the teeth and can cause the teeth to break.
In the past, grinding (sideways movements of the jaws, with the teeth just touching) and clenching (clamping the uppers and lowers together) were believed to be caused by malocclusion (a bad bite).