The regular use of a bit to control a horse can create wear facets or bevels on the anterior corners of the lower second premolars. The corners of the horse's mouth normally keep the bit on the "bars" of the mouth, an interdental space where there are no teeth, forward of the premolars. The bit must be manipulated by a human or the horse must move it with its tongue for it to touch the teeth. Wear can be caused by the bit abrading the front corners of the premolars if the horse grasps and releases the bit between its teeth; other wear can be created by the bit striking the vertical front edge of the lower premolars, due to very strong pressure from a human handler.