Today brought the joys of dentistry, not to mention the joys of the Cavitron apparatus, yet another tool of the devil. Luckily there was some trouble with it, so yours truly was not subjected to its ministrations until nearly the end of the session. The noise is at an extremely unpleasant frequency, and the feeling is not to great, either. It appears that those wearing pacemakers should not be subjected to ultrasonic scaling, as the frequency interferes with pacemaker function.