A few months ago, Boston Scientific, one of the major manufacturers of pacemakers/ICDs, added a new caution to their contraindications for dental patients. They warn that if a patient has a pacemaker/ICD, and the dental chair has a magnetic headrest with strength over 10 gauss, the patient should NOT sit in the chair.The linked article above does a good job giving a balanced review of this topic, so take a minute to read the whole thing.
The company states: “Some dental chairs contain magnets located in the headrest. If the pacemaker or defibrillator is programmed not to respond to a magnet, patients may sit in these chairs. If the implanted device is programmed to respond to a magnet and the magnet power is less than 10 gauss, patients may sit in these chairs. If the magnet power is greater than or equal to 10 gauss, patients should not sit in these chairs as the device function/programming may be affected.”
Allow me to explain. Magnet strength is measured in gauss units. The farther the distance from the magnet, the weaker the gauss reading, which means a weaker magnetic field. The magnets on dental chairs currently in use contain magnets with strength over 400 gauss. (Strengths vary slightly among manufacturers.) Therefore, sitting in the typical dental chair with a pacemaker/ICD, one would have to be five to six inches away from the magnet to be safe. Sometimes, however, dental professionals have trouble accessing certain parts of the mouth, and we ask patients to move up in the headrest, which is closer to the magnet. When we get too close to the magnet, the magnetic effect increases, and therefore, so does the potential for complications.
Reference: Boston Scientific's "Dental Equipment and Implantable Pacemakers and Defibrillators" white paper dated 2 Feb 2009.