Sir, I wonder if I could be permitted to reply to the letter by Dr Balfry (BDJ; 199: 625). I am a practising dentist and had a digital pacemaker fitted two years ago. I have regularly used an ultrasonic scaler in my practice without any problems. My pacemaker advice manual advises that 'dental drills, ultrasonic probes to clean teeth, and dental x-rays do not interfere with your pacemaker'. This presumes the pacemaker is used and maintained properly.