3M TRUE DEFINITION SCANNER

Additional Manufacturer Narrative

THE USERS MANUAL FOR THE 3M TRUE DEFINITION SCANNER SPECIFICALLY AND PROMINENTLY WARNS THE DENTAL PROFESSIONAL THAT A PROPERLY GROUNDED OUTLET MUST BE USED TO AVOID THE RISK OF ELECTRICAL SHOCK.

Description of Event or Problem

ON (B)(6) 2014 3M ESPE WAS INFORMED THAT A DENTIST EXPERIENCED THREE ELECTRICAL SHOCKS WHEN SCANNING A TYPODONT WITH THE 3M TRUE DEFINITION SCANNER. ONE OF THESE ELECTRICAL SHOCKS WAS INTENSE ENOUGH TO CAUSE THE DOCTOR TO DROP THE WAND. THE DOCTOR DID NOT REQUIRE MEDICAL ATTENTION AND IS FINE. TWO OTHER DENTISTS IN THE SAME OFFICE WERE TRYING OUT THE SCANNER AT THE SAME TIME AND DID NOT EXPERIENCE ANY ELECTRICAL SENSATION. IT WAS STATED THAT THE FIRST DOCTOR WAS THE ONLY DENTIST IN THE OFFICE WEARING WET, LEATHER-SOLED DRESS SHOES. DURING HIS FIRST SCANNING TRIAL HE WORE MEDICAL GLOVES AND DID NOT NOTICE AN ELECTRICAL SENSATION. SUBSEQUENT SCANS WERE DONE WITHOUT GLOVES, AND HE THEN NOTED THE ELECTRICAL SHOCKS. 3M ESPE ADVISED TO POWER OFF THE SCANNER AND REFRAIN FROM FURTHER USE UNTIL THE MATTER COULD BE INVESTIGATED. ON (B)(6) 2014, A 3M ESPE SERVICE SPECIALIST VISITED THE DENTAL OFFICE TO INVESTIGATE. THE SCANNER WAS CONNECTED TO THE SAME BANK OF WALL OUTLETS. TO THE BEST OF THE DENTAL ASSISTANT'S KNOWLEDGE, THE SCANNER WAS PLUGGED INTO EXACT SAME OUTLET IN THE BANK OF FOUR OUTLETS. ELECTRICAL MEASUREMENTS OF THE POWER CORD SHOWED IT PERFORMED NORMALLY. WHEN CHECKING THE WALL OUTLET, THE SERVICE SPECIALIST NOTED THE VOLTAGE BETWEEN THE GROUND AND NEUTRAL WAS APPROX. 60 V. IN A PROPERLY GROUNDED OUTLET, THIS VOLTAGE SHOULD BE ZERO. THE SAME VOLTAGE WAS MEASURED BETWEEN A COPPER WATER PIPE UNDER THE SINK AND THE OUTLET GROUND, CONFIRMING THAT THE OUTLET WAS NOT PROPERLY GROUNDED. SINCE THE METAL HOUSING OF THE SCANNER WANT IS CONNECTED TO THE GROUND, THIS SITUATION RESULTED IN AN ENERGIZED WANT (60V POTENTIAL). WHEN THE DOCTOR TOUCHED THE WANT WITH HIS BARE HANDS AND WET LEATHER-SOLED SHOES, HE MOST LIKELY COMPLETED A PATH TO REAL GROUND (0 V POTENTIAL) WHICH RESULTED IN THE ELECTRICAL SHOCK HE REPORTED. ON (B)(6) 2014, AN ELECTRICIAN CALLED BY THE DENTAL OFFICE READILY AGREED. A FOLLOW UP CALL BY 3M ESPE TO THE DENTAL OFFICE ON (B)(6) 2014, CONFIRMED THE DENTIST IS DOING FINE, THE ELECTRICIAN HAS CORRECTED THE WIRING IN THE AFFECTED OPERATORY, AND THE OFFICE HAS NOT HAD ANY FURTHER ISSUES WITH THE SCANNER . SINCE THE 3M TRUE DEFINITION SCANNER FUNCTIONED AS INTENDED, BUT INADEQUATE GROUND WIRING IN THE OFFICE RESULTED IN A DOCTOR RECEIVING AN ELECTRICAL SHOCK, THIS EVENT IS BEING REPORTED.