BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 6407853 · Received March 15, 2017

    Report

    Report Number
    9611253-2017-00013
    Event Type
    Injury
    Date Received
    March 15, 2017
    Date of Event
    January 14, 2017
    Report Date
    June 6, 2017
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    CA
    Reporter Occupation
    OTHER

    Narratives

    Additional Manufacturer Narrative · 0

    (B)(4) TRIED TO OBTAIN ADDITIONAL INFORMATION ON THE EVENT FEBRUARY 23, 2017, BUT THE DEALER REFUSED TO PROVIDE ANY INFORMATION. UPON RECEIPT OF THE REPAIR REQUEST CONTAINING THE INFORMATION ON PATIENT INVOLVEMENT IN THE EVENT, (B)(4) TRIED TO OBTAIN THE ADDITIONAL INFORMATION AGAIN, INCLUDING THE PATIENT INFORMATION ON FEBRUARY 28, 2017, BUT THE DEALER REFUSED TO PROVIDE ANY INFORMATION. EXEMPTION NUMBER E2016004. - NAKANISHI INC. (MANUFACTURER) IS SUBMITTING THIS REPORT ON BEHALF OF (B)(4). (B)(4) IS LISTED HERE AND MR. (B)(4) BECAUSE MR. (B)(4) IS THE OFFICIAL CORRESPONDENT OF BOTH NAKANISHI INC. AND (B)(4).

    Description of Event or Problem · 0

    ON (B)(6) 2017, NAKANISHI RECEIVED AN EMAIL FROM A DISTRIBUTOR ((B)(4)) THAT STATES A HANDPIECE HAD OVERHEATED AND BURNED A PATIENT. DETAILS ARE AS FOLLOWS. 1) ON (B)(6) 2017, (B)(4) WAS INFORMED BY THE (B)(4) NSK SALES REPRESENTATIVE THAT A DEALER CONTACTED THE (B)(4) NSK SALES REPRESENTATIVE STATING A HANDPIECE WAS REPORTED TO HAVE OVERHEATED. 2) ON (B)(6) 2017, (B)(4) WAS MADE AWARE BY THE INCOMING REPAIR PAPERWORK FOR HANDPIECE MODEL Z95L (SERIAL NUMBER (B)(4)) THAT THE HANDPIECE HAD BECOME HOT AND BURNED A PATIENT'S CHEEK ON (B)(6) 2017. - A SERVICE HISTORY RECORD REVIEW WAS CONDUCTED BY THE SERIAL NUMBER, AND IT WAS DISCOVERED THAT THE HANDPIECE HAD NOT BEEN SERVICED BY NSK AMERICA.

    Additional Manufacturer Narrative · 1

    METHODOLOGY USED: A) NAKANISHI EXAMINED THE DEVICE HISTORY RECORD FOR THE SUBJECT Z95L DEVICE (SERIAL NUMBER BBF30043). THERE WERE NO PROBLEMS OBSERVED DURING THE MANUFACTURING OR TESTING NOTED IN THE DHR. B) NAKANISHI CONDUCTED A VISUAL INSPECTION OF THE RETURNED DEVICE AND PERFORMED A SIMPLE MOVEMENT TEST. - NAKANISHI SET A TEST BUR IN THE HANDPIECE AND ROTATED IT BY HAND. NAKANISHI OBSERVED A ROTATIONAL RESISTANCE. - NAKANISHI DID NOT OBSERVE ANY DAMAGE ON THE EXTERIOR. C) INVESTIGATION OF OVERHEATING: C.1) TEMPERATURE SENSORS WERE FIRST ATTACHED TO THE EXTERIOR OF THE DEVICE AT VARIOUS TEST POINTS (I.E. MOST PROXIMAL TO THE PATIENT, TESTING POINT (1), AND ALONG POINTS FURTHER TOWARDS THE DISTAL END OF THE DEVICE, TESTING POINTS (2) THROUGH (4)). THE TEST WAS SET UP TO TAKE TEMPERATURE MEASUREMENTS AT ALL POINTS SIMULTANEOUSLY, INCLUDING A REFERENCE MEASUREMENT AT AMBIENT ROOM TEMPERATURE. C.2) NAKANISHI ATTACHED A THERMOCOUPLE (SENSOR TO MEASURE TEMPERATURE) TO EACH POINT. NAKANISHI ROTATED THE MOTOR AT 40,000 MIN-1, WHICH IS MAXIMUM RPM FOR THE MOTOR THAT DRIVES THE HANDPIECE (200,000 MIN-1 FOR THE HANDPIECE), WITH WATER SPRAY, AND MEASURED THE EXOTHERMIC SITUATION. C.3) NAKANISHI OBSERVED ABNORMAL TEMPERATURE RISES AT TEST POINTS (1) AND (2) 13 SECONDS AFTER THE START. TEMPERATURE MEASUREMENTS 13 SECONDS AFTER THE START ARE AS FOLLOWS: - TEST POINT (1): 59.1 DEGREES C - TEST POINT (2): 80.6 DEGREES C - TEST POINT (3): 29.3 DEGREES C - TEST POINT (4): 29.2 DEGREES C THE TEMPERATURE TESTING WAS CONDUCTED FOR 13 SECONDS INTO THE PLANNED 5 MINUTE EVALUATION. D) IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS INVOLVED: D.1) NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED FOUR CRACKS ON A BEARING RETAINER (BALL RETAINING PLASTIC PART). NAKANISHI THEN DISASSEMBLED THE BEARING AND OBSERVED ABRASION ON THE BALL POCKET. D.2) NAKANISHI CONFIRMED THAT THE OTHER PARTS WERE NORMAL. D.3) NAKANISHI TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS AND KEPT THEM IN A FILE. D.4) NAKANISHI THEN REPLACED THE CARTRIDGE CONTAINING THE BEARING AND MEASURED THE EXOTHERMIC SITUATION YET AGAIN. THERE WAS NO ABNORMAL TEMPERATURE RISE DURING THE TEST PERIOD. NAKANISHI CONFIRMED THAT THE RETURNED HANDPIECE WAS OPERATING AS EXPECTED AND WITHIN TEMPERATURE SPECIFICATION ONCE THE DAMAGED CARTRIDGE HAD BEEN REPLACED. E) CONCLUSION REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULT: E.1) NAKANISHI IDENTIFIED THAT THE CAUSE OF THE OVERHEATING OF THE RETURNED DEVICE WAS ABNORMAL RESISTANCE DURING ROTATION CAUSED BY THE DAMAGED BEARING. E.2) A LACK OF MAINTENANCE CAUSES THE ACCUMULATION OF DIRT (ABRASIVE POWDERS/FOREIGN MATERIALS) IN THE INSIDE PARTS, WHICH CAUSES DIRT/DEBRIS INGRESS INTO THE BEARING DURING ROTATION. THIS DAMAGES THE BEARING AND THEN CONTRIBUTES TO THE HANDPIECE OVERHEATING. E.3) IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI TOOK THE FOLLOWING ACTIONS: E.3.1) NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. E.3.2) NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO NSK AMERICA AND DIRECTED NSK AMERICA TO REMIND THE USER OF THE IMPORTANCE OF MAINTENANCE AS INSTRUCTED IN THE OPERATION MANUAL.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    190716 NSK HANDPIECE, CONTRA-AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 Other