BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 4992130 · Received August 10, 2015

    Report

    Report Number
    9611253-2015-00103
    Event Type
    Injury
    Date Received
    August 10, 2015
    Date of Event
    July 16, 2015
    Report Date
    October 23, 2015
    Manufacturer
    NAKANISHI, INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    JA
    Reporter Occupation
    OTHER

    Narratives

    Additional Manufacturer Narrative · 1

    UPON RECEIPT OF THE DEVICE INVOLVED IN THE MDR EVENT, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE THAT INCLUDED MEASUREMENT OF THE TEMPERATURE OF THE OPERATING DEVICE [C150730-04-1]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED : A) NAKANISHI EXAMINED THE DEVICE HISTORY RECORD FOR THE SUBJECT TI-MAX Z95L DEVICE [SERIAL NUMBER (B)(4)]. THERE WERE NO PROBLEMS OBSERVED DURING THE MANUFACTURING OR TESTING NOTED IN THE DHR. B) NAKANISHI CONDUCTED A TEMPERATURE TESTING OF THE RETURNED DEVICE IN THE FOLLOWING MANNER. B.1)TEMPERATURE SENSORS WERE FIRST ATTACHED TO THE EXTERIOR OF THE DEVICE AT VARIOUS TEST POINTS (E.G., MOST PROXIMAL TO THE PATIENT AND ALONG POINTS FURTHER TOWARD THE DISTAL END OF THE DEVICE). THE TEST SETUP WAS PREPARED TO TAKE TEMPERATURE MEASUREMENTS AT ALL POINTS SIMULTANEOUSLY, INCLUDING A REFERENCE MEASUREMENT AT AMBIENT ROOM TEMPERATURE. B.2) NAKANISHI ATTACHED A THERMOCOUPLE (SENSOR TO MEASURE A TEMPERATURE) TO EACH OF THE TESTING POINTS (1), (2), (3) AND (4). NAKANISHI ROTATED THE HANDPIECE AT 40,000 RPM, WHICH IS MAXIMUM RPM FOR THE MOTOR THAT DRIVES THE HANDPIECE (200,000 PRM FOR THE HANDPIECE), WITH WATER SPRAY AND MEASURED THE EXOTHERMIC SITUATION. B.3) NAKANISHI MEASURED THE TEMPERATURE RISE OF THE RETURNED HANDPIECE SET AT 200,000 RPM (MOTOR REVOLUTION 40,000RPM). NAKANISHI CONFIRMED THE ABNORMAL TEMPERATURE RISE AT THE TEST POINTS (1) AND (2) (POINTS CLOSE TO THE PATIENT) AS FOLLOWS AFTER THE BEGINNING OF THE MEASUREMENT ; (1) 52.6 DEGREES C AND (2) 67.2 DEGREES C. THE RISE WAS SO SUDDEN THAT THE TEMPERATURES, 52.6 DEGREES C AND 67.2 DEGREES C WERE OBSERVED ONLY ABOUT 30 SECONDS INTO THE PLANNED 5 MINUTES EVALUATION PERIOD. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENT(S) INVOLVED : A) NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED BREAKAGE OF THE RETAINER (A BALL RETAINING PART) IN THE CARTRIDGE BEARING. BALL POCKETS OF THE RETAINER WERE ALSO WORN. B) NAKANISHI TOOK PHOTOGRAPHS OF ALL THE DAMAGED PARTS MENTIONED ABOVE AND KEPT THEM IN A FILE. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS : 1) NAKANISHI IDENTIFIED THAT THE CAUSE OF OVERHEATING OF THE RETURNED DEVICE WAS DUE TO DAMAGE TO THE RETAINER. 2) NAKANISHI ALSO BELIEVES FROM MANY YEARS OF EXPERIENCE THAT THE CAUSE OF THE INNER PARTS DAMAGE IS DUE TO AGING DETERIORATION AS WELL AS DIRT/DEBRIS INGRESS INTO THE BEARING WHILE ROTATING, WHICH INTERFERES WITH THE ROTATION. 3) A LACK OF MAINTENANCE CAUSES THE PHENOMENON DESCRIBED IN THE ABOVE 1) AND 2), WHICH MAY RESULT IN ABNORMAL ROTATION RESISTANCE. THIS WILL CONTRIBUTE TO THE HANDPIECE OVERHEATING. 4) IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO THE DENTIST AND REMINDED THE DENTIST OF THE IMPORTANCE OF MAINTENANCE AND PRIOR-TO-USE CHECKUPS AS INSTRUCTED IN THE OPERATION MANUAL. ON (B)(4) 2015, NAKANISHI VISITED THE DENTAL CLINIC FOR MORE INFORMATION ABOUT THE EVENT. NAKANISHI OBTAINED THE PATIENT INFORMATION AS DESCRIBED, HOWEVER, THE DENTIST REFUSED TO DISCLOSE THE PATIENT'S WEIGHT. NAKANISHI ALSO FOUND OUT THAT THE BURNED AREA WAS NOT THE PATIENT'S LIP, IT WAS THE RIGHT CORNER OF THE MOUTH.

    Description of Event or Problem · 1

    ON (B)(6) 2015, NAKANISHI WAS AWARE OF THE POSSIBILITY OF A MDR REPORTABLE EVENT FROM THE INFORMATION ABOUT THE RETURNED PRODUCTS FOR REPAIR. NAKANISHI CONTACTED THE DISTRIBUTOR FOR A HEARING INVESTIGATION. DETAILS ARE AS FOLLOWS: ON (B)(6) 2015, A DENTIST BURNED A PATIENT ON THE LIP DUE TO OVERHEATING OF NSK HANDPIECE, TI-MAX Z95L; THE DENTIST WAS FORMING AN ANCHOR TOOTH WHEN THE EVENT OCCURRED; BEFORE FORMING THE ANCHOR TOOTH, THE DOCTOR WAS REMOVING A CROWN FROM THE PATIENT USING THE Z95L; CUMULATIVE OPERATIONAL TIME WAS ABOUT 20 MINUTES (15 MINUTES FOR CROWN REMOVAL AND ANCHOR TOOTH FORMATION FOR 5-6 MINUTES).

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    522168 NSK EGS NAKANISHI, INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 53 YR Other