BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 8538119 · Received April 22, 2019

    Report

    Report Number
    9611253-2019-00029
    Event Type
    Injury
    Date Received
    April 22, 2019
    Date of Event
    March 1, 2019
    Report Date
    June 6, 2019
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    NC, US
    Reporter Occupation
    OTHER HEALTH CARE PROFESSIONAL

    Narratives

    Additional Manufacturer Narrative · 0

    EXEMPTION NUMBER E2016004. (B)(4). (B)(4) TOOK THE FOLLOWING ACTIONS, BUT FURTHER INFORMATION ABOUT THE EVENT WAS STILL NOT PROVIDED. ON MARCH 28, 2019, (B)(4) RECEIVED AN (B)(4) X95L HANDPIECE FOR REPAIR WITH A NOTE STATING THAT THE DEVICE HAD OVERHEATED AND BURNED A PATIENT. ON APRIL 1, 2019, (B)(4) MADE A PHONE CALL TO THE DENTAL OFFICE TO OBTAIN THE DETAILS. SINCE THE PERSON IN CHARGE WAS NOT AVAILABLE, (B)(4) LEFT A MESSAGE FOR THE PERSON IN CHARGE TO RETURN THE CALL. ON APRIL 2, 2019, (B)(4) RECEIVED A PHONE CALL FROM THE PERSON IN CHARGE, BUT THAT PERSON DID NOT HAVE THE DETAILS OF THE EVENT AT THE TIME OF THE CALL. THE PERSON IN CHARGE PROVIDED AN E-MAIL ADDRESS TO ALLOW (B)(4) TO REQUEST FURTHER INFORMATION ABOUT THE EVENT. (B)(4) SENT AN E-MAIL REQUESTING THE INFORMATION. NO RESPONSE WAS RECEIVED. ON APRIL 15, 2019, (B)(4) SENT A FOLLOW UP E-MAIL FOR THE INFORMATION. (B)(4) IS STILL WAITING FOR THE DENTAL PRACTICE TO PROVIDE THE INFORMATION.

    Additional Manufacturer Narrative · 0

    NAKANISHI RECEIVED THE PATIENT INFORMATION FROM THE DISTRIBUTOR (NAM), BUT ACCORDING TO NAM, THE DENTIST REFUSED TO PROVIDE THE PATIENT WEIGHT. UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM THE DISTRIBUTOR, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE THAT INCLUDED MEASURING THE OPERATING TEMPERATURE OF THE DEVICE [C190405-04]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: A) NAKANISHI EXAMINED THE DEVICE HISTORY RECORD AND THE REPAIR HISTORY FOR THE SUBJECT X95L DEVICE [SERIAL NUMBER EBGZ0258]. THERE WERE NO PROBLEMS OBSERVED DURING MANUFACTURING OR TESTING NOTED IN THE DHR. THERE WERE ALSO NO REPAIR HISTORY RECORDS SINCE THE DEVICE WAS SHIPPED. B) NAKANISHI CONDUCTED TEMPERATURE TESTING OF THE RETURNED DEVICE IN THE FOLLOWING MANNER: B.1) TEMPERATURE SENSORS WERE ATTACHED TO THE EXTERIOR OF THE DEVICE AT VARIOUS TEST POINTS. THIS INCLUDED THE POINT MOST PROXIMAL TO THE PATIENT (TESTING POINT (1)) AND POINTS FURTHER TOWARD THE DISTAL END OF THE DEVICE (TESTING POINTS (2) THROUGH (4)). 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 TEMPERATURE) TO EACH OF THE TESTING POINTS. NAKANISHI ROTATED THE DEVICE'S MOTOR AT 40,000 MIN-1, WHICH IS THE MAXIMUM RPM FOR THE MOTOR THAT DRIVES THE HANDPIECE (200,000 MIN-1 FOR THE HANDPIECE), WITH WATER SPRAY, AND MEASURED THE EXOTHERMIC RESPONSE. B.3) NAKANISHI MEASURED THE TEMPERATURE RISE OF THE RETURNED HANDPIECE SET AT 200,000 MIN-1 (MOTOR REVOLUTION 40,000 MIN-1). NAKANISHI OBSERVED AN ABNORMAL TEMPERATURE RISE AT TEST POINT (2) A FEW SECONDS AFTER THE START. TEMPERATURE MEASUREMENTS 26 SECONDS AFTER THE START ARE AS FOLLOWS: - TEST POINT (1): 44.1 DEGREES C - TEST POINT (2): 59.3 DEGREES C - TEST POINT (3): 24.8 DEGREES C - TEST POINT (4): 24.2 DEGREES C IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS INVOLVED: A) NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED THE FOLLOWING PHENOMENA: - THE BEARING RETAINER (BALL RETAINING PART) ON THE REAR SIDE OF THE CARTRIDGE WAS BROKEN. - THE DOG CLUTCH AND DRIVE SHAFT WERE PARTIALLY CORRODED. B) NAKANISHI TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS AND KEPT THEM IN THE INVESTIGATION REPORT #C190405-04. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: 1) NAKANISHI IDENTIFIED THAT THE CAUSE OF THE OVERHEATING OF THE RETURNED DEVICE WAS ABNORMAL RESISTANCE DURING ROTATION CAUSED BY THE BROKEN BEARING. 2) NAKANISHI CONSIDERS THE POSSIBILITY FROM MANY YEARS OF EXPERIENCE THAT THE CAUSE OF THE BALL BEARING BEING BROKEN WAS INGRESS OF FOREIGN MATERIALS INTO THE BALL BEARING LEADING TO ABRASION, WHICH RESULTS IN BREAKAGE OF THE BEARING. 3) A LACK OF MAINTENANCE CAUSES THE ABOVE SITUATION, WHICH CONTRIBUTES TO THE HANDPIECE OVERHEATING. 4) IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI TOOK THE FOLLOWING ACTIONS: 4.1) NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED THE CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. 4.2) 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.

    Description of Event or Problem · 0

    ON APRIL 5, 2019, NAKANISHI RECEIVED AN E-MAIL FROM A DISTRIBUTOR ((B)(4)) ABOUT A HANDPIECE OVERHEATING. DETAILS ARE AS FOLLOWS. THE EVENT OCCURRED AROUND (B)(6) 2019 (THE EXACT DATE IS UNKNOWN). A DENTIST WAS PERFORMING A DENTAL PROCEDURE USING THE X95L HANDPIECE (SERIAL NO. (B)(4)). DURING THE PROCEDURE, THE HANDPIECE OVERHEATED AND BURNED A PATIENT.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    331346 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. X95L

    Patients

    Seq Age Sex Outcome Treatment
    1 68 YR Other