BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 5767978 · Received July 4, 2016

    Report

    Report Number
    9611253-2016-00033
    Event Type
    Injury
    Date Received
    July 4, 2016
    Date of Event
    June 8, 2016
    Report Date
    December 6, 2016
    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

    AS OF JULY 1, 2016, NAKANISHI HAS RECEIVED LIMITED INFORMATION ABOUT THE EVENT, THEREFORE NAKANISHI IS SCHEDULED TO VISIT THE DENTIST FOR MORE INFORMATION INCLUDING THE PATIENT INFORMATION NEXT WEEK.

    Additional Manufacturer Narrative · 1

    ON (B)(6) 2016, NAKANISHI VISITED THE DENTIST FOR INFORMATION ABOUT THE PATIENT. HOWEVER, NAKANISHI COULD NOT OBTAIN ANY INFORMATION FROM THE DENTIST. UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM A DISTRIBUTOR, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE THAT INCLUDED MEASURING THE TEMPERATURE OF THE OPERATING DEVICE [C160608-19-1]. 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 (B)(4)]. THERE WERE NO PROBLEMS OBSERVED DURING THE MANUFACTURING OR TESTING NOTED IN THE DHR. THE REPAIR HISTORY SHOWED 2 SERVICE RECORDS (FEBRUARY 2015 AND APRIL 2015) 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 A 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 SITUATION. 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 ABNORMAL RISES IN TEMPERATURE AT TEST POINTS (1) AND (2) 30 SECONDS AFTER THE START. TEMPERATURE MEASUREMENTS 30 SECONDS AFTER THE START ARE AS FOLLOWS: - TEST POINT (1): 59.3 DEGREES C. - TEST POINT (2): 72.8 DEGREES C. - TEST POINT (3): 29.0 DEGREES C. - TEST POINT (4): 28.7 DEGREES C. BECAUSE THE TEMPERATURE RISE WAS SO SUDDEN AT POINTS (1) AND (2), THE TEST WAS CONDUCTED FOR ONLY 30 SECONDS INTO THE PLANNED 2 MINUTE EVALUATION PERIOD. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS INVOLVED: A) NAKANISHI CHECKED THE SPRAY CONDITIONS AND WATER SUPPLY AMOUNTS OF THE DEVICE AND CONFIRMED THAT BOTH THE CONDITIONS AND THE WATER AMOUNTS WERE NORMAL. - WATER SUPPLY AMOUNTS MEASURED IN THIS INSPECTION : 38ML/MIN (NAKANISHI STANDARD : 37ML/MIN OR GREATER UNDER 0.1MPA (WATER PRESSURE)/0.15MPA UNDER 0.15MPA (CHIP AIR PRESSURE)). B) NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED THE FOLLOWING PHENOMENA: - A PART OF THE BEARING RETAINER (BALL RETAINING PLASTIC PART) OF THE BALL BEARING ON THE CARTRIDGE'S REAR SIDE (PUSH BUTTON SIDE) WAS BROKEN. - THERE WAS DIRT (ABRASIVE POWDERS) INSIDE THE HEAD CAP PUSH BUTTON. C) NAKANISHI TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS 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 FRICTIONAL RESISTANCE GENERATED BY CONTACT BETWEEN THE BALL BEARING PART AND THE OUTER RACE (BEARING OUTER METAL PART), WHICH WAS GENERATED BY CENTRIFUGAL ACTION DURING ROTATION DUE TO THE BROKEN BALL BEARING PART. 2) NAKANISHI CONSIDERS THE POSSIBILITY FROM MANY YEARS OF EXPERIENCE THAT THE CAUSE OF THE BALL BEARING PART BEING BROKEN WAS THE INGRESS OF DIRT (ABRASIVE POWDERS) INTO THE BALL BEARING THAT INTERFERED WITH ROTATION, WHICH LEAD TO THE BREAKAGE OF THE BALL BEARING PART. 3) A LACK OF MAINTENANCE CAUSES THE ABOVE SITUATION, WHICH WILL CONTRIBUTE TO THE HANDPIECE OVERHEATING. 4) NAKANISHI TOOK THE FOLLOWING ACTIONS IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING. 4.1) NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. 4.2) NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO THE DENTIST AND REMINDED THE DENTIST OF THE IMPORTANCE OF MAINTENANCE AND CHECKING OF THE HANDPIECE PRIOR TO USE TO PREVENT OVERHEATING, AS INSTRUCTED IN THE OPERATION MANUAL.

    Description of Event or Problem · 1

    ON (B)(6) 2016, NAKANISHI RECEIVED A PHONE CALL FROM A DISTRIBUTOR ABOUT HANDPIECE OVERHEATING. DETAILS ARE AS FOLLOWS. THE EVENT OCCURRED ON (B)(6) 2016. A DENTIST WAS PERFORMING A DENTAL PROCEDURE USING AN NSK HANDPIECE X95L (SERIAL NO. (B)(4)). DURING THE PROCEDURE, THE PATIENT SUFFERED A BURN.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    421897 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. X95L

    Patients

    Seq Age Sex Outcome Treatment
    1 Other