BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 7002547 · Received November 6, 2017

    Report

    Report Number
    9611253-2017-00060
    Event Type
    Injury
    Date Received
    November 6, 2017
    Date of Event
    October 1, 2017
    Report Date
    November 21, 2017
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    JA
    Reporter Occupation
    OTHER

    Narratives

    Additional Manufacturer Narrative · 1

    WHEN (B)(6) CONTACTED THE DEALER ON (B)(6) 2017, THE DEALER DID NOT HAVE ANY INFORMATION ABOUT THE PATIENT. (B)(6) IS SCHEDULED TO GET IN TOUCH WITH THE DEALER AGAIN FOR THE PATIENT INFORMATION ANYTIME SOON.

    Additional Manufacturer Narrative · 1

    ON (B)(6) 2017, NAKANISHI MADE A PHONE CALL TO THE DENTIST FOR INFORMATION ABOUT THE PATIENT, BUT THE DENTIST REFUSED TO DISCLOSE THE INFORMATION. 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 OPERATING TEMPERATURE OF THE DEVICE [C171010-09]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: NAKANISHI EXAMINED THE DEVICE HISTORY RECORD AND THE REPAIR HISTORY FOR THE SUBJECT X95 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 (MARCH 2016 AND JULY 2016) SINCE THE DEVICE WAS SHIPPED. ACCORDING TO THE SERVICE RECORDS, AFTER REPAIRING THE HANDPIECE (REPLACEMENT OF CARTRIDGE, DRIVE SHAFT AND DOG CLUTCH FOR BOTH OF THE REPAIRS), NAKANISHI PERFORMED ALL OF THE NECESSARY OPERATION CHECKS AND CONFIRMED THAT ALL OF THE CRITERIA WERE MET. NAKANISHI CONDUCTED TEMPERATURE TESTING OF THE RETURNED DEVICE IN THE FOLLOWING MANNER: 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. 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 RESPONSE. 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) DURING THE 300-SECOND-TEST PERIOD. THE TEMPERATURE OBSERVED IN THE TEST PERIOD ARE AS FOLLOWS: TEST POINT (1): 39.4 DEGREES C. TEST POINT (2): 51.3 DEGREES C. TEST POINT (3): 36.4 DEGREES C. TEST POINT (4): 29.2 DEGREES C. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS INVOLVED: 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 CARTRIDGE REAR SIDE WAS ABRADED. THERE WAS ABRASION AND DEBRIS ON THE BEARING RACEWAY SURFACE (BALL ROLLING SURFACE). NAKANISHI TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS AND KEPT THEM IN THE INVESTIGATION REPORT # (B)(4). CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: NAKANISHI IDENTIFIED THAT THE CAUSE OF THE OVERHEATING OF THE RETURNED DEVICE WAS ABNORMAL RESISTANCE DURING ROTATION CAUSED BY THE ABRADED BEARING DUE TO THE INGRESS OF UNDESIRABLE MATERIALS INTO THE BEARING. A LACK OF MAINTENANCE CAUSES THE ACCUMULATION OF DEBRIS ON THE INSIDE PARTS, WHICH CAUSES DEBRIS INGRESS INTO THE BEARING DURING ROTATION. THIS CONTRIBUTES TO THE HANDPIECE OVERHEATING. IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI TOOK THE FOLLOWING ACTIONS: NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO THE DENTIST AND REMINDED THE DENTIST OF THE IMPORTANCE OF MAINTENANCE, AS INSTRUCTED IN THE OPERATION MANUAL.

    Description of Event or Problem · 1

    ON (B)(6) 2017, AN NSK HANDPIECE X95L WAS RETURNED FROM A DISTRIBUTOR TO NAKANISHI FOR REPAIR. THERE WAS A NOTE WITH THE DEVICE STATING THE DEVICE OVERHEATING. THE DETAILS ARE AS FOLLOWS. THE EVENT OCCURRED ON (B)(6) 2017. A DENTIST WAS REMOVING A CROWN FROM THE TOOTH (#5) OF THE PATIENT'S UPPER RIGHT JAW USING THE X95L HANDPIECE (SERIAL NO.: (B)(4)). THE PATIENT WAS NOT UNDER ANESTHESIA. DURING THE PROCEDURE, THE PATIENT COMPLAINED ABOUT PAIN IN THE PATIENT'S MOUTH. THE DENTIST FOUND A ONE-CENTIMETER BURN INJURY IN THE MOUTH.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    783470 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. X95

    Patients

    Seq Age Sex Outcome Treatment
    1 Other