BEUDAMED
    FDA Adverse Event Malfunction Summary report: N

    NSK

    MDR report key: 7125308 · Received December 18, 2017

    Report

    Report Number
    9611253-2017-00066
    Event Type
    Malfunction
    Date Received
    December 18, 2017
    Date of Event
    December 1, 2017
    Report Date
    January 11, 2018
    Manufacturer
    NAKANISHI INC
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    JA
    Reporter Occupation
    OTHER

    Narratives

    Additional Manufacturer Narrative · 0

    IN THE COMMUNICATION WITH THE DENTIST ON DECEMBER 26, 2017, THE DENTIST REFUSED TO DISCLOSE THE PATIENT IDENTIFIER AND WEIGHT. UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM A DISTRIBUTOR, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE [(B)(4)]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: NAKANISHI EXAMINED THE DEVICE HISTORY RECORD AND THE REPAIR HISTORY FOR THE SUBJECT Z95L DEVICE [SERIAL NUMBER (B)(4)]. THERE WERE NO PROBLEMS OBSERVED DURING THE MANUFACTURING OR TESTING NOTED IN THE DHR. THE REPAIR HISTORY SHOWED 1 SERVICE RECORD (NOVEMBER 2013) SINCE THE DEVICE WAS SHIPPED. ACCORDING TO THE SERVICE RECORD, AFTER REPAIRING THE HANDPIECE (REPLACEMENT OF CARTRIDGE, DRIVE SHAFT AND DOG CLUTCH), NAKANISHI PERFORMED ALL OF THE NECESSARY OPERATION CHECKS AND CONFIRMED THAT ALL OF THE CRITERIA WERE MET. NAKANISHI CONDUCTED A PRELIMINARY VISUAL INSPECTION OF THE RETURNED DEVICE. BECAUSE THE HEADCAP WAS ALREADY OFF OF THE DEVICE, NAKANISHI WAS ABLE TO OBSERVE THAT THE BEARING BALLS WERE MISSING AND THE BEARING RETAINER WAS BROKEN. THERE WERE NO OTHER VISIBLE ABNORMALITIES, SUCH AS ABRASIONS, DETERIORATION OR DIMENSIONAL ABNORMALITY OF THE HEAD CAP AND HEAD THREAD NOTED IN THE INITIAL VISUAL INSPECTION. NAKANISHI REPLACED THE BROKEN AND MISSING COMPONENTS AND ACTIVATED THE DEVICE FOR AN OPERATION CHECK. NAKANISHI OBSERVED THAT THE OPERATION WAS OUT OF SPECIFICATION AS FOLLOWS. - ROTATIONAL RESISTANCE: 900MA (INSPECTION STANDARD: 150MA OR LESS) - NOISE: 78DB (INSPECTION STANDARD: 59DB OR LESS) - BUR RUNOUT: 144UM (INSPECTION STANDARD: 50UM OR LESS) - VIBRATION: UNMEASURABLE (INSPECTION STANDARD: 15.5G OR LESS) NAKANISHI MEASURED THE DIMENSION OF THE BUR RETURNED WITH THE SUBJECT HANDPIECE AND FOUND THAT THE MAXIMUM WORKING DIAMETER OF THE BUR WAS MORE THAN TWICE AS LARGE AS THE ONE SPECIFIED IN THE OPERATION MANUAL. - DIAMETER OF THE RETURNED BUR: 4.61MM (SPECIFICATION IN OPERATION MANUAL: 2.0MM OR LESS) NAKANISHI OBSERVED WHETHER OR NOT THE HEADCAP ATTACHED TO THE HANDPIECE WOULD LOOSEN IN A CONTINUOUS RUNNING/SIMULATION TESTING, HOWEVER THE REPORTED HEADCAP LOOSENING WAS NOT REPLICATED DURING THE RUN/TEST. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS INVOLVED: NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED AN ADDITIONAL VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED THE FOLLOWING PHENOMENA: - THE BEARING WAS DAMAGED/ABRADED. - THE GEAR WAS EXTREMELY ABRADED. - THERE WAS DEBRIS (ABRASIVE POWDER/FOREIGN MATERIALS) ON THE INSIDE PARTS. 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: ALTHOUGH NAKANISHI COULD NOT REPLICATE THE REPORTED PHENOMENA, NAKANISHI CONSIDERS THE POSSIBILITY, FROM WHAT NAKANISHI OBSERVED IN THE VISUAL INSPECTION THAT ABNORMAL VIBRATION WAS CAUSED BY THE DEBRIS IN AND DAMAGE TO/ABRASION OF THE INSIDE PARTS LEADING TO THE HEADCAP LOOSENING, WHICH COULD RESULT IN THE HEADCAP COMING OFF. USE OF THE OUT-OF-SPECIFICATION BUR INCREASES THE PROBABILITY OF BUR RUNOUT, WHICH COULD ALSO BE THE CAUSE OF THE HEADCAP LOOSENING/COMING OFF. A LACK OF MAINTENANCE CAUSES THE ACCUMULATION OF DEBRIS IN AND DAMAGE TO/ABRASION OF THE INSIDE PARTS, AND FAILURE TO FOLLOW THE INSTRUCTIONS REGARDING THE BUR SPECIFICATION CONTRIBUTE TO THE REPORTED EVENT. IN ORDER TO PREVENT A RECURRENCE OF THE HEADCAP LOOSENING/COMING OFF, 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 FOLLOWING INSTRUCTIONS IN THE OPERATION MANUAL.

    Description of Event or Problem · 0

    ON DECEMBER 26, 2017, NAKANISHI VISITED THE DENTIST AND OBTAINED DETAILED INFORMATION ON THE EVENT. - THE PROCEDURE THE DENTIST WAS PERFORMING AT THE TIME OF THE EVENT WAS POLISHING A COMPOSITE RESIN ON THE UPPER RIGHT PREMOLAR. - THE PATIENT WAS NOT UNDER ANESTHESIA. - NO ABNORMALITY OR MALFUNCTION WAS OBSERVED WITH THE DEVICE PRIOR TO THE EVENT. - DURING THE PROCEDURE, THE HEADCAP SUDDENLY CAME OFF AND DROPPED IN THE PATIENT'S MOUTH. - THE DENTIST RETRIEVED THE HEADCAP FROM THE PATIENT'S MOUTH AND DETERMINED THAT NO MEDICAL INTERVENTION WAS NECESSARY.

    Additional Manufacturer Narrative · 1

    NAKANISHI DID NOT RECEIVE ANY INFORMATION ABOUT PATIENT AND DETAILS OF THE EVENT. NAKANISHI IS SCHEDULED TO VISIT THE DENTIST TO OBTAIN THE INFORMATION.

    Description of Event or Problem · 1

    ON (B)(6) 2017, NAKANISHI RECEIVED A PHONE CALL FROM A DISTRIBUTOR ABOUT A HEADCAP COMING OFF FROM AN NSK HANDPIECE. DETAILS ARE AS FOLLOWS. THE EVENT OCCURRED ON (B)(6) 2017. A DENTIST WAS PERFORMING A DENTAL PROCEDURE USING THE Z95L HANDPIECE (SERIAL NO.: (B)(4)). DURING THE PROCEDURE, THE HEADCAP SUDDENLY CAME OFF FROM THE HANDPIECE.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    905906 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 60 YR Other