BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 8430211 · Received March 18, 2019

    Report

    Report Number
    9611253-2019-00014
    Event Type
    Injury
    Date Received
    March 18, 2019
    Date of Event
    January 22, 2019
    Report Date
    April 15, 2019
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    NH, US
    Reporter Occupation
    DENTIST

    Narratives

    Additional Manufacturer Narrative · 0

    EXEMPTION NUMBER E2016004. (B)(4). ACCORDING TO THE DISTRIBUTOR, THE DENTIST REFUSED TO PROVIDE THE PATIENT'S WEIGHT.

    Description of Event or Problem · 0

    ON FEBRUARY 20, 2019, NAKANISHI RECEIVED AN E-MAIL FROM A DISTRIBUTOR ((B)(4)) ABOUT A HANDPIECE OVERHEATING. DETAILS ARE AS FOLLOWS. THE EVENT OCCURRED ON (B)(6) 2019. THE DENTIST WAS PERFORMING A CROWN PREPARATION ON A PATIENT USING THE Z95L HANDPIECE (SERIAL NO. (B)(4)). THE PATIENT WAS UNDER LOCAL ANESTHESIA. DURING THE PROCEDURE, THE DEVICE SUDDENLY STARTED TO MAKE A GRATING/GRINDING NOISE AND THEN, THE DENTIST FELT A "CHATTERING" SENSATION COMING FROM THE HANDPIECE. THE DENTIST OBSERVED A 3RD DEGREE OVAL SHAPED BURN, APPROXIMATELY 1.5CM IN SIZE ON THE PATIENT'S LOWER LIP AND SKIN RIGHT BELOW THE LIP. THE DENTIST IMMEDIATELY DISCONTINUED USE OF THE HANDPIECE. THE DENTIST APPLIED AN OINTMENT TO THE BURN INJURY AND A COLD COMPRESS TO THE AFFECTED AREA, AND ADVISED THE PATIENT TO TAKE AN OVER-THE-COUNTER ANTI-INFLAMMATORY MEDICATION. THE INJURY WAS FOUND TO BE HEALING NORMALLY UPON FOLLOW-UP VISIT WITH THE PATIENT. THE DENTIST DETERMINED THAT NO FURTHER MEDICAL ATTENTION WAS REQUIRED FOR THE INJURY.

    Additional Manufacturer Narrative · 1

    UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM A DISTRIBUTOR, (B)(4) CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE [C190221-10]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: (B)(4) 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. THERE WERE ALSO NO REPAIR HISTORY RECORDS SINCE THE DEVICE WAS SHIPPED. (B)(4) SET A TEST BUR IN THE HANDPIECE, CONNECTED THE HANDPIECE TO THE MOTOR AND TRIED TO ROTATE THE MOTOR. HOWEVER, THE HANDPIECE WAS LOCKED AND THE MOTOR DID NOT ROTATE AT ALL. THEREFORE, (B)(4) WAS NOT ABLE TO CONDUCT TEMPERATURE TESTING OF THE DEVICE. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS INVOLVED: (B)(4) DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. (B)(4) OBSERVED THE FOLLOWING PHENOMENA: - THE BEARING RETAINER (BALL RETAINING PART) ON THE CARTRIDGE REAR SIDE WAS BROKEN. - THE CLUTCH SHAFT WAS STUCK WITH THE BODY WITHOUT BEING REMOVED FROM THE BODY. - THE HEAD GEAR AND UPPER DRIVE GEAR WERE BROKEN/DAMAGED. - THE DOG CLUTCH WAS CORRODED. - THERE WAS DEBRIS (ABRASIVE POWDER, PIECES OF BROKEN BEARING) ON THE INSIDE PARTS. (B)(4) TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS AND KEPT THEM IN THE INVESTIGATION REPORT #C190221-10. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: (B)(4) IDENTIFIED THAT THE CAUSE OF THE OVERHEATING OF THE RETURNED DEVICE WAS ABNORMAL RESISTANCE DURING ROTATION CAUSED BY THE BROKEN BEARINGS DUE TO THE INGRESS OF UNDESIRABLE MATERIALS INTO THE BEARING. A LACK OF MAINTENANCE CAUSES ABRASION OF THE INSIDE PARTS, WHICH GENERATES DEBRIS SUCH AS ABRASIVE POWDER, PIECES OF BROKEN BEARING, RESULTING IN DEBRIS INGRESS INTO THE BEARING DURING ROTATION. IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, (B)(4) TOOK THE FOLLOWING ACTIONS: (B)(4) REVIEWED THE OPERATION MANUAL AND RECONFIRMED CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. (B)(4) REPORTED THE ABOVE EVALUATION RESULTS TO (B)(4) AMERICA AND DIRECTED (B)(4) AMERICA TO REMIND THE USER OF THE IMPORTANCE OF MAINTENANCE, AS INSTRUCTED IN THE OPERATION MANUAL.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    220700 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 56 YR Other