BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 8500501 · Received April 10, 2019

    Report

    Report Number
    9611253-2019-00023
    Event Type
    Injury
    Date Received
    April 10, 2019
    Date of Event
    March 18, 2019
    Report Date
    May 17, 2019
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    GA, US
    Reporter Occupation
    OTHER HEALTH CARE PROFESSIONAL

    Narratives

    Additional Manufacturer Narrative · 0

    UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM A DISTRIBUTOR, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE [C190320-20]. 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. THERE WERE ALSO NO REPAIR HISTORY RECORDS SINCE THE DEVICE WAS SHIPPED. NAKANISHI 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, NAKANISHI 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: NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED THE FOLLOWING PHENOMENA: THE HEADCAP REMAINED DEPRESSED IN THE HANDPIECE (SLIDING FAILURE). THE HEADCAP WAS DEFORMED. THERE WERE SIGNS OF CONTACT BETWEEN THE SURFACE OF THE PUSHER OF THE CARTRIDGE AND INSIDE THE HEADCAP WHICH WOULD HAVE BEEN CAUSED BY THE HEADCAP BEING PRESSED. 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 COULD NOT REPLICATE THE TEMPERATURE RISE AT THE TIME OF THE EVENT, HOWEVER BASED ON ABNORMALITY IN THE INSIDE PARTS OBSERVED IN THE VISUAL INSPECTION, AS WELL AS MANY YEARS OF EXPERIENCE, NAKANISHI IDENTIFIED THAT THE CAUSE OF THE OVERHEATING OF THE RETURNED DEVICE WAS FRICTION HEAT GENERATED BY CONTACT BETWEEN THE HEADCAP AND THE CARTRIDGE, WHICH WAS CAUSED BY THE HEADCAP REMAINING DEPRESSED DURING ROTATION (SLIDING FAILURE). NAKANISHI ALSO CONSIDERED THE DEFORMED HEADCAP DUE TO IMPACT/DROP AS A CAUSE OF SLIDING FAILURE. MISUSE BY THE USER LEADS TO THE CONTACT BETWEEN THE HEADCAP AND THE CARTRIDGE DUE TO SLIDING FAILURE, WHICH CONTRIBUTES TO THE REPORTED 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 NSK AMERICA AND DIRECTED NSK AMERICA TO REMIND THE USER OF THE IMPORTANCE OF USING THE DEVICE, AS INSTRUCTED IN THE OPERATION MANUAL.

    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 MARCH 30, 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 PROCEDURE ON A TOOTH OF THE PATIENT'S LOWER JAW USING THE Z95L HANDPIECE (SERIAL NO. (B)(4)). THE PATIENT WAS NOT UNDER ANESTHESIA AND THE PATIENT'S MOUTH WAS COVERED WITH A RUBBER DAM. THE BUR WAS NOT ENGAGING UNTIL THE MOTOR WAS ACTIVATED, AND THEN THE BUR BEGAN ROTATING FOR 7-9 SECONDS BEFORE THE HANDPIECE STALLED. THE DENTIST FELT THE HANDPIECE OVERHEATING AND DISCONTINUED USE OF THE DEVICE. THE DENTIST COMPLETED THE PROCEDURE USING A DIFFERENT HANDPIECE. WHEN THE PROCEDURE WAS COMPLETED AND THE RUBBER DAM WAS REMOVED FROM THE PATIENT'S MOUTH, THE DENTIST FOUND A BURN INJURY TO THE LEFT LATERAL AREA OF THE PATIENT'S TONGUE. NO BURN TREATMENT WAS ADMINISTERED AT THE TIME OF THE INJURY. WHEN THE PATIENT RETURNED TO THE OFFICE FOR A FOLLOW-UP, THE DENTIST DETERMINED THE INJURY WAS HEALING NORMALLY. THE DENTIST CONTINUES TO MONITOR THE PROGRESSION OF HEALING.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    293116 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 59 YR Other