BEUDAMED
    FDA Adverse Event Malfunction Summary report: N

    NSK

    MDR report key: 23080678 · Received September 17, 2025

    Report

    Report Number
    9611253-2025-00046
    Event Type
    Malfunction
    Date Received
    September 17, 2025
    Date of Event
    August 18, 2025
    Report Date
    September 18, 2025
    Manufacturer
    NAKANISHI INC.
    Product Code
    EFB
    UDI-DI
    04560264528796
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    JA
    Reporter Occupation
    003

    Narratives

    Additional Manufacturer Narrative · 0

    THIS EVENT OCCURRED IN JAPAN, BUT SIMILAR PRODUCTS ARE MARKETED IN THE US UNDER K962543. THE DENTIST REFUSED TO PROVIDE ANY INFORMATION ABOUT PATIENT. UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE [REPORT NO. (B)(4]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: A) NAKANISHI EXAMINED THE DEVICE HISTORY RECORD AND THE REPAIR HISTORY FOR THE SUBJECT S-MAX M500ML DEVICE [SERIAL NO. (B)(6)]. THERE WERE NO PROBLEMS OBSERVED DURING MANUFACTURING OR TESTING NOTED IN THE DHR. THERE WERE ALSO NO REPAIR HISTORY RECORDS SINCE THE DEVICE WAS SHIPPED. B) NAKANISHI CONDUCTED A VISUAL INSPECTION OF THE DEVICE AND OBSERVED THE FOLLOWING: - THE PUSH BUTTON AND INTERNAL SPRING WERE SEPARATED FROM THE DEVICE. - THERE WERE SCRATCH MARKS ON THE SHANK OF THE BUR RETURNED TOGETHER WITH THE HANDPIECE. - THE CUTTING PART OF THE BUR WAS CHIPPED. C) NAKANISHI DISASSEMBLED THE HANDPIECE AND CONDUCTED A VISUAL INSPECTION OF THE INTERNAL PARTS. NAKANISHI OBSERVED THE FOLLOWING: - THERE WERE CONTACT MARKS ON THE HEADCAP AND THE PUSH BUTTON. - THE BEARING RETAINER WAS ABRADED. D) NAKANISHI TOOK PHOTOGRAPHS OF ALL THE DISASSEMBLED PARTS AND KEPT THEM IN THE INVESTIGATION REPORT NO. (B)(4). CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: A) NAKANISHI IDENTIFIED THAT THE CAUSE OF THE PUSH BUTTON SEPARATION WAS RETAINING SCREW LOOSENING DUE TO THE COMBINATION OF A STRONG IMPACT ON THE DEVICE TOGETHER WITH REPETITIVE CUTTING VIBRATION. NAKANISHI CONSIDERS THE POSSIBILITY FROM MANY YEARS OF EXPERIENCE AND BASED ON THE FINDINGS IN THE VISUAL INSPECTION, THAT THE ABRADED BEARING, THE PUSH BUTTON PRESSED DURING ROTATION, HIGH-LOAD CUTTING COULD INCREASE THE CUTTING VIBRATION. B) MISUSE BY THE USER LED TO THE ABOVE ISSUE, WHICH CONTRIBUTED TO THE REPORTED EVENT. C) IN ORDER TO PREVENT A RECURRENCE OF THE PUSH BUTTON LOOSENING/SEPARATION, NAKANISHI TOOK THE FOLLOWING ACTIONS: C.1) NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED THE CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. C.2) NAKANISHI WILL REPORT THE ABOVE EVALUATION RESULTS TO THE DENTIST AND REMIND THE DENTIST OF THE IMPORTANCE O0F USING THE DEVICE AS INSTRUCTED IN THE OPERATION MANUAL.

    Description of Event or Problem · 0

    ON AUGUST 22, 2025, NAKANISHI RECEIVED A PHONE CALL FROM A DEALER ABOUT A MALFUNCTION OF AN NSK HANDPIECE. THE DETAILS NAKANISHI OBTAINED ARE AS FOLLOWS: - THE EVENT OCCURRED ON AUGUST 18, 2025. - A DENTIST WAS PERFORMING A CROWN REMOVAL PROCEDURE ON A PATIENT USING THE S-MAX M500ML HANDPIECE (SERIAL NO. (B)(6). - DURING THE PROCEDURE, THE PUSH BUTTON AND INTERNAL SPRING CAME OFF FROM THE HEADCAP OF THE HANDPIECE SUDDENLY AND LANDED IN THE PATIENT'S MOUTH. - THE PARTS WERE RECOVERED IMMEDIATELY, AND THE PATIENT WAS NOT INJURED IN THE EVENT. - ACCORDING TO THE DENTIST, THERE WERE NO ABNORMALITIES OBSERVED IN THE DEVICE PRIOR TO USE.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    2641100 NSK HANDPIECE, AIR-POWERED, DENTAL EFB NAKANISHI INC. S-MAX M500ML 04560264528796

    Patients

    Seq Age Sex Outcome Treatment
    1 NA Unknown Other