BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 14071662 · Received April 11, 2022

    Report

    Report Number
    9611253-2022-00019
    Event Type
    Injury
    Date Received
    April 11, 2022
    Date of Event
    December 23, 2021
    Report Date
    April 19, 2022
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    CA, US
    Reporter Occupation
    501

    Narratives

    Additional Manufacturer Narrative · 0

    THE SAME ADVERSE EVENT IN THIS REPORT HAS BEEN REPORTED TO THE FDA SEPARATELY BY THE DISTRIBUTOR, NSK AMERICA CORPORATION, UNDER REPORT NUMBER 1422375-2022-00009. THE DENTIST REFUSED TO PROVIDE THE PATIENT'S WEIGHT.

    Additional Manufacturer Narrative · 0

    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 Z95L 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 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) OF THE ASSOCIATED DEVICE COMPONENTS WAS CONDUCTED AS FOLLOWS: A) NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INTERNAL PARTS. NAKANISHI OBSERVED THE FOLLOWING: - THE BEARING RETAINER IN THE BALL BEARING ON THE REAR SIDE OF THE CARTRIDGE WAS BROKEN. - THE INTERNAL PARTS WERE SOILED, DISCOLORED, AND ABRADED. B) NAKANISHI TOOK PHOTOGRAPHS OF ALL THE DISASSEMBLED PARTS AND KEPT THEM IN INVESTIGATION REPORT NO. (B)(4). CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: A) NAKANISHI COULD NOT REPLICATE THE TEMPERATURE INCREASE FROM THE EVENT, BUT BASED ON THE FINDINGS IN THE VISUAL INSPECTION, AS WELL AS MANY YEARS OF EXPERIENCE, NAKANISHI IDENTIFIED THAT THE CAUSE OF THE HANDPIECE OVERHEATING WAS ABNORMAL RESISTANCE DURING ROTATION DUE TO THE BROKEN BEARING RETAINER. B) NAKANISHI ALSO CONSIDERS THE POSSIBILITY FROM DEBRIS ON THE INTERNAL PARTS OBSERVED IN THE VISUAL INSPECTION THAT THE CAUSE OF THE BROKEN BEARING RETAINER WAS THE INGRESS OF UNDESIRABLE MATERIALS INTO THE BEARING, LEADING TO ABRASION. C) A LACK OF MAINTENANCE CAUSED THE ACCUMULATION OF DEBRIS ON THE INTERNAL PARTS, WHICH CAUSED DEBRIS INGRESS INTO THE BEARING DURING ROTATION. THIS CONTRIBUTED TO THE HANDPIECE OVERHEATING. D) IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI TOOK THE FOLLOWING ACTIONS: D.1) NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED THE CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. D.2) NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO NSK AMERICA AND DIRECTED NSK AMERICA TO REMIND THE USER OF THE IMPORTANCE OF MAINTENANCE, AS INSTRUCTED IN THE OPERATION MANUAL.

    Description of Event or Problem · 0

    ON MARCH 17, 2022, NAKANISHI BECAME AWARE OF A HANDPIECE OVERHEATING THROUGH A COMPLAINT INPUT INTO THE COMPLAINT DATABASE BY A DISTRIBUTOR (NSK AMERICA). DETAILS ARE AS FOLLOWS: THE EVENT OCCURRED ON (B)(6) 2021. THE DENTIST WAS PERFORMING A FILLING PROCEDURE ON A PATIENT USING THE Z95L HANDPIECE (SERIAL NO. (B)(4)). THE PATIENT WAS UNDER LOCAL ANESTHESIA. DURING THE PROCEDURE, THE HANDPIECE OVERHEATED AND THE PATIENT RECEIVED A BURN INJURY TO THEIR LOWER LIP. THE PATIENT'S INJURY IS REPORTED TO HAVE HEALED NORMALLY WITHOUT NEED FOR ADDITIONAL MEDICAL TREATMENT.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    2402256 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 80 YR Male Other