BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 15723140 · Received November 3, 2022

    Report

    Report Number
    9611253-2022-00079
    Event Type
    Injury
    Date Received
    November 3, 2022
    Date of Event
    October 11, 2022
    Report Date
    December 1, 2022
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K202960
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    NC, US
    Reporter Occupation
    PHYSICIAN ASSISTANT
    Health Professional
    Yes

    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 (B)(4). THE DENTIST REFUSED TO PROVIDE INFORMATION ABOUT THE PATIENT'S WEIGHT AND RACE.

    Additional Manufacturer Narrative · 0

    UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM THE DISTRIBUTOR, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE, WHICH INCLUDED MEASURING THE OPERATING TEMPERATURE OF THE DEVICE [REPORT NO. C221014-08]. 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 [E21X1486]. 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 TEMPERATURE TESTING OF THE RETURNED DEVICE IN THE FOLLOWING MANNER: B.1) TEMPERATURE SENSORS WERE ATTACHED TO THE EXTERIOR OF THE DEVICE AT VARIOUS TEST POINTS. THIS INCLUDED THE POINT MOST PROXIMAL TO THE PATIENT (TESTING POINT (1)) AND POINTS FURTHER TOWARD THE DISTAL END OF THE DEVICE (TESTING POINTS (2) THROUGH (4)). THE TEST SETUP WAS PREPARED TO TAKE TEMPERATURE MEASUREMENTS AT ALL POINTS SIMULTANEOUSLY, INCLUDING A REFERENCE MEASUREMENT AT AMBIENT ROOM TEMPERATURE. B.2) NAKANISHI ATTACHED A THERMOCOUPLE (SENSOR TO MEASURE TEMPERATURE) TO EACH OF THE TESTING POINTS. NAKANISHI ROTATED THE DEVICE'S MOTOR AT 40,000MIN-1, WHICH IS THE MAXIMUM RPM FOR THE MOTOR THAT DRIVES THE HANDPIECE (200,000MIN-1 FOR THE HANDPIECE), WITH WATER SPRAY, AND MEASURED THE EXOTHERMIC RESPONSE. B.3) NAKANISHI MEASURED THE TEMPERATURE RISE OF THE RETURNED HANDPIECE SET AT 200,000MIN-1 (MOTOR REVOLUTION 40,000MIN-1). NAKANISHI OBSERVED AN ABNORMAL TEMPERATURE RISE AT THE TEST POINTS (1) AND (2) 1 MINUTE INTO THE TEST. TEMPERATURE MEASUREMENTS ABOUT 1 MINUTE AFTER THE START OF THE TEST WERE AS FOLLOWS: - TEST POINT (1): 61.0 DEGREES C - TEST POINT (2): 63.8 DEGREES C - TEST POINT (3): 40.1 DEGREES C - TEST POINT (4): 36.1 DEGREES C THE INCREASE IN TEMPERATURE WAS SO SUDDEN THAT THE TEST WAS CONCLUDED ABOUT 2 MINUTES INTO THE PLANNED 5-MIMUTE EVALUATION PERIOD. 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 HEADCAP WAS DEFORMED AND STUCK IN THE HANDPIECE (SLIDING FAILURE). - THE BEARING RETAINER IN THE BALL BEARING ON THE REAR SIDE OF THE CARTRIDGE WAS BROKEN. - THERE WAS EVIDENCE OF CONTACT BETWEEN THE HEADCAP AND CARTRIDGE PUSHER. B) NAKANISHI TOOK PHOTOGRAPHS OF ALL THE DISASSEMBLED PARTS AND KEPT THEM IN THE INVESTIGATION REPORT NO. C221014-08. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: A) NAKANISHI DETERMINED THAT THE CAUSE OF OVERHEATING OF THE RETURNED DEVICE WAS ABNORMAL RESISTANCE DURING ROTATION DUE TO THE BROKEN BEARING RETAINER. NAKANISHI IDENTIFIED FROM THE FINDINGS IN THE VISUAL INSPECTION THAT THE CAUSE OF THE BROKEN RETAINER WAS THE PUSH BUTTON BEING STUCK TO THE HANDPIECE DURING ROTATION LEADING TO THE CONTACT BETWEEN THE HEADCAP AND THE CARTRIDGE. NAKANISHI CONSIDERS THE POSSIBILITY FROM MANY YEARS OF EXPERIENCE THAT THE HEADCAP WAS DEPRESSED BY STRESS DUE TO AN EXTERNAL IMPACT, SUCH AS DROPPING THE DEVICE. B) MISUSE BY THE USER LED TO THE ABOVE ISSUES, WHICH CONTRIBUTED TO THE REPORTED OVERHEATING. C) IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI TOOK THE FOLLOWING ACTIONS: C.1) NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED THE CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. C.2) NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO THE DISTRIBUTOR AND DIRECTED THE DISTRIBUTOR TO REMIND THE USER OF THE IMPORTANCE OF USING THE DEVICE AS INSTRUCTED IN THE OPERATION MANUAL.

    Description of Event or Problem · 0

    ON OCTOBER 14, 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) 2022. THE DENTIST WAS PERFORMING A DENTAL PROCEDURE ON A PATIENT USING THE Z95L HANDPIECE (SERIAL NO. (B)(4). DURING THE PROCEDURE, THE HEAD OF THE HANDPIECE OVERHEATED, AND THE PATIENT RECEIVED A MINOR BURN TO THEIR LOWER RIGHT INNER LIP. THE BURN REPORTED TO BE APPROXIMATELY 4MM IN SIZE WITH BLISTERING. THE PATIENT IS REPORTED TO BE IN GOOD HEALTH.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    510682 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 6 YR Female Other