BEUDAMED
    FDA Adverse Event Malfunction Summary report: N

    NSK Z95L

    MDR report key: 4640913 · Received March 24, 2015

    Report

    Report Number
    9611253-2015-00078
    Event Type
    Malfunction
    Date Received
    March 24, 2015
    Date of Event
    February 25, 2015
    Report Date
    March 17, 2015
    Manufacturer
    NAKANISHI, INC. (NSK)
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    JA
    Reporter Occupation
    DENTIST

    Narratives

    Additional Manufacturer Narrative · 1

    UPON RECEIPT FROM THE DENTIST OF THE DEVICE INVOLVED IN THE MDR EVENT, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE THAT INCLUDED AN ATTEMPT TO MEASURE THE TEMPERATURE OF THE OPERATING DEVICE (B)(4). THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: NAKANISHI EXAMINED THE DEVICE HISTORY RECORD FOR THE SUBJECT TI-MAX Z95L DEVICE (B)(4). THERE WERE NO PROBLEMS OBSERVED DURING THE MANUFACTURING OR TESTING NOTED IN THE DHR. NAKANISHI CONDUCTED A VISUAL INSPECTION OF THE RETURNED DEVICE AND PERFORMED A SIMPLE MOVEMENT TEST. THERE WERE NO VISIBLE ABNORMALITIES, SUCH AS CRACKS OR DEBRIS, ON THE OUTSIDE OF THE HANDPIECE. NAKANISHI THEN SET A TEST BUR IN THE HANDPIECE AND ROTATED IT BY HAND. NAKANISHI OBSERVED THAT THE BUR DID NOT ROTATE SMOOTHLY. THE DEVICE WAS CONFIGURED FOR TEMPERATURE TESTING IN THE EXACT STATE IN WHICH IT WAS RETURNED. SPECIFICALLY, NO LUBRICATION OR CLEANING WAS PERFORMED ON THE RETURNED DEVICE BEFORE THIS FIRST TEST IN ORDER TO CHARACTERIZE THE DEVICE UNDER CONDITIONS THAT WOULD DUPLICATE THE USE SITUATION AT THE LIME OF THE EVENT. TEMPERATURE SENSORS WERE FIRST ATTACHED TO THE EXTERIOR OF THE DEVICE AT VARIOUS TEST POINTS (E.G., MOST PROXIMAL TO THE PATIENT AND ALONG POINTS FURTHER TOWARD THE DISTAL END OF THE DEVICE). THE TEST SET UP WAS PREPARED TO TAKE TEMPERATURE MEASUREMENTS AT ALL POINTS SIMULTANEOUSLY, INCLUDING A REFERENCE MEASUREMENT AT AMBIENT ROOM TEMPERATURE. NAKANISHI ATTACHED A THERMOCOUPLE (SENSOR TO MEASURE A TEMPERATURE) TO EACH OF THE TESTING POINTS. NAKANISHI ROTATED THE HANDPIECE AT 40,000 RPM, WHICH IS MAXIMUM RPM FOR THE MOTOR THAT DRIVES THE HANDPIECE (200,000 RPM FOR THE HANDPIECE), WITH WATER SPRAY AND MEASURED THE EXOTHERMIC SITUATION. NAKANISHI MEASURED THE TEMPERATURE RISE OF THE RETURNED HANDPIECE SET AT 200,000 RPM (MOTOR REVOLUTION 40,000 RPM). NAKANISHI CONFIRMED THE HANDPIECE ROTATED WITH NOISE AFTER THE BEGINNING OF THE MEASUREMENT. IN FACT. THE HANDPIECE STOPPED ROTATING SO SUDDEN THAT THE TEST ENDED ONLY 50 SECONDS INTO THE PLANNED 3-MINUTE EVALUATION PERIOD. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS(S) INVOLVED: NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED DAMAGE ON THE CARTRIDGE BEARING. THE AMOUNT OF OIL OBSERVED INSIDE THE HANDPIECE INDICATED THAT THE DEVICE WAS NOT ADEQUATELY CLEANED. DUE TO THE OIL LEVEL OBSERVED, AS WELL AS THE PRESENCE OF SOME ABRASIVE POWERS IN THE HANDPIECE, NAKANISHI REASSEMBLED AND WASHED THE HANDPIECE USING NAKANISHI PANA SPRAY. NAKANISHI OBSERVED DIRT/DEBRIS BEING EXPELLED FROM THE HEAD OF THE HANDPIECE BY USING A WHITE FILTER TO CATCH ANYTHING THAT WAS EXPELLED. AFTER CLEANING AND LUBRICATING THE HANDPIECE AS DEFINED IN THE OPERATIONS MANUAL. NAKANISHI MEASURED THE TEMPERATURE OF THE HANDPIECE. EVEN AFTER CLEANING. NAKANISHI STILL OBSERVED A QUICK RISE IN TEMPERATURE. WHEN NAKANISHI RECEIVED THE HANDPIECE, THE CARTRIDGE BEARING WAS ALREADY DAMAGED AS DISCOVERED BY THE DISASSEMBLY PREVIOUSLY DISCUSSED. THEREFORE, THE UNACCEPTABLE TEMPERATURE RESULTED EVEN THOUGH NAKANISHI PERFORMED THE MAINTENANCE AS OUTLINED IN THE OPERATIONS MANUAL (USE OF PANA-SPRAY). NAKANISHI THEN REPLACED THE DAMAGED BEARING AND MEASURED THE EXOTHERMIC SITUATION YET AGAIN. THERE WAS NO ABNORMAL TEMPERATURE SPECIFICATIONS ONCE THE DAMAGED BEARING HAD BEEN REPLACED. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS : NAKANISHI IDENTIFIED THAT TILE CAUSE OF OVERHEATING OF THE RETURNED DEVICE WAS DUE TO DAMAGE TO THE BEARING. THE DAMAGE OBSERVED CAUSED ABNORMAL ROTATIONAL RESISTANCE, WHICH WOULD RESULT IN THE HANDPIECE OVERHEATING. THE DAMAGE OBSERVED IS CONSISTENT WITH A LACK OF PROPER LUBRICATION AND CLEANING AFTER USE. A LACK OF MAINTENANCE CAUSES ACCUMULATION OF ABRASIVE POWDERS IN THE HEAD, WHICH CAUSES THE PART TO BECOME WORN. THE WORN PARTS LEAD TO THE BEARINGS BECOMING DAMAGED, WHICH WILL CONTRIBUTE TO THE HANDPIECE OVERHEATING.

    Description of Event or Problem · 1

    THE FOLLOWING INFORMATION IS FROM DENTIST TO NAKANISHI INC.(NSK), REGARDING A DEVICE MANUFACTURED BY NSK. EVENT SUMMARY: ACCORDING TO THIS DENTIST, DURING THE ODONTOGENESIS PROCEDURE ON THE PATIENT THE HANDPIECE STOPPED ROTATING SUDDENLY. THE DENTISTS OBSERVED THERE WAS A BURN ON THE BUCCAL MUCOSA OF THE PATIENT THAT WAS THE SIZE OF THE HANDPIECE HEAD. THE DENTIST GAVE THE PATIENT AN OINTMENT AND MONITORED THE HEALING PROGRESS. COMPLAINT REVIEW: THERE WAS NO REPAIR HISTORY ON FILE FOR THIS HANDPIECE. INVESTIGATION: THE HANDPIECE WAS FORWARDED TO THE MANUFACTURER (NAKANISHI) FOR AN ANALYSIS AND INVESTIGATION ON MARCH 2, 2015. AS OF THIS REPORT NO ADDITIONAL INFORMATION HAS BEEN RECEIVED.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    198191 NSK Z95L HANDPIECE, CONTRA AND RIGHT ANGLE ATTACHEMENT DENTAL EGS NAKANISHI, INC. (NSK) Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 Other