BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK Z95L

    MDR report key: 4763236 · Received May 8, 2015

    Report

    Report Number
    9611253-2015-00085
    Event Type
    Injury
    Date Received
    May 8, 2015
    Date of Event
    April 7, 2015
    Report Date
    May 7, 2015
    Manufacturer
    NAKANISHI, INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    JA
    Reporter Occupation
    SERVICE PERSONNEL

    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. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: NAKANISHI EXAMINED THE DEVICE HISTORY RECORD FOR THE SUBJECT TI-MAX Z95L DEVICE (SERIAL NUMBER (B)(4)). THERE WERE NO PROBLEM OBSERVED DURING THE MFG OR TESTING NOTED IN THE DHR. 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 TIME OF THE EVENT. TEMPERATURE SENSORS WERE FIRST ATTACHED TO THE EXTERIOR OF THE DEVICE AT TWO TEST POINTS (I.E., MOST PROXIMAL TO THE PATIENT AND 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, NAKANISHI CONFIRMED THE TEMPERATURE OF SIDE OF HEAD AND PART OF HEAD CAP ROSE SUDDENLY, WHICH IS ABNORMAL. 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. WHEN NAKANISHI RECEIVED THE HANDPIECE, THE CARTRIDGE BEARING WAS ALREADY DAMAGED AS STATED ABOVE. 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 MEASURED ONCE THE DAMAGED BEARING HAD BEEN REPLACED. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: NAKANISHI IDENTIFIED THAT THE 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 CONSISTENCE WITH THE LACK OF PROPER LUBRICATION AND CLEANING AFTER USE. A LACK OF MAINTENANCE CAUSES ACCUMULATION OF ABRASIVE POWDERS IN THE HEAD, WHICH CAUSES THE PARTS TO BE WORN. THE WORN PARTS LEAD TO THE BEARINGS DAMAGED, WHICH WILL CONTRIBUTE THE HANDPIECE OVERHEATING. THIS IS DOCUMENTED IN THE USER MANUAL. NAKANISHI REMINDED THE USER THE MAINTENANCE INSTRUCTIONS INCLUDED IN THE USER MANUAL.

    Description of Event or Problem · 1

    THE FOLLOWING INFO IS FROM A DENTIST TO NAKANISHI INC (NSK), REGARDING A DEVICE MANUFACTURED BY NSK. EVENT SUMMARY: ACCORDING TO THE DENTIST, THE PT COMPLAINED THAT THE HANDPIECE WAS HOT DURING THE CORE REMOVAL OPERATION BEFORE THE ROOT CANAL TREATMENT PROCEDURE. UPON THIS COMPLAINT, THE DENTIST CONFIRMED THE HANDPIECE TEMPERATURE WITH DENTIST'S UPPER ARM THAT RESULTED IN A BURN INJURY (APPROX 5MM IN DIAMETER). NAKANISHI RECEIVED THE ADD'L INFO FROM THE DENTIST ON (B)(6) 2015 THAT THE PT HAD ALSO BEEN BURNED (APPROX 2MM IN DIAMETER). 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 (B)(6) 2015.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    303608 NSK Z95L HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI, INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 50 YR Other