BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 7305774 · Received March 1, 2018

    Report

    Report Number
    9611253-2018-00007
    Event Type
    Injury
    Date Received
    March 1, 2018
    Date of Event
    February 5, 2018
    Report Date
    March 28, 2018
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    JA
    Reporter Occupation
    OTHER

    Narratives

    Additional Manufacturer Narrative · 0

    UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM A DISTRIBUTOR, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE THAT INCLUDED MEASURING THE OPERATING TEMPERATURE OF THE DEVICE [C180214-04]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: A) NAKANISHI EXAMINED THE DEVICE HISTORY RECORD AND THE REPAIR HISTORY FOR THE SUBJECT DA-800C5 DEVICE [SERIAL NUMBER (B)(4)]. THERE WERE NO PROBLEMS OBSERVED DURING THE MANUFACTURING OR TESTING NOTED IN THE DHR. THERE WERE NO RECORDS INDICATING NAKANISHI (THE MANUFACTURER) REPAIRED THE DEVICE SINCE THE DEVICE WAS SHIPPED. NAKANISHI RECEIVED THE REPAIR RECORDS FROM THE DISTRIBUTOR STATING THAT THE DISTRIBUTOR HAD REPLACED THE BUSHINGS, DOG CLUTCH, CARTRIDGE AND DRIVE SHAFT WITH NEW ONES ON (B)(6) 2017. 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 A TEMPERATURE) TO EACH OF THE TESTING POINTS. NAKANISHI ROTATED THE DEVICE'S MOTOR AT 40,000 MIN-1, WHICH IS THE MAXIMUM RPM FOR THE MOTOR THAT DRIVES THE HANDPIECE (200,000 MIN-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 200,000 MIN-1 (MOTOR REVOLUTION 40,000 MIN-1). NAKANISHI OBSERVED AN ABNORMAL TEMPERATURE RISE AT TEST POINT (1) AND (2) A FEW SECONDS AFTER THE START. TEMPERATURE MEASUREMENTS 30 SECONDS AFTER THE START ARE AS FOLLOWS: - TEST POINT (1): 65.8 DEGREES C - TEST POINT (2): 83.4 DEGREES C - TEST POINT (3): 44.9 DEGREES C - TEST POINT (4): 29.9 DEGREES C THE RISE IN TEMPERATURE WAS SO SUDDEN THAT THE TEST WAS CONCLUDED 30 SECONDS INTO THE PLANNED 5 MINUTE EVALUATION PERIOD. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS INVOLVED: A) NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED THE FOLLOWING PHENOMENA: THERE WERE ABRASION OF/DEBRIS (ABRASIVE POWDERS) ON THE BALL POCKETS OF THE BEARING RETAINER (BALL RETAINING PLASTIC PART) ON THE CARTRIDGE REAR SIDE. THERE WAS ALSO ABRASION OF/DEBRIS (ABRASIVE POWDERS/FOREIGN MATERIALS) ON EACH ENGAGEMENT AREA OF THE GEARS. B) NAKANISHI TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS AND KEPT THEM IN THE INVESTIGATION REPORT #(B)(4). CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: 1) NAKANISHI IDENTIFIED THAT THE CAUSES OF THE OVERHEATING OF THE RETURNED DEVICE WERE; ABNORMAL RESISTANCE DURING ROTATION CAUSED BY THE SOILED BEARINGS DUE TO THE INGRESS OF UNDESIRABLE MATERIALS INTO THE BEARING. FRICTIONAL HEAT GENERATED BY ENGAGEMENT OF THE SOILED GEARS. 2) A LACK OF MAINTENANCE CAUSES THE ACCUMULATION OF DEBRIS ON THE INSIDE PARTS, WHICH CAUSES DEBRIS INGRESS INTO THE BEARING DURING ROTATION. THIS CONTRIBUTES TO THE HANDPIECE OVERHEATING. 3) IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI TOOK THE FOLLOWING ACTIONS: 3.1) NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. 3.2) NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO THE DENTIST AND REMINDED THE DENTIST OF THE IMPORTANCE OF MAINTENANCE, AS INSTRUCTED IN THE OPERATION MANUAL.

    Additional Manufacturer Narrative · 1

    WHEN THE DISTRIBUTOR CONTACTED THE DENTIST FOR INFORMATION ABOUT THE EVENT, THE DENTIST REFUSED TO PROVIDE THE PATIENT IDENTIFIER AND WEIGHT. THIS EVENT OCCURRED IN (B)(6), BUT SIMILAR PRODUCTS ARE MARKETED IN THE US UNDER K972569.

    Description of Event or Problem · 1

    ON FEBRUARY 14, 2018, AN NSK HANDPIECE DA-800C5 WAS RETURNED FROM A DISTRIBUTOR TO NAKANISHI FOR REPAIR. THERE WAS A NOTE WITH THE DEVICE STATING THAT THE DEVICE HAD OVERHEATED. THE DETAILS OF THE EVENT NAKANISHI OBTAINED FROM THE DISTRIBUTOR ARE AS FOLLOWS: THE EVENT OCCURRED IN (B)(6) 2018. A DENTIST PERFORMED A COMPOSITE RESIN RESTORATION OF TEETH #4 AND #5 OF THE PATIENT'S UPPER LEFT JAW USING THE HANDPIECE DA-800C5 (SERIAL NO. (B)(4)). WHEN THE DENTIST WORKED ON ANOTHER PATIENT, THE FIRST PATIENT COMPLAINED ABOUT BURNING FEELING IN THE MOUTH. THE DENTIST TOUCHED THE HANDPIECE AND FOUND THE HANDPIECE OVERHEATING. THE PATIENT LEFT THE DENTAL OFFICE WITHOUT RECEIVING ANY BURN TREATMENT. THE NEXT DAY, THE DENTIST RECEIVED A PHONE CALL FROM THE PATIENT SAYING THAT THERE WAS EROSION PRODUCED ON THE MUCOSA ON THE CORNER OF THE MOUTH. THE DENTIST ASKED THE PATIENT TO RETURN THE DENTAL OFFICE FOR FOLLOW-UP VISIT ON (B)(6) 2018. ACCORDING TO THE DENTIST, THERE WERE NO ABNORMALITIES IN THE HANDPIECE OBSERVED PRIOR TO USE.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    150099 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. DA-800C5

    Patients

    Seq Age Sex Outcome Treatment
    1 28 YR Other