BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 6826634 · Received August 29, 2017

    Report

    Report Number
    9611253-2017-00042
    Event Type
    Injury
    Date Received
    August 29, 2017
    Date of Event
    July 24, 2017
    Report Date
    September 21, 2017
    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 · 1

    THE DENTIST DID NOT DISCLOSE INFORMATION ABOUT THE PATIENT. THIS EVENT OCCURRED IN (B)(6), BUT SIMILAR PRODUCTS ARE MARKETED IN THE US UNDER K962540.

    Additional Manufacturer Narrative · 1

    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 [(B)(4)]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: NAKANISHI EXAMINED THE DEVICE HISTORY RECORD AND THE REPAIR HISTORY FOR THE SUBJECT EVA-Y DEVICE [SERIAL NUMBER (B)(4)]. THERE WERE NO PROBLEMS OBSERVED DURING THE MANUFACTURING OR TESTING NOTED IN THE DHR. THERE WERE ALSO NO REPAIR HISTORY RECORDS SINCE THE DEVICE WAS SHIPPED. NAKANISHI CONDUCTED TEMPERATURE TESTING OF THE RETURNED DEVICE IN THE FOLLOWING MANNER: 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. 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 (10,000 MIN-1 FOR THE HANDPIECE), AND MEASURED THE EXOTHERMIC SITUATION. NAKANISHI MEASURED THE TEMPERATURE RISE OF THE RETURNED HANDPIECE SET AT 10,000 MIN-1 (MOTOR REVOLUTION 40,000 MIN-1). NAKANISHI DID NOT OBSERVE TEMPERATURES HIGH ENOUGH TO CAUSE A BURN INJURY AT ANY TESTING POINT DURING THE 5 MINUTE EVALUATION PERIOD. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) AND THE ASSOCIATED DEVICE COMPONENTS INVOLVED: NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INSIDE PARTS. NAKANISHI OBSERVED ABRASION OF THE PLUNGER AND OSCILLATOR CAM IN THE INSPECTION. NAKANISHI TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS AND KEPT THEM IN A FILE. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: NAKANISHI COULD NOT IDENTIFY THE EXACT CAUSE OF OVERHEATING OF THE RETURNED DEVICE BECAUSE NAKANISHI WAS NOT ABLE TO REPLICATE THE TEMPERATURE RISE AT THE TIME OF THE EVENT. THE ONLY ABNORMALITY NAKANISHI OBSERVED DURING THE EVALUATION WAS ABRASION OF THE INTERNAL PARTS IN THE VISUAL INSPECTION. NAKANISHI DID NOT IDENTIFY THE CAUSE, BUT BASED ON WHAT NAKANISHI OBSERVED IN THE VISUAL INSPECTION, AS WELL AS MANY YEARS OF EXPERIENCE, NAKANISHI CONSIDERS IT IS POSSIBLE THAT THE CAUSE OF THE HANDPIECE OVERHEATING WAS ABNORMAL RESISTANCE DURING ROTATION DUE TO ABRADED INTERNAL PARTS AND/OR DEBRIS. A LACK OF MAINTENANCE CAUSES THE ABOVE PHENOMENON, WHICH CONTRIBUTES TO THE HANDPIECE OVERHEATING. IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI TOOK THE FOLLOWING ACTIONS: NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO THE DENTIST AND REMINDED THE DENTIST OF THE IMPORTANCE OF MAINTENANCE, AS INSTRUCTED IN THE OPERATION MANUAL.

    Description of Event or Problem · 1

    ON (B)(6) 2017, AN NSK HANDPIECE HEAD, EVA-Y WAS RETURNED FROM A DISTRIBUTOR TO NAKANISHI FOR REPAIR. THERE WAS A NOTE WITH THE DEVICE STATING THE DEVICE WAS OVERHEATING. THE DETAILS ARE AS FOLLOWS. - THE EVENT OCCURRED ON (B)(6) 2017. - A DENTIST WAS POLISHING A LOWER RIGHT TOOTH #5 USING A 2-PIECE DEVICE OF EVA-Y (SERIAL NO. (B)(4)) AND ER4 (SERIAL NO. (B)(4)). - DURING THE PROCEDURE, THE HANDPIECE SUDDENLY OVERHEATED AND THE DENTIST FOUND A BLISTER WITH A DIAMETER OF ONE CENTIMETER ON THE PATIENT'S LIP. - THE DENTIST INTRODUCED A CLINIC TO THE PATIENT TO TREAT THE BURN INJURY.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    607978 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. EVA-Y

    Patients

    Seq Age Sex Outcome Treatment
    1 Other