BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 9408031 · Received December 4, 2019

    Report

    Report Number
    9611253-2019-00053
    Event Type
    Injury
    Date Received
    December 4, 2019
    Date of Event
    November 11, 2019
    Report Date
    December 24, 2019
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    JA
    Reporter Occupation
    003

    Narratives

    Description of Event or Problem · 0

    ON DECEMBER 6, 2019, NAKANISHI RECEIVED DETAILED INFORMATION FROM THE DEALER ON THE EVENT, INCLUDING INFORMATION ABOUT THE PATIENT; THE DENTIST REFUSED TO PROVIDE THE PATIENT ID, AGE, AND WEIGHT. THE PROCEDURE THE DENTIST WAS PERFORMING AT THE TIME OF THE EVENT WAS FORMING THE BRIDGE CROWN OF THE PATIENT'S LOWER RIGHT JAW. THE PATIENT WAS NOT UNDER ANESTHESIA. DURING THE PROCEDURE, THE PATIENT COMPLAINED ABOUT THE HEAT FROM THE HANDPIECE, AND THE DENTIST FOUND A REDDISH BURN INJURY ON THE RIGHT CORNER OF THE PATIENT'S MOUTH. THE DENTIST COOLED THE BURNED AREA AND APPLIED STEROID OINTMENT TO THE WOUND. THE DENTIST DETERMINED THAT NO MORE MEDICAL INTERVENTION WAS NECESSARY FOR THE BURN. ACCORDING TO THE DENTIST, THERE WERE NO ABNORMALITIES OBSERVED IN THE DEVICE PRIOR TO USE.

    Additional Manufacturer Narrative · 1

    THE DENTIST DID NOT PROVIDE ANY INFORMATION ABOUT THE PATIENT WHEN NAKANISHI CONTACTED THE DENTAL OFFICE. NAKANISHI IS SCHEDULED TO VISIT THE DEALER ON (B)(6) 2019 TO REQUEST THEY OBTAIN DETAILS ABOUT THE EVENT, INCLUDING INFORMATION ABOUT THE PATIENT, FROM THE DENTIST. UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE THAT INCLUDED MEASURING THE OPERATING TEMPERATURE OF THE DEVICE [C191111-05]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: A) NAKANISHI EXAMINED THE DEVICE HISTORY RECORD AND THE REPAIR HISTORY FOR THE SUBJECT X95L DEVICE [SERIAL NO. (B)(4)]. THERE WERE NO PROBLEMS OBSERVED DURING THE MANUFACTURING OR TESTING NOTED IN THE DHR. THE REPAIR HISTORY SHOWED 5 SERVICE RECORDS SINCE THE DEVICE WAS SHIPPED. THE REPAIR DETAILS ARE AS FOLLOWS: APRIL 2013: THE CARTRIDGE, DRIVE SHAFT, AND DOG CLUTCH WERE REPLACED. APRIL 2017: THE CARTRIDGE, DRIVE SHAFT, DOG CLUTCH, AND HEADCAP WERE REPLACED. MARCH 2019: THE CARTRIDGE, DRIVE SHAFT, AND DOG CLUTCH WERE REPLACED. JUNE 2019: THE CARTRIDGE, DRIVE SHAFT, AND DOG CLUTCH WERE REPLACED. JULY 2019: THE CARTRIDGE, DRIVE SHAFT, AND DOG CLUTCH WERE REPLACED. WITH RESPECT TO THE REPAIRS IN THE ABOVE LIST, THE SERVICE RECORDS INDICATE THAT NAKANISHI PERFORMED ALL OF THE NECESSARY OPERATION CHECKS, AND CONFIRMED THAT ALL OF THE CRITERIA WERE MET. 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 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. NAKANISHI MEASURED THE TEMPERATURE RISE OF THE RETURNED HANDPIECE SET AT 200,000 MIN-1 (MOTOR REVOLUTION 40,000 MIN-1). NAKANISHI OBSERVED RISES IN TEMPERATURE AT THE TESTING POINTS AS SHOWN BELOW; HOWEVER, THE TEMPERATURES WERE NOT HIGH ENOUGH TO CAUSE A BURN INJURY. TEMPERATURE MEASUREMENTS 5 MINUTES AFTER THE START ARE AS FOLLOWS: TEST POINT (1): 34.2 DEGREES C, TEST POINT (2): 38.1 DEGREES C, TEST POINT (3): 28.4 DEGREES C, TEST POINT (4): 28.2 DEGREES C. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) OF THE ASSOCIATED DEVICE COMPONENTS WAS CONDUCTED AS FOLLOWS: NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INTERNAL PARTS. NAKANISHI OBSERVED THAT SOME OF THE INTERNAL PARTS WERE ABRADED AND DISCOLORED. NAKANISHI TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS AND KEPT THEM IN INVESTIGATION REPORT # (B)(4). 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 AND DISCOLORATION ON THE INTERNAL PARTS IN THE VISUAL INSPECTION. NAKANISHI DID NOT IDENTIFY THE CAUSE, BUT BASED ON THE FINDINGS 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 CAUSED BY INGRESS OF FOREIGN MATERIALS (ABRASIVE POWERS) INTO THE BEARING OF HANDPIECE CARTRIDGE. A LACK OF MAINTENANCE CAUSES THE ABRADED INTERNAL PARTS TO GENERATE DEBRIS (ABRASIVE POWDERS) WHICH LEADS TO THE ACCUMULATION OF DEBRIS ON THE INTERNAL PARTS. THIS CAUSES DEBRIS INGRESS INTO THE BEARING DURING ROTATION, 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 WILL REPORT THE ABOVE EVALUATION RESULTS TO THE DENTIST AND REMIND THE DENTIST OF THE IMPORTANCE OF MAINTENANCE, AS INSTRUCTED IN THE OPERATION MANUAL.

    Description of Event or Problem · 1

    ON (B)(6) 2019, NAKANISHI RECEIVED A PHONE CALL FROM A DEALER ABOUT AN NSK HANDPIECE OVERHEATING. UPON RECEIPT OF THE INFORMATION, NAKANISHI CALLED THE DENTAL OFFICE FOR FURTHER INFORMATION ABOUT THE EVENT. THE DENTIST COMMUNICATED THE FOLLOWING INFORMATION TO NAKANISHI: THE EVENT OCCURRED ON (B)(6) 2019. THE DENTIST WAS PERFORMING A DENTAL PROCEDURE USING THE X95L HANDPIECE (SERIAL NO. (B)(4)). DURING THE PROCEDURE, THE HANDPIECE OVERHEATED AND BURNED A PATIENT.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    1204646 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. X95L

    Patients

    Seq Age Sex Outcome Treatment
    1 Other