BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 8724646 · Received June 21, 2019

    Report

    Report Number
    9611253-2019-00033
    Event Type
    Injury
    Date Received
    June 21, 2019
    Date of Event
    May 24, 2019
    Report Date
    August 2, 2019
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    SC, US
    Reporter Occupation
    DENTIST

    Narratives

    Additional Manufacturer Narrative · 0

    ACCORDING TO NAM, THE DENTIST REFUSED TO PROVIDE THE PATIENT'S WEIGHT. UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM THE DISTRIBUTOR, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE THAT INCLUDED MEASURING THE OPERATING TEMPERATURE OF THE DEVICE [C190603-03]. THESE ACTIVITIES ARE DESCRIBED IN MORE DETAIL BELOW. METHODOLOGY USED: A) NAKANISHI EXAMINED THE DEVICE HISTORY RECORD AND THE REPAIR HISTORY FOR THE SUBJECT Z95L DEVICE [SERIAL NUMBER BBG90108]. THERE WERE NO PROBLEMS OBSERVED DURING MANUFACTURING OR TESTING NOTED IN THE DHR. THERE WERE ALSO NO REPAIR HISTORY RECORDS SINCE THE DEVICE WAS SHIPPED. B) NAKANISHI CONDUCTED A VISUAL INSPECTION OF THE RETURNED DEVICE AND PERFORMED A SIMPLE MOVEMENT TEST. THERE WERE NO VISIBLE ABNORMALITIES, SUCH AS CRACKS OR DENTS, 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. C) NAKANISHI CONDUCTED TEMPERATURE TESTING OF THE RETURNED DEVICE IN THE FOLLOWING MANNER: C.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. C.2) 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. C.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 POINTS (1) AND (2) A FEW SECONDS AFTER THE START. TEMPERATURE MEASUREMENTS 40 SECONDS AFTER THE START ARE AS FOLLOWS: - TEST POINT (1): 64.1 DEGREES C - TEST POINT (2): 93.9 DEGREES C - TEST POINT (3): 46.9 DEGREES C - TEST POINT (4): 34.3 DEGREES C THE RISE IN TEMPERATURE WAS SO SUDDEN THAT THE TEST WAS CONCLUDED 40 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: - THE BEARING RETAINER (BALL RETAINING PART) ON THE REAR SIDE OF THE CARTRIDGE WAS BROKEN. - THERE WAS DEBRIS ON THE INSIDE PARTS. B) NAKANISHI TOOK PHOTOGRAPHS OF ALL OF THE DISASSEMBLED PARTS AND KEPT THEM IN INVESTIGATION REPORT #C190603-03. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: 1) NAKANISHI IDENTIFIED THAT THE CAUSE OF THE OVERHEATING OF THE RETURNED DEVICE WAS ABNORMAL RESISTANCE DURING ROTATION CAUSED BY THE BROKEN BEARING RETAINER. NAKANISHI CONSIDERS THE POSSIBILITY FROM MANY YEARS OF EXPERIENCE THAT THE CAUSE OF THE BEARING RETAINER BEING BROKEN WAS THE INGRESS OF UNDESIRABLE MATERIALS INTO THE BEARINGS. 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 THE CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. 3.2) NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO NSK AMERICA AND DIRECTED NSK AMERICA TO REMIND THE USER OF THE IMPORTANCE OF MAINTENANCE, AS INSTRUCTED IN THE OPERATION MANUAL.

    Additional Manufacturer Narrative · 0

    EXEMPTION NUMBER E2016004. (B)(4). (B)(4) TOOK THE FOLLOWING ACTIONS, BUT FURTHER INFORMATION ABOUT THE EVENT AND PATIENT WAS NOT PROVIDED. ON MAY 24, 2019, (B)(4) RECEIVED A REPORT ABOUT PATIENT INJURY FROM A COMPLAINT ON CUSTOMER PAPERWORK FOR A HANDPIECE SENT IN FOR SERVICE. THE PAPERWORK STATED, "RUN HOT - BURNT PATIENT". ON MAY 28, 2019, (B)(4) MADE A PHONE CALL TO THE DENTAL OFFICE AND SPOKE WITH THE DENTIST. THE DENTIST ADMITTED THAT THERE HAD BEEN A BURN INJURY TO A PATIENT'S LIP. SINCE THE DENTIST DID NOT HAVE SPECIFIC INFORMATION ABOUT THE EVENT, THE DENTIST WOULD HAVE TO RESEARCH FOR THE DETAILS. (B)(4) RECEIVED AN E-MAIL ADDRESS FROM THE DENTIST, AND SENT AN INFORMATION FORM FOR THE DETAILS. ON JUNE 6, 2019, (B)(4) REQUESTED THE DENTIST TO PROVIDE THE INFORMATION BY E-MAIL. ON JUNE 13, 2019, (B)(4) SENT AN E-MAIL TO THE DENTIST REQUESTING THE INFORMATION. ON JUNE 18, 2019, (B)(4) MADE A FOLLOW UP PHONE CALL AND LEFT A VOICEMAIL MESSAGE.

    Description of Event or Problem · 0

    ON (B)(6) 2019, NAKANISHI RECEIVED DETAILED INFORMATION ON THE EVENT FROM THE DISTRIBUTOR (NAM). - THE PROCEDURE THE DENTIST WAS PERFORMING AT THE TIME OF THE EVENT WAS A RESTORATIVE PROCEDURE. - THE PATIENT WAS UNDER LOCAL ANESTHESIA. - THE PATIENT HAD A BLISTER 1 CENTIMETER IN DIAMETER, WITH FIRST DEGREE BURNS RADIATING OUT APPROXIMATELY 1.5 CENTIMETERS. - THE PATIENT WAS ADMINISTERED A CHLOROHEXIDINE RINSE FOR TREATMENT. - THE DENTIST REPORTED THE INJURY IS HEALING NORMALLY AND NO FURTHER MEDICAL ATTENTION IS REQUIRED FOR TREATMENT.

    Description of Event or Problem · 0

    ON JUNE 3, 2019, NAKANISHI RECEIVED AN E-MAIL FROM A DISTRIBUTOR (B)(4) ABOUT A HANDPIECE OVERHEATING. DETAILS ARE AS FOLLOWS. THE EVENT OCCURRED AROUND (B)(6) 2019 (THE EXACT DATE IS UNKNOWN). A DENTIST WAS PERFORMING A DENTAL PROCEDURE USING THE Z95L 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
    518078 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 68 YR Other