BEUDAMED
    FDA Adverse Event Injury Summary report: N

    NSK

    MDR report key: 21088339 · Received January 6, 2025

    Report

    Report Number
    9611253-2025-00002
    Event Type
    Injury
    Date Received
    January 6, 2025
    Report Date
    March 19, 2025
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K182999
    Adverse Event
    Yes
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    OK, US
    Reporter Occupation
    OTHER HEALTH CARE PROFESSIONAL
    Health Professional
    Yes

    Narratives

    Additional Manufacturer Narrative · 0

    THE DENTIST WAS NOT ABLE TO PROVIDE ANY INFORMATION ON THE DATE OF THE INCIDENT OR PATIENT INFORMATION.

    Additional Manufacturer Narrative · 0

    UPON RECEIVING THE DEVICE INVOLVED IN THE MDR EVENT FROM THE DISTRIBUTOR, NAKANISHI CONDUCTED A FAILURE ANALYSIS OF THE RETURNED DEVICE, WHICH INCLUDED MEASURING THE OPERATING TEMPERATURE OF THE DEVICE [REPORT NO. C241214-01]. 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 NO. (B)(6)]. 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 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 TEMPERATURE) TO EACH OF THE TESTING POINTS. NAKANISHI ROTATED THE DEVICE'S MOTOR AT 40,000MIN-1, WHICH IS THE MAXIMUM RPM FOR THE MOTOR THAT DRIVES THE HANDPIECE (200,000MIN-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 200,000MIN-1 (MOTOR REVOLUTION 40,000MIN-1). NAKANISHI OBSERVED AN ABNORMAL TEMPERATURE RISE AT THE TEST POINT (2) ABOUT 30 SECONDS INTO THE TEST. TEMPERATURE MEASUREMENTS ABOUT 30 SECONDS AFTER THE START OF THE TEST WERE AS FOLLOWS: TEST POINT (1): 39.6 DEGREES C. TEST POINT (2): 55.2 DEGREES C. TEST POINT (3): 35.3 DEGREES C. TEST POINT (4): 35.2 DEGREES C. IDENTIFICATION OF THE SPECIFIC FAILURE MODE(S) AND/OR MECHANISM(S) OF THE ASSOCIATED DEVICE COMPONENTS WAS CONDUCTED AS FOLLOWS: A) NAKANISHI DISASSEMBLED THE HANDPIECE AND PERFORMED A VISUAL INSPECTION OF THE INTERNAL PARTS. NAKANISHI OBSERVED THE FOLLOWING: THE BALL BEARING ON THE REAR SIDE OF THE CARTRIDGE WAS ABRADED AND SOILED. THE INTERNAL GEARS WERE SOILED. B) NAKANISHI TOOK PHOTOGRAPHS OF ALL THE DISASSEMBLED PARTS AND KEPT THEM IN THE INVESTIGATION REPORT NO. (B)(4). CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: A) NAKANISHI IDENTIFIED THAT THE CAUSE OF THE HANDPIECE OVERHEATING WAS ABNORMAL RESISTANCE DURING ROTATION DUE TO THE SOILED INTERNAL PARTS. NAKANISHI CONSIDERS THE POSSIBILITY FROM MANY YEARS OF EXPERIENCE THAT THE CAUSE OF THE SOILED INTERNAL PARTS WAS THE INGRESS OF UNDESIRABLE MATERIALS INTO THE HANDPIECE, LEADING TO ABRASION OF THE INTERNAL PARTS. B) A LACK OF MAINTENANCE CAUSED THE ACCUMULATION OF DEBRIS ON THE INTERNAL PARTS, WHICH CAUSED DEBRIS INGRESS INTO THE INTERNAL PARTS DURING ROTATION. THIS CONTRIBUTED TO THE HANDPIECE OVERHEATING. C) IN ORDER TO PREVENT A RECURRENCE OF THE HANDPIECE OVERHEATING, NAKANISHI TOOK THE FOLLOWING ACTIONS: C.1) NAKANISHI REVIEWED THE OPERATION MANUAL AND RECONFIRMED THE CLARITY AND UNDERSTANDABILITY OF THE INSTRUCTIONS. C.2) NAKANISHI REPORTED THE ABOVE EVALUATION RESULTS TO THE DISTRIBUTOR AND DIRECTED THE DISTRIBUTOR TO REMIND THE USER OF THE IMPORTANCE OF MAINTENANCE AS INSTRUCTED IN THE OPERATION MANUAL.

    Description of Event or Problem · 0

    ON DECEMBER 14, 2024, NAKANISHI BECAME AWARE OF A HANDPIECE OVERHEATING THROUGH A COMPLAINT INPUT INTO THE COMPLAINT DATABASE BY A DISTRIBUTOR (NSK AMERICA). DETAILS ARE AS FOLLOWS: - THE EVENT OCCURRED AROUND (B)(6) 2024. (THE EXACT DATE IS UNKNOWN.) - THE DENTIST WAS PERFORMING A DENTAL PROCEDURE ON A PATIENT USING THE Z95L HANDPIECE (SERIAL NO. (B)(6)) - DURING THE PROCEDURE, THE HANDPIECE OVERHEATED, AND THE PATIENT RECEIVED A MINOR THERMAL BURN INJURY TO THE INSIDE OF THEIR CHEEK. - THE DENTIST HAS HAD NO REPORTS OF ISSUES RESULTING FROM THE BURN INJURY BY ANY OF THEIR PATIENTS, SO THEY ARE BELIEVED TO HAVE HEALED NORMALLY WITHOUT NEED FOR ADDITIONAL MEDICAL TREATMENT.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    381647 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 NA Unknown Other