BEUDAMED
    FDA Adverse Event Malfunction Summary report: N

    NSK

    MDR report key: 5986176 · Received September 29, 2016

    Report

    Report Number
    9611253-2016-00056
    Event Type
    Malfunction
    Date Received
    September 29, 2016
    Date of Event
    May 20, 2016
    Report Date
    February 27, 2017
    Manufacturer
    NAKANISHI INC.
    Product Code
    EGS
    PMA / PMN Number
    K972569
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    IL, US
    Reporter Occupation
    DENTIST

    Narratives

    Additional Manufacturer Narrative · 0

    (B)(4). EXEMPTION NUMBER E2016004.

    Description of Event or Problem · 0

    ON SEPTEMBER 5, 2016, NAKANISHI RECEIVED AN E-MAIL FROM A DISTRIBUTOR ((B)(4)) ABOUT HANDPIECE PARTS COMING OFF. DETAILS ARE AS FOLLOWS. ON AUGUST 23, 2016, (B)(4) WAS MADE AWARE BY INCOMING SERVICE REPAIR PAPERWORK THAT A HEADCAP HAD COME OFF FROM AN NSK HANDPIECE, Z95L (SERIAL NO. : (B)(4)) AND DROPPED IN A PATIENT'S MOUTH. AFTER BECOMING AWARE OF THE EVENT, (B)(4) CONTACTED THE DENTIST TO OBTAIN THE FURTHER INFORMATION. THE EVENT OCCURRED ON (B)(6) 2016. A DENTIST WAS PROVIDING A BRIDGE PREPARATION TO A PATIENT. THE HEADCAP POPPED OFF AND DROPPED IN THE PATIENT'S MOUTH, AND THE BUR WAS STUCK IN THE HEAD OF THE HANDPIECE. SINCE A DENTAL ASSISTANT SUCTIONED UP THE HEADCAP, NO INJURY OCCURRED. THE PATIENT WAS UNDER LOCAL ANESTHESIA. THERE WAS NO APPARENT MALFUNCTION OBSERVED PRIOR TO THE PROCEDURE, ACCORDING TO THE DENTIST.

    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 [C160906-14-1]. 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 (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. B) NAKANISHI MEASURED THE DIMENSIONS OF THE CARBIDE BUR AND DIAMOND BUR THAT HAD BEEN RETURNED FROM THE DISTRIBUTOR. THE DIMENSION OF THE CARBIDE BUR WAS WITHIN THE CRITERIA SPECIFIED IN THE OPERATION MANUAL, BUT THE DIAMETER OF WORKING PART OF THE DIAMOND BUR WAS LARGER THAN THE UPPER LIMIT (2.0MM) SPECIFIED IN THE OPERATION MANUAL, AS SHOWN BELOW. - DIAMETER OF WORKING PART OF THE CARBIDE BUR: 1.20MM. - DIAMETER OF WORKING PART OF THE DIAMOND BUR: 5.78MM. C) NAKANISHI THEN PERFORMED A VISUAL INSPECTION OF THE HEADCAP-HEAD THREAD PART OF THE RETURNED HANDPIECE. THERE WERE NO ABNORMALITIES SUCH AS ABRASIONS OR DETERIORATION OBSERVED IN THE INSPECTION. D) NAKANISHI OBSERVED WHETHER OR NOT THE HEADCAP OF THE RETURNED HANDPIECE WOULD LOOSEN UNDER THE FOLLOWING CONDITIONS. - TIGHTENING TORQUE: 50N?ECM/45N?ECM/35N?ECM/30N?ECM/25N?ECM/20N?ECM/15N?ECM/10N?ECM/ 5N?ECM/2N?ECM. - BUR: TEST BUR/RETURNED CARBIDE BUR/RETURNED DIAMOND BUR. (NOTE) NAKANISHI USED A SIMILAR DIAMOND BUR PRODUCED BY KOMET IN THE EVALUATION. - MOTOR ROTATION SPEED: TEST BUR (40,000RPM)/CARBIDE BUR (40,000RPM)/DIAMOND BUR (16,000RPM) - LOAD: UNDER NO-LOAD AND UNDER LOAD (SOFT TOUCH CUTTING OF PHOSPHOR BRONZE/MELAMINE PLATE). - EVALUATION PERIOD: 3 MINUTES FOR EACH EVALUATION UNDER NO-LOAD AND LOAD NAKANISHI DREW A LINE ON THE HEADCAP AND HEAD AND OBSERVED FOR OCCURRENCE OF MISALIGNMENT. THERE WAS NO HEADCAP LOOSENING OBSERVED UNDER ANY CONDITIONS DESCRIBED ABOVE IN THE EVALUATION. CONCLUSIONS REACHED BASED ON THE INVESTIGATION AND ANALYSIS RESULTS: ALTHOUGH NAKANISHI COULD NOT REPLICATE THE REPORTED EVENT, NAKANISHI CONSIDERS THE POSSIBILITY, FROM SIMILAR PHENOMENON NSK HAS EXPERIENCE IN THE PAST, THAT THE COMBINATION OF A REDUCTION IN HEADCAP TIGHTENING FORCE WITH ABNORMAL VIBRATION (E.G. BUR RUNOUT, CUTTING UNDER HIGH LOAD, ETC.) CAN RESULT IN THE REPORTED HEADCAP LOOSENING/COMING OFF. FAILURE TO FOLLOW THE INSTRUCTIONS REGARDING BURS AVAILABLE FOR USE WITH THE HANDPIECE REDUCES THE HEADCAP TIGHTENING FORCE, WHICH CONTRIBUTES TO THE HEADCAP LOOSENING/COMING OFF AFTER COMBINED WITH ABNORMAL VIBRATION. IN ORDER TO PREVENT A RECURRENCE OF THE HEADCAP LOOSENING/COMING OFF, 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 NSK AMERICA AND DIRECTED NSK AMERICA TO REMIND THE USER OF THE IMPORTANCE OF FOLLOWING INSTRUCTIONS IN THE OPERATION MANUAL.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    640567 NSK HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL EGS NAKANISHI INC. Z95L

    Patients

    Seq Age Sex Outcome Treatment
    1 29 YR Other