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U.S. Department of Health and Human Services

MAUDE Adverse Event Report: NAKANISHI INC. NSK; HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL

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NAKANISHI INC. NSK; HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL Back to Search Results
Model Number Z95L
Device Problems Overheating of Device (1437); Excessive Heating (4030)
Patient Problem Pain (1994)
Event Date 11/17/2020
Event Type  Injury  
Manufacturer Narrative
The dentist refused to provide the patient id, age, and weight.The same adverse event in this report has been reported to the fda separately by the initial importer, (b)(4).
 
Event Description
On december 17, 2020, nakanishi became aware of a handpiece overheating through a complaint input into the complaint database by a distributor (b)(4).Details are as follows: the event occurred on (b)(6) 2020.A dentist was leveling off a filling of the patient's tooth using the z95l handpiece (serial no.: (b)(4)).The patient was not under anesthesia.During the procedure, the patient reported pain and heat from the device.The dentist stopped the procedure and felt that the handpiece head was hot.The procedure was completed with a different device.Since there was no visible injury to the patient, the dentist determined that no medical attention was needed.
 
Manufacturer Narrative
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 [c201218-01].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 40,000 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.B.3) 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 into the test were as follows: test point (1): 38.3 degrees c, test point (2): 45.1 degrees c, test point (3): 34.1 degrees c, test point (4): 33.7 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 did not observe any abnormalities.Conclusions reached based on the investigation and analysis results: a) nakanishi could not identify the exact cause of the overheating of the returned device, because nakanishi was not able to replicate the temperature rise at the time of the event and did not observe any abnormalities in the visual inspection.B) in spite of the fact that nakanishi did not identify the cause, nakanishi took the following actions to be safe.B.1) nakanishi reviewed the operation manual and reconfirmed the clarity and understandability of the instructions.B.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.
 
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Brand Name
NSK
Type of Device
HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL
Manufacturer (Section D)
NAKANISHI INC.
700 shimohinata
kanuma-shi, tochigi-ken 322-8 666
JA  322-8666
MDR Report Key11159926
MDR Text Key242176571
Report Number9611253-2021-00002
Device Sequence Number1
Product Code EGS
Combination Product (y/n)N
PMA/PMN Number
K182999
Number of Events Reported1
Summary Report (Y/N)N
Report Source Manufacturer
Source Type company representative
Type of Report Initial,Followup
Report Date 02/11/2021
1 Device was Involved in the Event
1 Patient was Involved in the Event
Is this an Adverse Event Report? No
Is this a Product Problem Report? Yes
Device Operator Health Professional
Device Model NumberZ95L
Device Catalogue NumberC1034
Was Device Available for Evaluation? Device Returned to Manufacturer
Date Returned to Manufacturer01/18/2021
Initial Date Manufacturer Received 12/17/2020
Initial Date FDA Received01/13/2021
Supplement Dates Manufacturer Received01/21/2021
Supplement Dates FDA Received02/10/2021
Is This a Reprocessed and Reused Single-Use Device? No
Patient Sequence Number1
Patient Outcome(s) Other;
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