MAUDE data represents reports of adverse events involving medical devices. This maude entry was filed from a distributor,foreign report with the FDA on 2020-02-20 for NSK X95L C600 manufactured by Nakanishi Inc..
[188813377]
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 [c200123-02]. These activities are described in more detail below. Methodology used: nakanishi examined the device history record and the repair history for the subject x95l device [serial number (b)(4)]. There were no problems observed during the manufacturing or testing noted in the dhr. The repair history showed 2 service records (may 2015 and october 2019) since the device was shipped. According to the service records, after repairing the handpiece (replacement of cartridge, drive shaft and dog clutch for both of the repairs), 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 into the test were as follows: test point (1): 37. 8 degrees c. Test point (2): 37. 5 degrees c. Test point (3): 28. 1 degrees c. Test point (4): 27. 6 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 of 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 the possibility that the cause of the handpiece overheating was abnormal resistance during rotation caused by ingress of foreign materials (abrasive powders) 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.
Patient Sequence No: 1, Text Type: N, H10
[188813378]
On january 29, 2020, an nsk x95l handpiece was returned from a distributor to nakanishi for repair. There was a note with the device stating that the device had overheated and burned a patient. Upon receipt of the information, nakanishi made a phone call to the dentist for further information about the event. The details nakanishi obtained from the communication are as follows: the event occurred on (b)(6) 2020. The dentist was carrying out a preparation for #6 of the patient's upper right jaw using the handpiece x95l (serial no. (b)(4)). The patient was not under anesthesia. During the procedure, the patient complained about feeling pain in the mouth and the handpiece feeling too warm. The dentist found a whitish burn 2-3 centimeters in diameter on the buccal mucous membrane. The dentist irradiated the burned area with a laser and applied oral ointment to the area. The dentist determined that no further medical attention was required for the injury. According to the dentist, there were no abnormalities observed in the device prior to use.
Patient Sequence No: 1, Text Type: D, B5
| Report Number | 9611253-2020-00004 |
| MDR Report Key | 9736331 |
| Report Source | DISTRIBUTOR,FOREIGN |
| Date Received | 2020-02-20 |
| Date of Report | 2020-02-21 |
| Date of Event | 2020-01-20 |
| Date Mfgr Received | 2020-01-29 |
| Device Manufacturer Date | 2012-06-04 |
| Date Added to Maude | 2020-02-20 |
| Event Key | 0 |
| Report Source Code | Manufacturer report |
| Manufacturer Link | Y |
| Number of Patients in Event | 0 |
| Adverse Event Flag | 3 |
| Product Problem Flag | 3 |
| Reprocessed and Reused Flag | 3 |
| Health Professional | 3 |
| Initial Report to FDA | 3 |
| Report to FDA | 3 |
| Event Location | 3 |
| Manufacturer Contact | MR KENNETH BLOCK |
| Manufacturer Street | 800 E CAMPBELL RD. SUITE 202 |
| Manufacturer City | RICHARDSON, TX |
| Manufacturer Country | US |
| Manufacturer Phone | 4809554 |
| Manufacturer G1 | NAKANISHI INC. |
| Manufacturer Street | 700 SHIMOHINATA |
| Manufacturer City | KANUMA-SHI, TOCHIGI-KEN 322-8666 |
| Manufacturer Country | JA |
| Manufacturer Postal Code | 322-8666 |
| Single Use | 3 |
| Previous Use Code | 3 |
| Event Type | 3 |
| Type of Report | 3 |
| Brand Name | NSK |
| Generic Name | HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL |
| Product Code | EGS |
| Date Received | 2020-02-20 |
| Returned To Mfg | 2020-01-29 |
| Model Number | X95L |
| Catalog Number | C600 |
| Operator | HEALTH PROFESSIONAL |
| Device Availability | R |
| Device Eval'ed by Mfgr | Y |
| Device Sequence No | 1 |
| Device Event Key | 0 |
| Manufacturer | NAKANISHI INC. |
| Manufacturer Address | 700 SHIMOHINATA KANUMA-SHI, TOCHIGI-KEN 322-8666 JA 322-8666 |
| Patient Number | Treatment | Outcome | Date |
|---|---|---|---|
| 1 | 0 | 1. Other | 2020-02-20 |