MAUDE Adverse Event Report: NAKANISHI INC. NSK; HANDPIECE, ROTARY BONE CUTTING

Model Number SGS-E2S

Device Problems Overheating of Device (1437); Temperature Problem (3022)

Patient Problems Burn(s) (1757); Injury (2348); Patient Problem/Medical Problem (2688)

Event Date 03/21/2017

Event Type  Death  

Manufacturer Narrative

(b)(4).

Event Description

On april 6, 2017, nakanishi received an e-mail from a distributor ((b)(4)) about a handpiece overheating.Details are as follows.- on (b)(6) 2017, (b)(4) was made aware of the event by an nsk sales representative.- the event occurred on (b)(6) 2017.- a dentist was performing a surgical extraction of tooth #3 on a patient using an nsk handpiece, sgs-e2s (serial no.(b)(4)).- the patient was under local anesthesia.- during the procedure, the handpiece overheated and the patient complained about a burning sensation on the corner of the outer lip.- the dentist found a superficial epidermal burn, 6mm in diameter on the skin of the lower lip inferior lateral to commissure.- the dentist applied hawaiian moon aloe vera to the patient's skin.- no follow-up was scheduled with the patient.- the patient has recovered from the burn injury.- according to the dentist, there were no abnormalities or malfunctions observed with the handpiece prior to use.

Manufacturer Narrative

On july 20, 2019, nakanishi was informed by the distributor (b)(4) that (b)(4) had taken the following actions as a part of the ifu recall activities.On december 15, 2018, (b)(4) sent the updated operation manuals that contain the detailed reprocessing method to the dental office to prevent the devices from overheating.On december 18, 2018, (b)(4) confirmed the receipt of the operation manuals by the dentist through usps certified receipt.

Manufacturer Narrative

Upon receiving the device involved in the mdr event from a distributor, nakanishi conducted a failure analysis of the returned device that included measuring the operating temperature of the device [c170407-06-1].These activities are described in more detail below.Methodology used: nakanishi examined the device history record and the repair history for the subject sgs-e2s 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.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.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 a 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 (80,000 min-1 for the handpiece), and measured the exothermic response.Nakanishi measured the temperature rise of the returned handpiece set at 80,000 min-1 (motor revolution 40,000 min-1).Nakanishi observed an abnormal temperature rise at test point (1) and (2) a few seconds after the start.Temperature measurements 30 seconds after the start are as follows: test point (1): 52.7 degrees c; test point (2): 69.9 degrees c; test point (3): 24.4 degrees c; test point (4): 27.6 degrees c.The rise in temperature was so sudden that the test was concluded 30 seconds into the planned 5 minute evaluation period.Nakanishi washed the inside of the handpiece using nakanishi pana spray plus.Nakanishi observed debris being expelled from the head of the handpiece by using a white filter to catch anything that was expelled.After cleaning and lubricating the handpiece as defined in the operation manual, nakanishi measured the temperature of the handpiece for the entire 5-minute evaluation period.Even after cleaning, nakanishi observed a quick rise in temperature, as follows.Test point (1): 54.0 degrees c; test point (2): 61.2 degrees c; test point (3): 46.1 degrees c; test point (4): 46.8 degrees c.Identification of the specific failure mode(s) and/or mechanic(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: there was significant debris on the bearings incorporated in the testing point (1) and (2).There was also corrosion and unidentified foreign materials on other inside parts.Nakanishi took photographs of all of the disassembled parts and kept them in a file.Nakanishi then replaced the soiled bearings and measured the exothermic situation yet again.There was no abnormal rise in temperature during the test period (see below).Nakanishi confirmed that the returned handpiece was operating as expected and within temperature specifications once the soiled bearings had been replaced.Test point (1): 41.0 degrees c; test point (2): 38.3 degrees c; test point (3): 37.6 degrees c; test point (4): 40.0 degrees c.Conclusions reached based on the investigation and analysis results: nakanishi identified that the cause of the overheating of the returned device was abnormal resistance during rotation caused by the soiled bearings due to the ingress of dirt into the bearing.A lack of maintenance causes the accumulation of dirt in the inside parts, which causes dirt ingress into the bearing during rotation.This 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 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.

• Brand Name: NSK
• Type of Device: HANDPIECE, ROTARY BONE CUTTING
• Manufacturer (Section D): NAKANISHI INC.; 700 shimohinata; kanuma-shi, tochigi-ken 322-8 666; JA 322-8666
• Manufacturer (Section G): NAKANISHI INC. REGISTRATION NUMBER : 9611253; mfr rpt# : 9611253-2017-00021; 700 shimohinata; kanuma-shi, tochigi-ken 322-8 666; JA 322-8666
• Manufacturer Contact: kenneth block ; 800 e campbell rd.; suite 202; richardson, TX 75081 ; 9724809554
• MDR Report Key: 6519384
• MDR Text Key: 73624633
• Report Number: 9611253-2017-00021
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: US
• PMA/PMN Number: K171155
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: company representative
• Reporter Occupation: Dentist
• Remedial Action: Recall
• Type of Report: Initial,Followup,Followup,Followup
• Report Date: 04/06/2017,08/05/2019

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 04/25/2017
• Is this an Adverse Event Report?: Yes
• Device Operator: Dentist
• Device Model Number: SGS-E2S
• Device Catalogue Number: H266
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 04/14/2017
• Is the Reporter a Health Professional?: Yes
• Was the Report Sent to FDA?: No
• Distributor Facility Aware Date: 03/27/2017
• Device Age: 1 YR
• Event Location: Other
• Date Report to Manufacturer: 04/06/2017
• Date Manufacturer Received: 07/20/2019
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 06/30/2015
• Is the Device Single Use?: No
• Is This a Reprocessed and Reused Single-Use Device?: No
• Type of Device Usage: Reuse
• Removal/Correction Number: 9611253-060818-001-R
• Patient Sequence Number: 1
• Patient Outcome(s): Other
• Patient Age: 36 YR
• Patient Weight: 64