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

Model Number SGS-ES

Device Problem Overheating of Device (1437)

Patient Problem Burn(s) (1757)

Event Date 12/27/2021

Event Type  Injury  

Manufacturer Narrative

Upon receiving the device involved in the mdr event from the dealer, nakanishi conducted a failure analysis of the returned device, which included measuring the operating temperature of the device [report no.(b)(4)].These activities are described in more detail below.Methodology used: nakanishi examined the device history record and the repair history for the subject sgs-es device [serial number (b)(4)].There were no problems observed during the manufacturing or testing noted in the dhr.The repair history showed 1 service record ((b)(6) 2021) since the device was shipped.According to the service record, after repairing the handpiece (replacement of bur pusher retainer, ball bearing, and spacer bearing), 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 (40,000 min-1 for the handpiece), with no water spray, and measured the exothermic response.Nakanishi measured the temperature rise of the returned handpiece set at 40,000 min-1 (motor revolution 40,000 min-1).Nakanishi observed an abnormal temperature rise at test points (1) and (2) a few seconds into the test.Temperature measurements 5 minutes after the start of the test were as follows: test point (1): 56.9 degrees c; test point (2): 51.6 degrees c; test point (3): 47.9 degrees c; test point (4): 46.4 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 the internal parts, such as ball bearing, bearing retainer, and spindle were soiled.Nakanishi took photographs of all the disassembled parts and kept them in investigation report no.(b)(4).Conclusions reached based on the investigation and analysis results: nakanishi determined that the cause of the overheating of the returned device was abnormal resistance during rotation due to the soiled internal parts.A lack of maintenance caused the accumulation of debris on the internal parts, which contributed 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 the clarity and understandability of the instructions.Nakanishi reported the above evaluation results to the dentist, and reminded the dentist of the importance of maintenance and checking of the handpiece prior to use to prevent overheating, as instructed in the operation manual.

Event Description

On january 12, 2022, an nsk sgs-es 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.The details are as follows: the event occurred on (b)(6) 2021.The dentist was extracting tooth #8 of the patient's lower right jaw using the sgs-es handpiece (serial no.(b)(4)).The patient was under general anesthesia.About 2 minutes after the start of the procedure, the dentist became aware of the handpiece feeling too warm and found a burn injury 9mm x 5mm on the patient's upper right lip.The dentist determined that no medical attention was required for the injury.

• 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.; 700 shimohinata; kanuma-shi, tochigi-ken 322-8 666; JA 322-8666
• Manufacturer Contact: sean kaufman ; 1800 global parkway; hoffman estates, IN 60192 ; 2245128921
• MDR Report Key: 13447932
• MDR Text Key: 289503702
• Report Number: 9611253-2022-00001
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: JA
• PMA/PMN Number: K171155
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: Other,Foreign
• Reporter Occupation: Non-Healthcare Professional
• Remedial Action: Recall
• Type of Report: Initial
• Report Date: 02/04/2022

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 02/03/2022
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: Yes
• Device Operator: Health Professional
• Device Model Number: SGS-ES
• Device Catalogue Number: H264
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 01/12/2022
• Date Manufacturer Received: 01/12/2022
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 12/09/2013
• 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: 22 YR
• Patient Sex: Male
• Patient Weight: 55 KG
• Patient Ethnicity: Non Hispanic
• Patient Race: Asian