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

Model Number X-SG65L

Device Problem Overheating of Device (1437)

Patient Problem Burn(s) (1757)

Event Date 12/05/2023

Event Type  Injury  

Manufacturer Narrative

Upon receiving the device involved in the mdr event, nakanishi conducted a failure analysis of the returned device, which included measuring the operating temperature of the device [report no.C231213-01].These activities are described in more detail below.Methodology used: a) nakanishi examined the device history record and the repair history for the subject x-sg65l device (b)(6).There were no problems observed during manufacturing or testing noted in the dhr.The repair history showed 1 service record since the device was shipped.The repair details are as follows: august 2023: the chuck, bearings, dog clutch, body, slider, pin, chuck retainer, spring and spindle were replaced.With respect to the repairs in the above list, the service record indicate that nakanishi performed all of the necessary operation checks and confirmed that all of the criteria were met.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 40,000min-1, which is the maximum rpm for the motor that drives the handpiece (40,000min-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 40,000min-1 (motor revolution 40,000min-1).Nakanishi observed an abnormal temperature rise at the test point (1) 1 minute into the test.Temperature measurements about 4 minutes 30 seconds after the start of the test were as follows: test point (1): 64.2 degrees c.Test point (2): 54.7 degrees c.Test point (3): 45.2 degrees c.Test point (4): 37.0 degrees c.Identification of the specific failure mode(s) and/or mechanism(s) of the associated device components was conducted as follows: a) nakanishi disassembled the handpiece and performed a visual inspection of the internal parts.Nakanishi observed the following: the bearing was soiled, discolored, and abraded.The inner and outer races, the bearing retainer and the bearing balls were discolored and metal-stripped.The chuck, body and spindle were soiled and discolored.B) nakanishi took photographs of all the disassembled parts and kept them in the investigation report no.(b)(4).Conclusions reached based on the investigation and analysis results: a) nakanishi determined that the cause of the handpiece overheating was abnormal resistance during rotation due to the damaged bearing.Nakanishi considers the possibility from many years of experience that the cause of the damaged bearing was the ingress of undesirable materials into the bearing, leading to abrasion.B) a lack of maintenance caused the accumulation of debris on the internal parts, which caused debris ingress into the bearing during rotation.This contributed to the handpiece overheating.C) in order to prevent a recurrence of the handpiece overheating, nakanishi took the following actions: c.1) nakanishi reviewed the operation manual and reconfirmed the clarity and understandability of the instructions.C.2) 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 december 12, 2023, an nsk x-sg65l handpiece was returned from an oem 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 oem for further information about the event including information about the patient.The details nakanishi obtained are as follows: the event occurred on december 5, 2023.The dentist was extracting a completely impacted wisdom tooth of a patient using the x-sg65l handpiece (serial no.(b)(6).The patient was under general anesthesia.During the procedure, the handpiece overheated, and the patient received a 1st-degree burn injury about 5x4mm to their left lingual margin and about 40 to 50mm extending from their buccal mucosa to their lip.The dentist felt that water was not running from a motor as usual twice during the procedure, but the water flow returned to normal immediately.A dermatologist in the same hospital prescribed a steroid ointment for the patient the next day.The patient has had a follow-up visit with the dentist and the injury was reported to have healed normally without need for any additional medical treatment.

• 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, IL 60192 ; 2245128921
• MDR Report Key: 18361440
• MDR Text Key: 330932086
• Report Number: 9611253-2023-00070
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: JA
• PMA/PMN Number: K970953
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: Other,Foreign
• Reporter Occupation: Non-Healthcare Professional
• Type of Report: Initial
• Report Date: 12/20/2023

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 12/19/2023
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: Yes
• Device Operator: Health Professional
• Device Model Number: X-SG65L
• Device Catalogue Number: H1009
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 12/13/2023
• Date Manufacturer Received: 12/12/2023
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 09/21/2022
• Is the Device Single Use?: No
• Is This a Reprocessed and Reused Single-Use Device?: No
• Type of Device Usage: Reuse
• Patient Sequence Number: 1
• Patient Outcome(s): Other
• Patient Age: 50 YR
• Patient Sex: Male
• Patient Weight: 65 KG
• Patient Ethnicity: Non Hispanic
• Patient Race: Asian