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

Model Number Z-SG45L

Device Problem Overheating of Device (1437)

Patient Problems Burn(s) (1757); Superficial (First Degree) Burn (2685)

Event Date 03/28/2022

Event Type  Injury  

Event Description

On april 1, 2022, nakanishi received an e-mail from a distributor about an nsk handpiece overheating.The details are as follows: the event occurred on (b)(6), 2022.A dentist was performing a dental procedure on a patient using the z-sg45l handpiece (serial no.(b)(4)).During the procedure, the handpiece overheated and the patient received an burn injury to their buccal mucosa.

Manufacturer Narrative

Nakanishi is still trying to obtain further information about the patient.This event occurred in japan, but similar products are marketed in the us under k211584.

Event Description

On april 19, 2022, nakanishi obtained the following information about the event during a visit to the dentist.The procedure the dentist was performing at the time of the event was a 3rd molar extraction.

Manufacturer Narrative

The dentist refused to provide the patient's weight.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.(b)(4)].These activities are described in more detail below.Methodology used: a) nakanishi examined the device history record and the repair history for the subject z-sg45l 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 (120,000 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 120,000 min-1 (motor revolution 40,000 min-1).Nakanishi observed an abnormal temperature rise at all the test points a few seconds into the test.Temperature measurements 120 seconds after the start of the test were as follows: test point (1): 87.4 degrees c, test point (2): 85.8 degrees c, test point (3): 63.5 degrees c, test point (4): 60.1 degrees c.The increase in temperature was so sudden that the test was concluded 120 seconds into the planned 5-minute evaluation period.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 retainers (ball retaining part) in the cartridge and drive gear were broken.The headcap and internal gear were discolored and soiled; b) 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: a) nakanishi determined that the cause of the overheating of the returned device was frictional resistance caused by the broken bearing retainers of the cartridge and drive gear.B) nakanishi considers the possibility from many years of experience that the cause of the broken bearing retainers was the ingress of undesirable materials into the bearing.C) 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.D) in order to prevent a recurrence of the handpiece overheating, nakanishi took the following actions: d.1) nakanishi reviewed the operation manual and reconfirmed the clarity and understandability of the instructions.D.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.

• 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: 14191799
• MDR Text Key: 289953424
• Report Number: 9611253-2022-00023
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: JA
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: Foreign,Distributor
• Reporter Occupation: Non-Healthcare Professional
• Type of Report: Initial,Followup
• Report Date: 04/28/2022

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: Yes
• Device Operator: Health Professional
• Device Model Number: Z-SG45L
• Device Catalogue Number: C1107
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 04/05/2022
• Initial Date Manufacturer Received: 04/01/2022
• Initial Date FDA Received: 04/25/2022
• Supplement Dates Manufacturer Received: 04/12/2022
• Supplement Dates FDA Received: 04/28/2022
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 04/11/2014
• 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: 15 YR
• Patient Sex: Male
• Patient Ethnicity: Non Hispanic
• Patient Race: Asian