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

Model Number X-SG65

Device Problem Overheating of Device (1437)

Patient Problem Burn(s) (1757)

Event Date 06/12/2023

Event Type  Injury  

Manufacturer Narrative

Nakanishi is still trying to obtain information about the event, including information about the patient.

Event Description

On july 19, 2023, nakanishi received an email from a distributor (nsk united kingdom) about a nsk handpiece overheating.The details are as follows: the event occurred around (b)(6), 2023.(the exact date is unknown).The dentist was performing a dental procedure on a patient using the x-sg65 (serial no.(b)(6)).During the procedure, the handpiece overheated, and the patient was burned quite badly.

Manufacturer Narrative

On (b)(6), 2023, nakanishi received an email from the distributor (nsk united kingdom) stating that the dentist refused to provide any further information about the event, including information about the patient.Upon receiving the device involved in the mdr event from the distributor, nakanishi conducted a failure analysis of the returned device, which included measuring the operating temperature of the device [report no.C230720-01].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-sg65 device [02120159].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) and (3)).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) approximately 2 minutes into the test.Temperature measurements about 5 minutes after the start of the test were as follows: - test point (1): 56.6 degrees c - test point (2): 45.7 degrees c - test point (3): 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 bearing balls were deformed and metal stripped.- the other internal parts such as chuck, spindle and body were soiled and discolored.B) nakanishi took photographs of all the disassembled parts and kept them in the investigation report no.C230720-01.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 broken bearing.Nakanishi considers the possibility from many years of experience that the cause of the broken 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 distributor and directed the distributor 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: 17447519
• MDR Text Key: 320289002
• Report Number: 9611253-2023-00050
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: UK
• PMA/PMN Number: K970953
• 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: 09/14/2023

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 08/02/2023
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: Yes
• Device Operator: Health Professional
• Device Model Number: X-SG65
• Device Catalogue Number: H1038
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Manufacturer Received: 08/22/2023
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 02/19/2021
• 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