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

Model Number X-SG65L

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

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

Event Date 03/01/2019

Event Type  Injury  

Manufacturer Narrative

According to the distributor, the dentist refused to provide the patient's id and weight.Upon receiving the device involved in the mdr event, nakanishi conducted a failure analysis of the returned device that included measuring the operating temperature of the device [(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 x-sg65l 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 (december 2017) since the device was shipped.According to the service record, after repairing the handpiece (replacement of chuck, dog clutch, body assy and 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), without 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 tens of seconds after the start.Temperature measurements 5 minutes after the start are as follows: test point (1): 69.7 degrees c; test point (2): 54.7 degrees c; test point (3): 44.0 degrees c; test point (4): 32.5 degrees c.Identification of the specific failure mode(s) and/or mechanism(s) and the associated device components involved: nakanishi disassembled the handpiece and performed a visual inspection of the inside parts.Nakanishi observed the following phenomena: the ball bearing incorporated in the tip of the handpiece was broken.The inner race came off of the bearing.The balls in the bearing were abraded.There was also debris and corrosion on the other parts.Nakanishi took photographs of all of the disassembled parts and kept them in the investigation report # (b)(4).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 bearing due to the ingress of undesirable materials into the bearing.A lack of maintenance causes the accumulation of debris on the inside parts, which causes debris 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 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 (b)(6) 2019, nakanishi received a phone call from a distributor about an nsk handpiece overheating.The details are as follows.The event occurred on (b)(6) 2019.A dentist was extracting impacted wisdom teeth on both sides using the x-sg65l handpiece (serial no.(b)(4)).The patient was under local anesthesia.During the procedure, the dentist noticed that the color of the mucous membrane in the patient's mouth was changing to a burnt color.

• 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: kenneth block ; 800 e campbell rd.; suite 202; richardson, TX 75081 ; 9724809554
• MDR Report Key: 8449390
• MDR Text Key: 139751093
• Report Number: 9611253-2019-00017
• 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: distributor,foreign
• Reporter Occupation: Non-Healthcare Professional
• Type of Report: Initial
• Report Date: 03/25/2019

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 03/25/2019
• 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: 03/07/2019
• Date Manufacturer Received: 03/01/2019
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 01/30/2016
• 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: 30 YR