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

Model Number SGS-E2S

Device Problems Nonstandard Device (1420); Overheating of Device (1437); Temperature Problem (3022)

Patient Problems Burn(s) (1757); Injury (2348); Superficial (First Degree) Burn (2685); Patient Problem/Medical Problem (2688)

Event Date 07/16/2018

Event Type  Injury  

Manufacturer Narrative

(b)(4).

Event Description

On (b)(6) 2018, nakanishi received an e-mail from a distributor (nsk america) about a handpiece overheating.Details are as follows.The event occurred on (b)(6) 2018.A dentist was performing a wisdom tooth extraction on the lower right quadrant using the sgs-e2s handpiece (serial no.: (b)(4)).When splitting the tooth in half, the dentist noticed a white mark inside of the patient's lower right lip, which was a first degree burn.According to the dentist, there were no abnormalities of the handpiece observed prior to use.The dentist immediately applied ice to the burn and continued the dental procedure.After the procedure was completed, the dentist applied ice again and administered hydrocortisone cream to the injury.The patient had a follow up visit on july 18, 2018 and was healing normally.No further medical intervention is required to treat the injury.

Manufacturer Narrative

On july 20, 2019, nakanishi was informed by the distributor ((b)(4)) that (b)(4) had taken the following actions as a part of the ifu recall activities.On december 15, 2018, (b)(4) sent the updated operation manuals that contain the detailed reprocessing method to the dental office to prevent the devices from overheating.On december 18, 2018, (b)(4) confirmed the receipt of the operation manuals by the dentist through (b)(6) certified receipt.

Manufacturer Narrative

Upon receiving the device involved in the mdr event from a distributor, nakanishi conducted a failure analysis of the returned device that included measuring the operating temperature of the device [c180809-01].These activities are described in more detail below.Methodology used: a) nakanishi examined the device history record and the repair history for the subject sgs-e2g device [serial number (b)(4)].There were no problems observed during the manufacturing or testing noted in the dhr.There were also no repair history records since the device was shipped.B) nakanishi conducted a visual inspection of the returned device and performed a simple movement test.There were no visible abnormalities, such as cracks or dents, on the outside of the handpiece.Nakanishi then set a test bur in the handpiece and rotated it by hand.Nakanishi observed that the bur did not rotate smoothly.C) nakanishi conducted temperature testing of the returned device in the following manner: c.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.C.2) nakanishi attached a thermocouple (sensor to measure a 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 (80,000 min-1 for the handpiece), with water spray, and measured the exothermic response.C.3) nakanishi measured the temperature rise of the returned handpiece set at 80,000 min-1 (motor revolution 40,000 min-1).Nakanishi observed an abnormal temperature rise at test point (1) and (2) a few seconds after the start.Temperature measurements 37 seconds after the start are as follows: - test point (1): 59.1 degrees c - test point (2): 74.0 degrees c - test point (3): 27.3 degrees c - test point (4): 29.6 degrees c the rise in temperature was so sudden that the test was concluded 37 seconds into the planned 5 minute evaluation period.D) nakanishi cleaned the inside of the handpiece using nakanishi pana spray plus.Nakanishi observed debris being expelled from the head of the handpiece by using a white filter to catch anything that was expelled.E) after cleaning and lubricating the handpiece as defined in the operation manual, nakanishi measured the temperature of the handpiece for the entire 5-minute evaluation period.Even after cleaning, nakanishi observed a quick rise in temperature, as follows.- test point (1): 68.1 degrees c - test point (2): 71.9 degrees c - test point (3): 30.0 degrees c - test point (4): 34.1 degrees c identification of the specific failure mode(s) and/or mechanism(s) and the associated device components involved: a) nakanishi disassembled the handpiece and performed a visual inspection of the inside parts.Nakanishi observed the following phenomena: - there was massive debris on the bearing incorporated in the test point (1).- the bearing incorporated in the test point (2) was broken.- there was debris and corrosion on the other parts.B) nakanishi took photographs of all of the disassembled parts and kept them in the investigation report #c180809-01.C) nakanishi then replaced the broken bearings with new bearings and measured the exothermic situation yet again.There was no abnormal rise in temperature during the 300-second-test period (see below).Nakanishi confirmed that the returned handpiece was operating as expected and within temperature specifications once the broken bearings had been replaced.- test point (1): 35.5 degrees c - test point (2): 36.2 degrees c - test point (3): 38.8 degrees c - test point (4): 43.8 degrees c conclusions reached based on the investigation and analysis results: 1) nakanishi identified that the cause of the overheating of the returned device was abnormal resistance during rotation caused by the corroded/broken bearings due to the ingress of undesirable materials into the bearings.2) 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.3) nakanishi shipped the updated operation manuals that contain detailed reprocessing methods to nsk america.Nsk america will distribute the updated manuals to the sub-distributors and users including the complainant to convey the detailed reprocessing methods to prevent a recurrence of the handpiece overheating.

• 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
• MDR Report Key: 7837011
• MDR Text Key: 118933912
• Report Number: 9611253-2018-00038
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• PMA/PMN Number: K171155
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: company representative
• Remedial Action: Recall
• Type of Report: Initial,Followup,Followup
• Report Date: 08/09/2018,08/05/2019

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: SGS-E2S
• Device Catalogue Number: H266
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 08/21/2018
• Was the Report Sent to FDA?: No
• Distributor Facility Aware Date: 07/27/2018
• Device Age: 3 YR
• Event Location: Outpatient Treatment Facility
• Date Report to Manufacturer: 08/09/2018
• Initial Date Manufacturer Received: 08/09/2018
• Initial Date FDA Received: 08/31/2018
• Supplement Dates Manufacturer Received: 09/19/2018; 07/20/2019
• Supplement Dates FDA Received: 10/15/2018; 08/04/2019
• Is This a Reprocessed and Reused Single-Use Device?: No
• Removal/Correction Number: 9611253-060818-001-R
• Patient Sequence Number: 1
• Patient Outcome(s): Other
• Patient Age: 21 YR
• Patient Weight: 54