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

Model Number SGS-E2S

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

Patient Problems Burn(s) (1757); Injury (2348); Superficial (First Degree) Burn (2685); Partial thickness (Second Degree) Burn (2694)

Event Date 08/03/2016

Event Type  Injury  

Manufacturer Narrative

(b)(4).The information received from (b)(4) is as follows: the handpiece was sent in to (b)(4).The handpiece arrived at (b)(4) on august 10, 2016.There were no incoming comments indicating patient involvement.Repair history review was conducted on the handpiece sgs-e2s (serial number (b)(4)).The handpiece was at (b)(4) for repair on may 10, 2016.An evaluation of the repair records found heavy amounts of debris and corrosion throughout the internal parts.On august 12, 2016, (b)(4) contacted the dental office to request additional patient information.The request for additional information was not made available to (b)(4).The dental office would not offer any further information in written or verbal communication.

Event Description

On august 15, 2016, nakanishi received an email from a distributor ((b)(4)) describing a burn to a patient.Details are as follows: on august 10, 2016, (b)(4) was made aware of an unconfirmed patient burn by (b)(4) sales representative.The dentist stated that the handpiece had burnt a patient.(b)(4) forwarded the (b)(4) patient information form to the dentist to supply information on the experience.(b)(4) received the patient information form from the dentist on august 12, 2016 by email and details are as follows.The dentist stated that the burn was on the lip.The patient received a 1st and 2nd degree burn.

Manufacturer Narrative

Upon receiving the device involved in the adverse event, nakanishi conducted a failure analysis of the returned device: methodology used: a) nakanishi examined the device history record for the subject sgs-e2s device (serial number (b)(4)).There were no problems observed during the manufacturing or testing noted in the dhr.B) nakanishi conducted a visual inspection of the returned device and performed a simple movement test.- nakanishi set a test bur in the handpiece and rotated it by hand.Nakanishi observed a rotational resistance.- nakanishi did not observe any damage on the exterior.C) investigation of overheating: c.1) temperature sensors were first attached to the exterior of the device at various test points (i.E.Most proximal to the patient, testing point (1), and along points further toward the distal end of the device, testing points (2) through (4)).The test was set up 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 temperature) to each point.Nakanishi rotated the 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), and measured the exothermic situation.C.3) nakanishi observed abnormal temperature rises at test points (1) and (2) 36 seconds after the start.Temperature measurements 36 seconds after the start are as follows: - test point (1): 59.2 degrees c.- test point (2): 90.2 degrees c.- test point (3): 30.2 degrees c.- test point (4): 39.9 degrees c.The temperature testing was conducted for 36 seconds into the planned 5 minute evaluation.C.4) nakanishi washed the inside of the handpiece using nakanishi pana spray plus, as defined in the operation manual.Nakanishi observed dirt/debris being expelled from the head of the handpiece by using a white filter to catch anything that was expelled.C.5) nakanishi measured the temperature rise of the handpiece cleaned using pana spray plus the way described in c.1) and c.2).Nakanishi still confirmed abnormal temperatures: 64.5 degrees c and 80.1 degrees c at test points (1) and (2) respectively.D) identification of the specific failure mode(s) and/or mechanism(s) and the associated device component(s) involved: d.1) nakanishi disassembled the handpiece and performed a visual inspection of the inside parts.Nakanishi observed that the bearings were broken and dirty.D.2) nakanishi took photographs of all of the disassembled parts and kept them in a file.D.3) nakanishi then replaced the bearings and measured the exothermic situation yet again.There was no abnormal rise in temperature during the test period.Nakanishi confirmed that the returned handpiece was operating as expected and within temperature specifications once the damaged bearings had been replaced.E) conclusion reached based on the investigation and analysis result: e.1) nakanishi identified that the cause of the overheating of the returned device was abnormal resistance during rotation caused by the broken bearings.E.2) a lack of maintenance causes the accumulation of dirt (abrasive powders/foreign materials) in the inside parts, which causes dirt/debris ingress into the bearing during rotation.This contributes to the handpiece overheating.E.3) in order to prevent a recurrence of the handpiece overheating, nakanishi took the following actions: e.3.1) nakanishi reviewed the operation manual and reconfirmed clarity and understandability of the instructions.E.3.2) nakanishi reported the above evaluation results to (b)(4) and directed (b)(4) to remind the user of the importance of maintenance, as instructed in the operation manual.

Manufacturer Narrative

On july 20, 2019, nakanishi was informed by the distributor (nam) that nam had taken the following actions as a part of the ifu recall activities.In november 2018 (exact date unknown), the distributor sent the updated operation manuals that contain the detailed reprocessing method, which had been provided by nam earlier, to the dental office to prevent the devices from overheating.On november 27, 2018, nam confirmed the receipt of the operation manuals through the activity sheet mailed by the dentist.

• 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: 5914891
• MDR Text Key: 53567382
• Report Number: 9611253-2016-00048
• 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: distributor,health profession
• Remedial Action: Recall
• Type of Report: Initial,Followup,Followup,Followup
• Report Date: 08/15/2016,08/05/2019

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?: No
• Device Operator: Dentist
• Device Model Number: SGS-E2S
• Device Catalogue Number: H266001
• Was Device Available for Evaluation?: Yes
• Was the Report Sent to FDA?: No
• Device Age: 3 YR
• Event Location: Other
• Date Report to Manufacturer: 08/15/2016
• Initial Date Manufacturer Received: 08/15/2016
• Initial Date FDA Received: 08/30/2016
• Supplement Dates Manufacturer Received: Not provided; 06/09/2018; 07/20/2019
• Supplement Dates FDA Received: 12/14/2016; 07/12/2018; 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: 19 YR