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); Patient Problem/Medical Problem (2688)

Event Date 09/20/2016

Event Type  Injury  

Manufacturer Narrative

(b)(4).(b)(4) took the following actions for more information about the event, however, the detailed information was not provided.- on (b)(6) 2016, right after becoming aware of the event, (b)(4) contacted the dental office, but the office manager was not available at the time to take the call.(b)(4) left a voice mail message with a request for a return call.The office manager returned the call to (b)(4) and refused to provide the details from a place of the office manager.The assistant and the dentist was not in the office to provide the information.The manager requested (b)(4) to email the information request form (qa-011) to the office and promised to complete and send back the form immediately.(b)(4) sent the information form as requested.No response was returned from the dental office.- on october 3, 2016, (b)(4) sent a follow-up email to the office manager to ask if the email and the request form were received and if any assistance was needed.(b)(4) received no response.- on october 5, 2016, (b)(4) made a phone call and spoke with the office manager.The manager promised again that the dental office would forward the information as soon as possible.(b)(4) received no response.- on october 11, 2016, (b)(4) left a voice mail message inquiring about the requested paperwork, but (b)(4) did not receive any response.- october 11, 2016, (b)(4) called and left a voice mail message.In addition, (b)(4) sent an email to follow up to the message.No response was returned.Despite all the above efforts, (b)(4) could not obtain the further information including the patient information.

Event Description

On october 13, 2016, nakanishi received an e-mail from a distributor ((b)(4)) about handpiece overheating.Details are as follows.- on september 30, 2016, (b)(4) was made aware of the event by incoming service repair paperwork.- the event occurred on (b)(6) 2016.- an nsk handpiece, sgs-e2s (serial no.: (b)(4)) overheated and burned a patient's lip.

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 temperature of the operating device [c161014-11-1].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-e2s 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), and measured the exothermic situation.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 (2) 30 seconds after the start.Temperature measurements 30 seconds after the start are as follows: - test point (1): 48.7 degrees c - test point (2): 73.6 degrees c - test point (3): 30.7 degrees c - test point (4): 40.4 degrees c the rise in temperature was so sudden that the test was ended only 30 seconds into the planned 5 minute evaluation period.D) nakanishi washed the inside of the handpiece using nakanishi pana spray plus.Nakanishi observed dirt 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.Even after cleaning, nakanishi still observed a quick rise in temperature, as follows.- test point (1): 43.0 degrees c - test point (2): 66.1 degrees c - test point (3): 23.2 degrees c - test point (4): 33.6 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: - dirt on the bearing incorporated in test point (1).- the bearing incorporated in test point (2) was completely broken and the inner race was only seen in the bearing.- dirt and abrasions in the inside parts.B) nakanishi took photographs of all of the disassembled parts and kept them in a file.C) nakanishi then replaced the broken bearings and measured the exothermic situation yet again.There was no abnormal rise in temperature during the test period (see below).Nakanishi confirmed that the returned handpiece was operating as expected and within temperature specifications once the damaged bearings had been replaced.- test point (1): 43.7 degrees c - test point (2): 40.0 degrees c - test point (3): 37.1 degrees c - test point (4): 39.8 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 broken/worn bearings due to the ingress of dirt into the bearings.2) a lack of maintenance causes the accumulation of dirt in the inside parts, which causes dirt ingress into the bearing during rotation, leading to the broken/worn bearings.This contributes to the handpiece overheating.3) in order to prevent a recurrence of the handpiece overheating, nakanishi took the following actions: 3.1) nakanishi reviewed the operation manual and reconfirmed clarity and understandability of the instructions.3.2) 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.

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.On december 13, 2018, nam sent the updated operation manuals that contain the detailed reprocessing method to the dental office to prevent the devices from overheating.On december 17, 2018, nam confirmed the receipt of the operation manuals by the dentist through usps certified receipt.

• 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: 6069928
• MDR Text Key: 58934309
• Report Number: 9611253-2016-00063
• 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,Followup
• Report Date: 08/02/2019

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: H185
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 10/19/2016
• Was the Report Sent to FDA?: No
• Distributor Facility Aware Date: 09/30/2016
• Device Age: 2 YR
• Event Location: Other
• Initial Date Manufacturer Received: 10/13/2016
• Initial Date FDA Received: 11/01/2016
• Supplement Dates Manufacturer Received: Not provided; 06/09/2018; 07/20/2019
• Supplement Dates FDA Received: 02/23/2017; 07/12/2018; 08/02/2019
• Removal/Correction Number: 9611253-060818-001-R
• Patient Sequence Number: 1
• Patient Outcome(s): Other