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

Model Number SGS-E2S

Device Problems Overheating of Device (1437); Adverse Event Without Identified Device or Use Problem (2993); Temperature Problem (3022)

Patient Problems Burn(s) (1757); Injury (2348)

Event Date 08/01/2016

Event Type  Injury  

Manufacturer Narrative

(b)(4).The information received from (b)(4) is as follows.A service history review was conducted and the handpiece had not been serviced at (b)(4).(b)(4) contacted the dental office to request additional information on august 24, 2016, august 26, 2016, and august 31, 2016.The request for additional information was not made available to (b)(4).Nakanishi is submitting two separate mdrs for this event because two patients were burned with the handpiece model sgs-e2s (serial no.(b)(4)).This mdr is related with mfr rp#:9611253-2016-00057 in describing event or problem.

Event Description

On september 5, 2016, nakanishi received an email from a distributor ((b)(4)) describing a burn to a patient.Details are as follows.On august 22, 2016, (b)(4) was made aware of unconfirmed patient burns by the incoming service repair notes.The incoming notes stated that the two patients were burned with the handpiece model sgs-e2s (serial no.(b)(4)).The event occured on (b)(6) 2016.(b)(4) contacted the dental office to obtain more information, and the (b)(4) patient information form was immediately forwarded to dental office manager to be completed.There was no response from the dental office.

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 abey0100).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 (test point (1), which was most proximal to the patient, and test points (2) through (4), which were located progressively farther toward the distal end of the device).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) 40 seconds after the start.Temperature measurements 40 seconds after the start are as follows: - test point (1): 63.6 degrees c - test point (2): 76.1 degrees c.- test point (3): 34.7 degrees c.- test point (4): 42.0 degrees c.The temperature testing was conducted for 40 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) using the same procedure described in c.1), nakanishi measured the temperature rise of the handpiece that had been cleaned using pana spray plus.Nakanishi still confirmed abnormal temperature: 81.8 degrees c at test point (2).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 nsk america and directed nsk america 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. REGISTRATION NUMBER9611253; mfr rp#:9611253-2016-00055; 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: 5985880
• MDR Text Key: 55899475
• Report Number: 9611253-2016-00055
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: US
• PMA/PMN Number: K970953
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: distributor,health profession
• Reporter Occupation: Dentist
• Remedial Action: Recall
• Type of Report: Initial,Followup,Followup
• Report Date: 09/03/2016,07/10/2018

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 09/28/2016
• 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
• Is the Reporter a Health Professional?: Yes
• Was the Report Sent to FDA?: No
• Distributor Facility Aware Date: 08/22/2016
• Device Age: 2 YR
• Event Location: Other
• Date Report to Manufacturer: 09/03/2016
• Date Manufacturer Received: 06/09/2018
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 11/20/2014
• Is the Device Single Use?: No
• Is This a Reprocessed and Reused Single-Use Device?: No
• Type of Device Usage: Reuse
• Removal/Correction Number: 9611253-060818-001-R
• Patient Sequence Number: 1
• Patient Outcome(s): Other