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

Model Number SGA-E2S

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

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

Event Date 09/22/2016

Event Type  Injury  

Manufacturer Narrative

(b)(4).The information received from (b)(4) is as follows.On october 14, 2016, the dentist forwarded to (b)(4) pictures of the patient's lip injury taken at the two week post exam, along with an invoice dated october 3, 2016 from the dental handpiece repair company.On october 14, 2016, (b)(4) conducted a service repair history review.No records of service were found.On october 21, 2016, (b)(4) received the patient information from the dentist, but the dentist did not disclose the patient's weight.

Event Description

On october 25, 2016, nakanishi received an email from a distributor (b)(4) describing a burn to a patient.Details are as follows.On october 14, 2016, (b)(4) was made aware of an unconfirmed patient burn caused by the dentist.The dentist stated the handpiece sga-e2s (serial number (b)(4) ) was repaired two weeks prior to this reported event by a dental repair service company and was returned to the dental service for repair again on october 3, 2016.The event occurred because the handpiece was extremely hot and burned a patient's lip.The event occurred on (b)(6) 2016.The dentist stated the procedure was the removal of an impacted tooth #32.The patient was administered n20102 anesthesia.No malfunction was observed by the dentist prior to use.The dentist stated no treatment was administered at the time the injury occurred.A follow up was conducted with the patient at a two week post exam and another follow up is scheduled for a five week exam.Further medical attention may be required, per doctor, depending on an evaluation by an oral surgeon and a plastic surgeon that is independently scheduled by the patient's guardian.(b)(4) contacted the dental office to obtain more information, and the nsk patient information form was immediately forwarded to the dentist to be completed.

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 sga-e2s device (serial number abc60038).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 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 rise at test point (1) 300 seconds after the start.Temperature measurements 300 seconds after the start are as follows: - test point (1): 53.2 degrees c, - test point (2): 50.2 degrees c, - test point (3): 40.6 degrees c, - test point (4): 43.4 degrees c.The temperature testing was conducted for the full 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 did not observe abnormal temperature rising during the test period.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.D.1.1) nakanishi found that the bearing used at the distal end of the handpiece was not an original nakanishi bearing.-nakanishi confirmed that the width of the c-ring, the inner ring chamfered portion, and the material of the balls were different as compared with the original nakanishi bearing.D.1.2) nakanishi observed dirt in the inside parts.D.1.3) nakanishi also observed corrosion on a part of the spindle and the gear meshing portion.D.2) nakanishi took photographs of all of the disassembled parts and kept them in a file.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 dirt/debris in the 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.

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 december 17, 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: 6091689
• MDR Text Key: 59573796
• Report Number: 9611253-2016-00065
• 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: 10/24/2016,08/05/2016

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: SGA-E2S
• Device Catalogue Number: H265001
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 10/21/2016
• Was the Report Sent to FDA?: No
• Distributor Facility Aware Date: 10/14/2016
• Device Age: 4 YR
• Event Location: Other
• Date Report to Manufacturer: 10/24/2016
• Initial Date Manufacturer Received: 10/25/2016
• Initial Date FDA Received: 11/09/2016
• Supplement Dates Manufacturer Received: Not provided; 06/09/2018; 07/20/2019
• Supplement Dates FDA Received: 04/04/2017; 07/11/2018; 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: 17 YR