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

Model Number SGA-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); Burn, Thermal (2530); Burn, Thermal (2530); Partial thickness (Second Degree) Burn (2694); Partial thickness (Second Degree) Burn (2694)

Event Date 07/18/2016

Event Type  Injury  

Manufacturer Narrative

(b)(4).(b)(4) contacted the dentist and details are as follows: on july 29, 2016, (b)(4) contacted the dental office to inquire if assistance was needed with sending the handpiece to (b)(4).There was no response from the dental office.As of this date, (b)(4) has not received the handpiece from the dental office.

Event Description

On august 2, 2016, nakanishi received an email from a distributor ((b)(4)) describing a burnt to a patient.Details are as follows: on july 19, 2016, (b)(4) was made aware of an unconfirmed patient burn from a dentist.The dentist explained that the dentist burned a patient while removing wisdom teeth.The dentist was working on the left side.The dentist noticed a white spot on the inside cheek after the removal.The dentist claimed the handpiece was not hot to the touch.The dentist proceeded to remove the right side wisdom tooth and noticed a white spot on the patient's lip.(b)(4) contacted the dentist to obtain more information needed, and the (b)(4) patient information form was forwarded to the dentist to complete, along with a shipping label for sending the handpiece in question to (b)(4).(b)(4) received the patient information form from the dentist on july 26, 2016 and details are as follows.The dentist stated that iv sedation with local anesthesia was administered.No malfunction was observed by the dentist prior to the procedure.At the end of the procedure, there was evidence of lip and skin injury.The patient sustained lip trauma on right side and skin trauma on left side.The patient sought a dermatologist, and the patient was classified by the dermatologist as having a second-degree thermal burn.The patient was seen by dermatologist 2 days post-injury, and rx cream was prescribed along with a topical antibiotic ointment.

Manufacturer Narrative

Upon receiving the device involved in the adverse event, nakanishi conducted a failure analysis of the returned device: methodology used: 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; 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.Investigation of overheating: 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; 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; nakanishi observed an abnormal rise in temperature at test point (2) 16 seconds after the start.Temperature measurements 16 seconds after the start are as follows: test point (1): 44.6 degrees c; test point (2): 105.2 degrees c; test point (3): 30.6 degrees c; test point (4): 30.9 degrees c.The temperature testing was conducted for 16 seconds into the planned 5 minute evaluation; 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; nakanishi measured the temperature rise of the handpiece cleaned using pana spray plus the way described.Nakanishi still confirmed an abnormal temperature: 93.2 degrees at test point (2).Identification of the specific failure mode(s) and/or mechanism(s) and the associated device component(s) involved: nakanishi disassembled the handpiece and performed a visual inspection of the inside parts.Nakanishi observed that the bearings were dirty.Nakanishi also observed corrosion on a part of the spindle; nakanishi took photographs of all of the disassembled parts and kept them in a file; 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.Conclusion reached based on the investigation and analysis result: nakanishi identified that the cause of the overheating of the returned device was abnormal resistance during rotation caused by dirt in the bearings; 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; in order to prevent a recurrence of the handpiece overheating, nakanishi took the following actions: nakanishi reviewed the operation manual and reconfirmed clarity and understandability of the instructions; nakanishi reported the above evaluation results to nsk (b)(4) and directed nsk (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.On november 5, 2018, nam sent the updated operation manuals that contain the detailed reprocessing method to the dental office to prevent the devices from overheating.On november 8, 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: 5895990
• MDR Text Key: 52736346
• Report Number: 9611253-2016-00045
• 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: 08/01/2016,08/02/2019

1 Device was Involved in the Event

2 Patient was Involved in the Event

• Date FDA Received: 08/23/2016
• 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?: No
• Was the Report Sent to FDA?: No
• Distributor Facility Aware Date: 07/19/2016
• Device Age: 5 YR
• Event Location: Other
• Date Report to Manufacturer: 08/01/2016
• Date Manufacturer Received: 07/20/2019
• Is This a Reprocessed and Reused Single-Use Device?: No
• Removal/Correction Number: 9611253-060818-001-R
• Patient Sequence Number: 0
• Patient Outcome(s): Other
• Patient Age: 17 YR
• Patient Weight: 95