MAUDE Adverse Event Report: NAKANISHI, INC. NSK SGS-E2S; HANDPIECE, ROTARY BONE CUTTING

Model Number SGS-S2S

Device Problem Insufficient Information (3190)

Patient Problem Burn, Thermal (2530)

Event Date 03/06/2015

Event Type  Injury  

Event Description

On (b)(6) 2015, nsk america corporation was made aware that a pt may have been burned by a nsk handpiece.Two handpieces were sent to nsk america by dentist.The dentist was not sure which handpiece was used.The piece (sgs-e2s) serial number (b)(4) and serial number (b)(4) were received by nsk america on (b)(4) 2015.The dentist stated to nsk america that the burn was a 2nd degree burn on the left commissure of the lower lip during extraction of wisdom teeth.Pt had no permanent damage and was treated with antibacterial ointment.The injury was reported to be healing normally.This report is for serial number (b)(4) and nsk america corporation reported for serial number (b)(4) under the report #1422375-2015-00010 (mfr report # 9611253-2015-00083).Nakanishi has started the eval process of the returned products.Nakanishi will submit add'l info including results obtained through the investigation as a f/u report.

Manufacturer Narrative

Upon receipt from the dentist of the device involved in the mdr event, nakanishi conducted a failure analysis of the returned device that included an attempt to measure the temperature of the operating device.These activities are described in more detail below.Methodology used: a) nakanishi conducted a visual inspection of the returned device and performed a simple movement test.There were no visible abnormalities, such as cracks or debris, 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.B) nakanishi measured the temperature of the handpiece.Nakanishi attached a thermocouple (sensor to measure a temperature) to four testing points.Nakanishi took photographs of the configuration of the temperature measurement test.Nakanishi rotated the handpiece at 40,000 rpm which is maximum rpm for the motor that drives the handpiece without water spray and measured the exothermic situation.The temperature reached 42.8 degrees c.74.7 degrees c.30.9 degrees c and 27.4 degrees c respectively, 18 seconds after the beginning of the test.Nakanishi created charts using the data for analysis.Identification of the specific failure mode(s) and/or mechanism(s) and the associated device components involved: nakanishi disassembled the handpiece and performed a visual inspection of the inside parts.Nakanishi observed worn powder of ball bearing retainer buildup inside the head cap and the cartridge (head cap side).Nakanishi reassembled and washed the handpiece using nakanishi pana-spray per the instruction included in the user manual.Nakanishi observed dirt/debris expelled from the head of the handpiece by using a white filter to catch anything that was expelled.Nakanishi took photographs of the expelled dirt/debris.Nakanishi believes that overheating was caused by the wear of bearing retainer.The dirt/debris accumulated inside the bearing retainer increased the rear bearing load and caused excess heat generation.Conclusions reached based on the investigation and analysis results: nakanishi identified that the cause of overheating of the returned device was due to damage to the bearing retainer that was caused by accumulated dirt/debris.The damage observed caused abnormal rotational resistance, which would result in the handpiece overheating.

Manufacturer Narrative

On july 20, 2019, nakanishi was informed by the distributor (b)(4) that (b)(4) had taken the following actions as a part of the ifu recall activities.On december 13, 2018, (b)(4) sent the updated operation manuals that contain the detailed reprocessing method to the dental office to prevent the devices from overheating.On december 18, 2018, (b)(4) confirmed the receipt of the operation manuals by the dentist through usps certified receipt.

• Brand Name: NSK SGS-E2S
• 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.; 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: 4778557
• MDR Text Key: 5779739
• Report Number: 9611253-2015-00082
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: US
• PMA/PMN Number: K171155
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: Health Professional,Distributor,distributor,health prof
• Reporter Occupation: Dental Assistant
• Remedial Action: Recall
• Type of Report: Initial,Followup,Followup,Followup
• Report Date: 04/21/2015,08/02/2019

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 05/14/2015
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: No
• Device Operator: Other
• Device Model Number: SGS-S2S
• Device Catalogue Number: H266001

Device Lot Number

• Was Device Available for Evaluation?: Yes
• Date Returned to Manufacturer: 04/21/2015
• Is the Reporter a Health Professional?: No
• Was the Report Sent to FDA?: Yes
• Date Report Sent to FDA: 04/21/2015
• Distributor Facility Aware Date: 03/25/2015
• Event Location: Other
• Date Report to Manufacturer: 04/16/2015
• Date Manufacturer Received: 07/20/2019
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 08/23/2009
• Is the Device Single Use?: No
• Type of Device Usage: Reuse
• Removal/Correction Number: 9611253-060818-001-R
• Patient Sequence Number: 1
• Patient Outcome(s): Other
• Patient Age: 31 YR
• Patient Weight: 104