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

Model Number SGS-E2S

Device Problems Nonstandard Device (1420); Overheating of Device (1437); Temperature Problem (3022)

Patient Problems Burn(s) (1757); Superficial (First Degree) Burn (2685)

Event Date 04/26/2021

Event Type  Injury  

Manufacturer Narrative

Despite repeated attempts, the dentist did not disclose any information about the patient to the distributor.The same adverse event in this report has been reported to the fda separately by the initial importer, nsk america corporation, under report number 1422375-2021-00012.

Event Description

On may 8, 2021, nakanishi became aware of a handpiece overheating through a complaint input into the complaint database by a distributor (nsk america).Details are as follows: the event occurred around (b)(6) 2021.(the exact date is unknown.) the dentist was performing a dental procedure using the sgs-e2s handpiece (serial (b)(4)).During the procedure, the device overheated and burned the patient.

Manufacturer Narrative

Upon receiving the device involved in the mdr event, nakanishi conducted a failure analysis of the returned device [report no.(b)(4)].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 no.(b)(6)].There were no problems observed during manufacturing or testing noted in the dhr.There were also no repair history records since the device was shipped.B) the handpiece was already disassembled when the device was returned.Therefore, nakanishi was not able to conduct temperature testing of the device.Identification of the specific failure mode(s) and/or mechanism(s) of the associated device components was conducted as follows: a) nakanishi performed a visual inspection of the disassembled handpiece and observed the following: - the bearing in the nose was extremely soiled, and the bearing retainer was broken.- the other internal parts were also soiled and discolored.B) nakanishi took photographs of all the disassembled parts and kept them in investigation report #(b)(4).Conclusions reached based on the investigation and analysis results: a) nakanishi could not replicate the temperature increase from the event, but based on the findings in the visual inspection, as well as many years of experience, nakanishi identified that the cause of the handpiece overheating was abnormal resistance during rotation due to the broken bearing retainer.Nakanishi also considers the possibility that the cause of the broken bearing retainer was ingress of undesirable material into the bearing, leading to abrasion.B) a lack of maintenance caused the accumulation of debris on the internal parts, which caused debris ingress into the bearing retainer during rotation.This contributed to the handpiece overheating.C) in order to prevent a recurrence of the handpiece overheating, nakanishi took the following actions: c.1) nakanishi reviewed the operation manual and reconfirmed the clarity and understandability of the instructions.C.2) nakanishi reported the above evaluation results to nak america and directed nsk america to remind the user of the importance of maintenance and checking of the handpiece prior to use to prevent overheating, 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
• MDR Report Key: 11910796
• MDR Text Key: 266946143
• Report Number: 9611253-2021-00035
• 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
• Report Date: 07/02/2021

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 05/31/2021
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: Yes
• Device Operator: Health Professional
• Device Model Number: SGS-E2S
• Device Catalogue Number: H266
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 05/19/2021
• Date Manufacturer Received: 06/09/2021
• 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