MAUDE Adverse Event Report: NAKANISHI INC. NSK; HANDPIECE, AIR-POWERED, DENTAL

Model Number M600LG

Device Problems Detachment Of Device Component (1104); Disassembly (1168); Mechanical Problem (1384); Detachment of Device or Device Component (2907)

Patient Problem Foreign Body In Patient (2687)

Event Date 12/05/2016

Event Type  Injury  

Manufacturer Narrative

Nakanishi has not obtained any patient information as of this report.

Event Description

On december 31, 2016, nakanishi received an information from a (b)(6) dealer explaining that a bur fell apart in a patient's mouth and the patient swallowed the bur.Details are as follows.On january 1, 2017, and january 8, 2017, nsk (b)(4) contacted the (b)(6) dealer for more information.On january 9, 2017, nsk (b)(4) received the information from the (b)(6) dealer and the details are as follows.- the event occurred on (b)(6) 2016.- the dentist was treating a tooth when the bur flew out of the head into the mouth of the patient.- the patient swallowed the bur.- the child was then sent to a medical hospital be checked where an x-ray was performed in order to identify the location to the bur.- the bur was located inside the stomach in a safe area.- the following morning the child defecated the bur during a toilet round so the bur was discharged.- a second x-ray was taken to confirm that everything was ok.

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 m600lg m4 device (serial number (b)(4)).There were no problems observed during the manufacturing or testing noted in the dhr.B) nakanishi conducted a visual inspection of the returned device.B.1) nakanishi did not observe any damage on the exterior.C) rotation check c.1) nakanishi rotated the handpiece with air pressure of 0.25mpa at the handpiece hose connection point and observed abnormal sound and abnormal vibration.D) performance test d.1) nakanishi conducted performance test on the returned handpiece according to the company product inspection criteria.D.2) nakanishi observed that the actual value of bur retention force, rotation speed, noise, and vibration were out of standard value.D.3) nakanishi measured the bur retention force using a test bur (1.598mm in diameter).Nakanishi confirmed that the retention force was 17.9n which indicates a decrease in retention force as the nakanishi standard value is 25n or greater.E) returned bur investigation e.1) nakanishi measured the length, shank diameter, and working part diameter of the nine burs that were returned to nakanishi with the subject handpiece.E.2) the measurements of the shank diameter of the burs were within the product specification (1.590mm - 1.600mm) but closer to the lower limit.E.3) working part diameter of one of the nine burs was greater than the upper limit specified in the operation manual.F) cutting confirmation f.1) nakanishi tried to conduct a simulated cutting with the nine returned burs, but nakanishi observed that each of the burs came out of the handpiece upon starting rotation.G) cartridge overhauls g.1) nakanishi disassembled the handpiece cartridge and performed a visual inspection of the inside parts.G.2) nakanishi observed that the retainer (ball retaining plastic part) and race (ball rolling surface) of the front side (bur insertion side) bearing were worn.G.3) nakanishi cut the chuck open and observed the bur retention part.Nakanishi confirmed accumulation of dirt and abrasion on the bur retention part.G.4) nakanishi then replaced the cartridge with a new one.Nakanishi conducted simulated cutting using a copper plate and melamine resin plate with each returned bur attached to the subject handpiece.The burs did not come off the handpiece during the cutting test once the damaged cartridge had been replaced.G.5) nakanishi took photographs of all the disassembled parts and kept them in a file.H) conclusion reached based on the investigation and analysis result: h.1) as a result of the investigation, nakanishi identified significant deterioration of the bur retention force.This deterioration made the burs come off the handpiece.H.2) nakanishi identified the accumulation of dirt due to insufficient maintenance in the chuck as one of the factors that caused the deterioration of the bur retention force.When dirt exists inside a chuck, sufficient retention force cannot be obtained, which causes slippage of a bur when cutting teeth.Nakanishi determines that the bur retention force had deteriorated due to the repeated slippage causing chuck abrasion.Insufficient maintenance was confirmed from the observation of disassembled cartridge.H.3) nakanishi identifies high load cutting as another factor that caused the bur retention force deterioration.When a bur with a large working part diameter is used, the bur slips due to high load cutting cased by increased cutting resistance.Repeated slippage of a bur wears the chuck, which causes bur retention force deterioration.Working part diameter of one of the nine burs returned from the customer was larger than 2mm and might have caused high load cutting.Nakanishi determines that rotation without alignment due to the insufficient maintenance also increased cutting resistance.H.4) nakanishi concluded that the cause of the malfunction was retention force deterioration due to the user not observing the maintenance and burs for use indicated in the operation manual.H.5) in order to prevent a recurrence of the bur coming off, nakanishi took the following actions: h.5.1) nakanishi reviewed the operation manual and reconfirmed clarity and understandability of the instructions.H.5.2) nakanishi reported the above evaluation results to the distributor and reminded the distributor of: - the risk of use under high load - the importance of maintenance (cleaning) as instructed in the operation manual, and - the importance of choice of correct burs.Nakanishi contacted the distributor for patient infromation on february 17, 2017, february 26, 2017, and february 27, 2017, but the distributor did not disclose the patient information.

• Brand Name: NSK
• Type of Device: HANDPIECE, AIR-POWERED, DENTAL
• 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 ; 1201 richardson dr.; suite 160; richardson, TX 75080 ; 9724809554
• MDR Report Key: 6263349
• MDR Text Key: 65248880
• Report Number: 9611253-2017-00002
• Device Sequence Number: 1
• Product Code: EFB
• Combination Product (y/n): N
• Reporter Country Code: TU
• PMA/PMN Number: K962543
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: distributor,foreign
• Reporter Occupation: Other
• Type of Report: Initial,Followup
• Report Date: 03/16/2017

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 01/19/2017
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: No
• Device Operator: Dentist
• Device Model Number: M600LG
• Device Catalogue Number: P1104001
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 01/16/2017
• Is the Reporter a Health Professional?: No
• Date Manufacturer Received: 12/31/2016
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 07/23/2013
• Is the Device Single Use?: No
• Is This a Reprocessed and Reused Single-Use Device?: No
• Type of Device Usage: Reuse
• Patient Sequence Number: 1
• Patient Outcome(s): Other