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

Model Number S-MAX M600L

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

Patient Problem No Known Impact Or Consequence To Patient (2692)

Event Date 07/29/2016

Event Type  Injury  

Manufacturer Narrative

Nakanishi was not informed of the patient identifier and weight when receiving the initial information.Nakanishi will try to obtain the information at the next visit to the dentist scheduled in (b)(6).

Event Description

On (b)(6) 2016, nakanishi received a phone call from a distributor regarding a bur coming off from an nsk handpiece.The details are as follows.On (b)(6) 2016, a dentist was providing a patient with an oral cavity preparation.The bur suddenly came off from the handpiece in the patient's mouth.The dentist found the bur around the patient's throat and tried to pick the bur up with a suction instrument.The dentist confirmed the bur was removed from the patient's mouth.

Manufacturer Narrative

On september 7, 2016, nakanishi visited the dentist and tried to obtain the patient identifier and weight, but the dentist did not provide the information.Upon receiving the device involved in the mdr event from a distributor, nakanishi conducted a failure analysis of the returned device (b)(4).These activities are described in more detail below.Methodology used: nakanishi examined the device history record and the repair history for the subject s-max m600l device [serial number (b)(4)].There were no problems observed during the manufacturing or testing noted in the dhr.The repair history showed 1 service record ((b)(6) 2016) since the device was shipped.According to the service record, after repairing the handpiece (replacement of headcap and cartridge), nakanishi performed all of the necessary operation checks.Nakanishi confirmed that all of the criteria were met.Nakanishi measured the bur retention force with a 1.598mm (diameter) test bur.The value nakanishi observed was 25.7n, which meets the company criteria (25n or greater).Nakanishi tried cutting a crown and melamine using the returned bur attached to the returned handpiece to see whether or not the bur would come off.The bur did not come off during the cutting test.Nakanishi disassembled the handpiece cartridge and performed a visual inspection of the chuck.There was abrasion that may have been caused by bur slippage (slip traces) on the bur holding part.Nakanishi checked the diameter of the bur shank and confirmed that the bur was compliant with the iso standard.During the diameter confirmation, nakanishi also observed slip traces marked in the direction of rotation on the bur shank.Additionally, nakanishi found rotational contact traces on the side of the pusher that comes in contact with the push button when it is pressed, as well as on the surface of the cartridge pusher inside the headcap.Nakanishi took photographs of all of the damages on the disassembled parts and kept them in a file.Conclusions reached based on the investigation and analysis results: nakanishi identified from all of the traces formed by cutting under high load that the cause of the reported bur coming off was load exceeding the bur retention force applied to the bur during cutting.Nakanishi also considers the possibility from many years of experience that the cause of the bur coming off was bur slippage caused by insufficient bur retention force due to ingress of dirt/foreign materials into the chuck.Misuse by the user leads to operation under high load, and a lack of maintenance causes the accumulation of dirt/foreign materials in the inside part, which contributes to the reported bur coming off.In order to prevent a recurrence of the bur coming off, 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 the dentist and reminded the dentist of the risk of use under high load and the importance of maintenance (cleaning), as instructed in the operation manual.

• 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: 5899576
• MDR Text Key: 52841061
• Report Number: 9611253-2016-00044
• Device Sequence Number: 1
• Product Code: EFB
• Combination Product (y/n): N
• Reporter Country Code: JA
• 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: 12/22/2016

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: No
• Is this a Product Problem Report?: Yes
• Device Operator: Dentist
• Device Model Number: S-MAX M600L
• Device Catalogue Number: P1002
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 08/04/2016
• Is the Reporter a Health Professional?: No
• Initial Date Manufacturer Received: 07/29/2016
• Initial Date FDA Received: 08/24/2016
• Supplement Dates Manufacturer Received: Not provided
• Supplement Dates FDA Received: 12/23/2016
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 07/11/2012
• 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
• Patient Age: 69 YR