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

Model Number Z800L

Device Problems Detachment Of Device Component (1104); Component Falling (1105); Loose or Intermittent Connection (1371); Mechanical Problem (1384); Detachment of Device or Device Component (2907)

Patient Problems Injury (2348); Foreign Body In Patient (2687); Patient Problem/Medical Problem (2688)

Event Date 11/15/2016

Event Type  Injury  

Manufacturer Narrative

The dentist did not disclose the patient's name.

Event Description

On november 22, 2016, an nsk handpiece z800l (serial number (b)(4)) was returned to nakanishi from a distributor for repair.There was a note with the handpiece stating the bur fell out of the handpiece and injured a patient.On november 25, 2016, nakanishi contacted the dentist for more information.The information nakanishi obtained is as follows.The event occurred on (b)(6) 2016.The dentist was preparing a crown for tooth #7 in the lower left jaw using the z800l.The chuck part loosened, and the bur fell out during the treatment.The bur stuck in the patient's oral mucosa.The dentist felt the bur shortage and exchanged it for a new bur prior to use.The dentist disinfected the patient.According to the dentist, there was no follow-up necessary with the patient.

Manufacturer Narrative

Upon receipt of the device involved in the mdr event from the 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 for the subject z800l device [serial number (b)(4)].There were no problems observed during the manufacturing or testing noted in the dhr.The repair history showed two service records (june 2015, and october 2015) since the device was shipped.The service records showed that all the criteria had been met at the necessary operation checks after the repair (replacement of cartridge and head cap).Nakanishi measured the bur retention force using a test bur (1.589mm in diameter).Nakanishi confirmed that the retention force was 18.1n which indicates a decrease in retention force as the nakanishi standard value is 25n or greater.Cutting check.Nakanishi attached carbide bur 557 and conducted a simulated cutting with a melanine resin.Nakanishi confirmed that the bur came out of the device during normal operation.Cartridge overhauls.Nakanishi disassembled the handpiece cartridge and performed a visual inspection of the chuck.Nakanishi checked the inside of the chuck and observed the accumulation of dirt/foreign materials.Nakanishi also cleaned the dirt inside the chuck, nakanishi observed wear on the chuck.Nakanishi took photographs of all of the damages on the disassembled parts and kept them in a file.Conclusion reached based on the investigation and analysis results: nakanishi identified that the cause of the bur coming off was due to chuck abrasion and application of overload to the bur.Bur retention force is decreased when a chuck is worn, which leads to the bur coming out when overload is applied.Usage under high load leads to a bur coming out, and a lack of maintenance causes the accumulation of dirt/foreign materials.In order to prevent a recurrence of the bur coming out, 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.The importance of maintenance (cleaning) as instructed in the operation manual, and the importance of choosing correct burs.

• 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 ; 9724809552
• MDR Report Key: 6173560
• MDR Text Key: 62345432
• Report Number: 9611253-2016-00069
• Device Sequence Number: 1
• Product Code: EFB
• Combination Product (y/n): N
• Reporter Country Code: JA
• PMA/PMN Number: K113655
• 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: 05/09/2017

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: No
• Device Operator: Dentist
• Device Model Number: Z800L
• Device Catalogue Number: P1110001
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 11/22/2016
• Is the Reporter a Health Professional?: No
• Initial Date Manufacturer Received: 11/22/2016
• Initial Date FDA Received: 12/14/2016
• Supplement Dates Manufacturer Received: Not provided
• Supplement Dates FDA Received: 05/10/2017
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 04/08/2015
• 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: 40 YR
• Patient Weight: 65