MAUDE Adverse Event Report: NAKANISHI INC. MASTER II MINI PUSH BUTTON; HANDPIECE, AIR-POWERED, DENTAL

Model Number MASTER II MINI PUSH BUTTON

Device Problems Break (1069); Detachment Of Device Component (1104)

Patient Problems Foreign Body In Patient (2687); No Known Impact Or Consequence To Patient (2692)

Event Date 07/22/2015

Event Type  Injury  

Event Description

On (b)(6) 2012, nakanishi received an e-mail from (b)(6) ((b)(4)) about a device manufactured by nakanishi for (b)(4).The information nakanishi received in the e-mail is - on (b)(6) 2015, a dentist was performing a restorative dentistry procedure on a patient - during the procedure, the bur broke and fell into the patient's mouth.- the patient was not harmed nor injured.- the bur was retrieved from the patient's mouth.- the dentist did not provide specific patient information.On (b)(6) 2015, nakanishi e-mailed (b)(4) requesting additional information about the events including patient information.There was no additional information at that moment.

Manufacturer Narrative

On november 27, 2015, nakanishi contacted the distributor ((b)(4)) for additional information such as patient information by email, however, nakanishi has not heard back from them since then.On september 25, nakanishi received 6 handpieces from (b)(4) without identification which handpiece caused the subject events.Upon receipt of the aforementioned handpieces, nakanishi conducted a failure analysis of all the returned devices.These activities are described in more detail below.Methodology used: device history record: nakanishi examined the device history record for all the master ii mini push buttons nakanishi received [serial numbers (b)(4)].There were no problems observed during the manufacturing or testing noted in the dhr.Abnormal noises: nakanishi set a test bur in the handpieces and rotated them.Nakanishi confirmed abnormal noises from all the handpieces.Bur retention force: nakanishi measured the bur retention force for all the handpieces and measurement values are as follows: s/n (b)(4): 19.6n, s/n (b)(4): 21.1n, s/n (b)(4): 21.9n, s/n (b)(4): 22n, s/n (b)(4): 18.4n, s/n (b)(4): 16.9n.Nakanishi confirmed that all of the handpieces met the specifications (14.7 - 39.2n), however, the above evaluation indicates that the handpiece s/n (b)(4) has the lowest retention force among the six.Nakanishi also conducted a mock cutting test using a brass plate and melamine resin with carbide bur fg557 and confirmed that no bur came off.Rotation speed: nakanishi measured the rotation speed of the handpieces using a tachometer and measurement values are as follows: s/n (b)(4): 433.9krpm, s/n (b)(4): 436.6krpm, s/n (b)(4): 434.5krpm, s/n (b)(4): 429.4krpm, s/n (b)(4): 427.1krpm, s/n (b)(4): 357.7krpm.Nakanishi confirmed that five out of six handpieces met the required specifications (400krpm-500krpm), but handpiece s/n (b)(4) did not meet the lower limit.Visual inspection of rotation: nakanishi confirmed that five out of six handpieces rotated normally, but handpiece s/n (b)(4) had an unstable rotation.Labeling review: nakanishi requires the users in the operation manual to use burs compliant with iso 1797-1 type 3 with diameter 1.59 through 1.6 mm for the appropriate operation.Visual inspection of inner parts: based on the results above, nakanishi disassembled the handpiece (s/n (b)(4)) and performed a visual inspection of the inside parts.Nakanishi observed abrasion of f-bearing and abrasive powders on the retainer balls.Nakanishi took photographs of all the abrasion and abrasive powder mentioned above and kept them in a file.Conclusion reached based on the investigation and analysis results: despite nakanishi not identifying the cause of the failure, nakanishi considers the possibility from the above failure analysis that the bur of the device with a serial number, (b)(4), may have came off in the patient mouth due to abnormal vibration, use of bur with diameter smaller than what iso requires and high-load operation.In order to prevent recurrence of the bur coming off, nakanishi took the following actions : nakanishi first reviewed the operation manual and ensured clarity, understandability and feasibility of the instructions.Nakanishi reported the above evaluation results to (b)(4) and directed (b)(4) to remind the user of the importance of maintenance and use as instructed in the operation manual.

• Brand Name: MASTER II MINI PUSH BUTTON
• 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: ken block ; 1201 richardson dr.; suite 160; richardson, TX 75080 ; 9724809544
• MDR Report Key: 5060049
• MDR Text Key: 25102564
• Report Number: 9611253-2015-00111
• Device Sequence Number: 1
• Product Code: EFB
• Combination Product (y/n): N
• Reporter Country Code: US
• 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: Followup
• Report Date: 06/01/2016

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: MASTER II MINI PUSH BUTTON
• Device Catalogue Number: 9004613
• Is the Reporter a Health Professional?: No
• Initial Date Manufacturer Received: Not provided
• Initial Date FDA Received: 09/08/2015
• Supplement Dates Manufacturer Received: Not provided
• Supplement Dates FDA Received: 06/01/2016
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 03/04/2015
• 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