MAUDE Adverse Event Report: NAKANISHI INC. NSK; HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL

Model Number Z95L

Device Problems Break (1069); Mechanical Problem (1384); Detachment of Device or Device Component (2907); Device Fell (4014)

Patient Problems No Consequences Or Impact To Patient (2199); Patient Problem/Medical Problem (2688); No Known Impact Or Consequence To Patient (2692)

Event Date 02/20/2019

Event Type  malfunction  

Event Description

On (b)(6) 2019, nakanishi received a phone call from a distributor about a problem with an nsk handpiece.The details of the event are as follows.The event occurred on (b)(6) 2019.A dentist was removing an inlay from a patient's tooth using the z95l handpiece.During the procedure, the headcap broke into pieces and fell into the patient's mouth.The dentist retrieved the broken headcap from the patient's mouth.The handpiece involved in the event was a loaner while the original z95l handpiece owned by the dental office was being repaired.

Manufacturer Narrative

The dentist refused to provide the patient's id, age and weight.Upon receiving the device involved in the mdr event, nakanishi conducted a failure analysis of the returned device [c190220-07].These activities are described in more detail below.Methodology used: a) nakanishi examined the device history record and the repair history for the subject z95l device [serial number 0bc80169].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) nakanishi conducted a visual inspection of the headcap and threads of the returned device.There were no visual abnormalities, such as abrasion or deterioration.Nakanishi also observed no abnormalities in the adhesive trace on the headcap and threads, which indicates that the adhesive was appropriately applied to the parts.C) nakanishi attached the headcap to the returned handpiece and observed whether or not the headcap would loosen by rotating the handpiece motor under no load and then cutting a melamine plate and a copper plate at the maximum speed (200,000min-1).The headcap did not loosen during the evaluation.Conclusions reached based on the investigation and analysis results: 1) although nakanishi could not replicate the reported event, nakanishi considers the possibility, from similar phenomena that nsk has experienced in the past, that the combination of a strong impact on the device with cutting vibration could result in the reported headcap loosening/detachment.2) failure to check the headcap tightness before each use as instructed in the operation manual contributes to the headcap loosening/detachment.3) in order to prevent a recurrence of the headcap loosening/coming off, nakanishi took the following actions: 3.1) nakanishi reviewed the operation manual and reconfirmed clarity and understandability of the instructions.3.2) nakanishi reported the above evaluation results to the dentist and reminded the dentist of the importance of checking the handpiece before use as instructed in the operation manual.

Event Description

In the subsequent investigation, nakanishi found that the headcap had fallen into the patient's mouth without breaking into pieces.

• Brand Name: NSK
• Type of Device: HANDPIECE, CONTRA- AND RIGHT-ANGLE ATTACHMENT, DENTAL
• Manufacturer (Section D): NAKANISHI INC.; 700 shimohinata; kanuma-shi, tochigi-ken 322-8 666; JA 322-8666
• MDR Report Key: 8430215
• MDR Text Key: 139205630
• Report Number: 9611253-2019-00013
• Device Sequence Number: 1
• Product Code: EGS
• Combination Product (y/n): N
• PMA/PMN Number: K972569
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: distributor,foreign
• Type of Report: Initial,Followup
• Report Date: 04/12/2019

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: Health Professional
• Device Model Number: Z95L
• Device Catalogue Number: C1034
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 02/26/2019
• Initial Date Manufacturer Received: 02/20/2019
• Initial Date FDA Received: 03/18/2019
• Supplement Dates Manufacturer Received: 03/19/2019
• Supplement Dates FDA Received: 04/12/2019
• Is This a Reprocessed and Reused Single-Use Device?: No
• Patient Sequence Number: 1
• Patient Outcome(s): Other