MAUDE Adverse Event Report: NAKANISHI, INC. (NSK) NSK Z95L; HANDPIECE,ROTARY BONE CUTTING, PRODUCT CODE: KMW

Model Number Z95L

Device Problem Temperature Problem (3022)

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

Event Type  malfunction  

Event Description

This mdr is being reported at this time as part of our internal review of past complaint and service records.Due to the incident being in the past.We are limited in the information that we can obtain from the initial complainant.Event information: during treatment.The handpiece head heated up and the patient complained that it was hot.The dentist did not inform nakanishi of this event when it occurred.The dentist requested nakanishi to check this handpiece.Nakanishi repaired this handpiece on (b)(6) 2014 and returned it to the dentist.

Manufacturer Narrative

Upon receipt from the dentist of the device involved in the mdr event, nakanishi conducted a failure analysis of the returned device that included an attempt to measure the temperature of the operating device ((b)(4)).These activities are described in more detail below.Methodology used: nakanishi conducted a visual inspection of the returned device and performed a simple movement test.There were no visible abnormalities, such as cracks or debris, on the outside of the handpiece.Nakanishi then set a test bur in the handpiece and rotated it by hand.Nakanishi observed that the bur did not rotate smoothly.The device was configured for temperature testing in the exact state in which it was returned.Specifically, no lubrication or cleaning was performed on the returned device before this first test in order to characterize the device under conditions that would duplicate the use situation at the time of the event.Temperature sensors were first attached to the exterior of the device at two test points (i.E., most proximal to the patient and the distal end of the device).The test set up was prepared to take temperature measurements at all points simultaneously, including a reference measurement at ambient room temperature.Nakanishi attached a thermocouple (sensor to measure a temperature) to each of the testing points.Nakanishi rotated the handpiece at 40,000 rpm, which is maximum rpm for the motor that drives the handpiece (200,000 rpm for the handpiece), with water spray and measured the exothermic situation.Nakanishi measured the temperature rise of the returned handpiece set at 200,000 rpm (motor revolution 40,000 rpm).Nakanishi confirmed the temperature at the head of the handpiece heated up (more than 47.9 degrees at the side of head and more than 54.0 degrees at a part of head cap) into the 3-minute evaluation period.Identification of the specific failure mode(s) and/or mechanism(s) and the associated device components(s) involved : nakanishi disassembled the handpiece and performed a visual inspection of the inside parts.Nakanishi observed damage on the cartridge bearing.The amount of oil observed inside the handpiece indicated that the device was not adequately cleaned.Due to the oil level observed, as well as the presence of some abrasive powders in the handpiece, nakanishi reassembled and washed the handpiece using nakanishi pana-spray.Nakanishi observed dirt/debris being expelled from the head of the handpiece by using a white filter to catch anything that was expelled.After cleaning and lubricating the handpiece as defined in the operations manual, nakanishi measured the temperature of the handpiece.Even after cleaning, nakanishi still observed a quick rise in temperature.Conclusions reached based on the investigation and analysis results : nakanishi identified that the cause of overheating of the returned device was due to damage to the cartridge bearing.The damage observed caused abnormal rotational resistance, which would result in the handpiece overheating.

• Brand Name: NSK Z95L
• Type of Device: HANDPIECE,ROTARY BONE CUTTING, PRODUCT CODE: KMW
• Manufacturer (Section D): NAKANISHI, INC. (NSK); 700 shimohinata; kanuma-shi, tochigi-ken 322- 8666; JA 322-8666
• Manufacturer (Section G): NAKANISHI, INC. (NSK); 700 shimohinata; kanuma-shi, tochigi-ken 322- 8666; JA 322-8666
• Manufacturer Contact: ken block ; 1201 richardson dr. ste 280; richardson, TX 75080 ; 9724809554
• MDR Report Key: 4690563
• MDR Text Key: 5646088
• Report Number: 9611253-2015-00043
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: JA
• PMA/PMN Number: K970953
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: Distributor
• Reporter Occupation: Service Personnel
• Type of Report: Initial
• Report Date: 03/27/2015

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 04/08/2015
• Is this an Adverse Event Report?: No
• Is this a Product Problem Report?: Yes
• Device Operator: Other
• Device Model Number: Z95L
• Device Catalogue Number: C1034001
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 06/12/2014
• Is the Reporter a Health Professional?: No
• Date Manufacturer Received: 06/12/2014
• Was Device Evaluated by Manufacturer?: Yes
• Date Device Manufactured: 12/05/2012
• 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