MAUDE Adverse Event Report: NAKANISHI, INC. NSK SGA-E2S; HANDPIECE, ROTARY BONE CUTTING

Model Number SGA-E2S

Device Problem Overheating of Device (1437)

Patient Problem Burn(s) (1757)

Event Type  malfunction  

Event Description

The following information is from (b)(6) to nakanishi inc.(nsk), regarding a device manufactured by nsk.Event summary: on (b)(6), nsk america received a handpiece (model sga-e2s serial (b)(4)) from dealer for repair.Incoming comments stated "over heating.Burnt patient lip".Immediately (b)(6) contacted dealer for dentist information.(b)(6) contacted office manager at dr.Office, received call back from manager.During conversation it was stated the dentist had burned the patient with the handpiece.No information provided on patient or date of the event.(b)(6) attempted contact by telephone and e-mail on (b)(6) 2015 no response and further follow-ups with no response.(b)(6) replaced and forwarded this handpiece to nhq for full evaluation on 06/17/2015.

Manufacturer Narrative

Nakanishi is now investigating this event and will submit additional information including results obtained through the investigation as follow-up report.

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 is included in an attempt to measure the temperature of the operating device.These activities are described in more detail below.Methodology used: as an investigation approach nakanishi inc.(b)(4)(manufacturer) examined the dhr for device (sga-e2s, serial no (b)(4)).There were no problems observed during the manufacturing or testing noted in the dhr; 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; nakanishi measured the temperature of the handpiece.Nakanishi attached a thermocouple (sensor to measure a temperature) to four testing points.Nakanishi took photographs of the configuration of the temperature measurement test.Nakanishi rotated the handpiece at 40,000 rpm which is maximum rpm for the motor that drives the handpiece without water spray and measured the exothermic situation.The temperature reached 72.7 degrees c, 61.6 degrees c, 33.1 degrees c and 30.5 degrees c respectively, 69 seconds after the beginning of the test.Nakanishi created charts using the data for analysis.Identification of the specific failure mode(s) and/or mechanism(s) and the associated device components involved: nakanishi disassembled the handpiece and performed a visual inspection of the inside parts.Nakanishi observed buildup of shavings from worn ball bearing retainer inside the head cap and the cartridge (head cap side).Nakanishi reassembled and washed the handpiece using nakanishi pana-spray per the instruction included in the user manual.Nakanishi observed dirt/debris expelled from the head of the handpiece by using a white filter to catch anything that was expelled.Nakanishi took photographs of the expelled dirt/debris.Nakanishi believes that overheating was caused by the wear of bearing retainer.The dirt/debris accumulated inside the bearing retainer increased the rear bearing load and caused excess heat generation.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 bearing retainer that was caused by accumulated dirt/debris.The damage observed caused abnormal rotational resistance, which would result in the handpiece overheating.

• Brand Name: NSK SGA-E2S
• Type of Device: HANDPIECE, ROTARY BONE CUTTING
• Manufacturer (Section D): NAKANISHI, INC.; 700 shimohinata; kanuma-shi, tochigi-ken 322- 8666; JA 322-8666
• Manufacturer (Section G): NAKANISHI, INC.; 700 shimohinata; kanuma-shi, tochigi-ken ; JA
• Manufacturer Contact: ken block ; 1201 richardson dr.; ste 280; richardson, TX 75080 ; 9724809554
• MDR Report Key: 4926323
• MDR Text Key: 6050226
• Report Number: 9611253-2015-00101
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• Reporter Country Code: US
• PMA/PMN Number: K970953
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: Health Professional,Distributor
• Reporter Occupation: Dentist
• Type of Report: Initial
• Report Date: 07/13/2015

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 07/17/2015
• Is this an Adverse Event Report?: No
• Is this a Product Problem Report?: Yes
• Device Operator: Other
• Device Model Number: SGA-E2S
• Device Catalogue Number: H265
• Was Device Available for Evaluation?: Yes
• Date Returned to Manufacturer: 06/26/2015
• Is the Reporter a Health Professional?: Yes
• Date Manufacturer Received: 06/26/2015
• Was Device Evaluated by Manufacturer?: No
• Date Device Manufactured: 08/04/2009
• Is the Device Single Use?: No
• Is This a Reprocessed and Reused Single-Use Device?: No
• Patient Sequence Number: 1
• Patient Outcome(s): Other