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

Model Number SGS-E2S

Device Problems Nonstandard Device (1420); Overheating of Device (1437); Temperature Problem (3022)

Patient Problems Burn(s) (1757); Injury (2348); Patient Problem/Medical Problem (2688); Partial thickness (Second Degree) Burn (2694)

Event Date 11/02/2018

Event Type  Injury  

Manufacturer Narrative

(b)(4).According to the distributor, the dentist refused to provide the patient's age and weight.

Event Description

On (b)(6) 2018, nakanishi received an e-mail from a (b)(4) about a handpiece overheating.Details are as follows.The event occurred on (b)(6) 2018.The dentist was performing a surgical extraction of #3 on patient using the sgs-e2s handpiece (serial no.(b)(4)).The patient was under local anesthesia.While sectioning the tooth in the surgical extraction, the dentist removed the handpiece from the patient's mouth and became aware of a second degree burn on the lower right-side lip.The burn was circular in shape and approximately 8mm by 12mm in size.The dentist applied cool gauze to the burn and neosporin to the exterior of the lip.There were no abnormalities in the device observed prior to use.The dentist has followed up with the patient and observed the burn was healing normally.The dentist determined that no further medical attention was required for the injury.

Manufacturer Narrative

Upon receiving the device involved in the mdr event from the distributor, nakanishi conducted a failure analysis of the returned device that included measuring the operating temperature of the device [(b)(4)].These activities are described in more detail below.Methodology used: nakanishi examined the device history record and the repair history for the subject sgs-e2s device [serial number (b)(4)].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.Nakanishi conducted a visual inspection of the returned device and performed a simple movement test.There were no visible abnormalities, such as cracks or dents, 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 conducted temperature testing of the returned device in the following manner: temperature sensors were attached to the exterior of the device at various test points.This included the point most proximal to the patient (testing point (1)) and points further toward the distal end of the device (testing points (2) through (4)).The test setup 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 temperature) to each of the testing points.Nakanishi rotated the device's motor at 40,000 min-1, which is the maximum rpm for the motor that drives the handpiece (80,000 min-1 for the handpiece), with water spray, and measured the exothermic response.Nakanishi measured the temperature rise of the returned handpiece set at 80,000 min-1 (motor revolution 40,000 min-1).Nakanishi observed an abnormal temperature rise at test point (4) several tens seconds after the start.Temperature measurements 5 minutes after the start are as follows: test point (1): 46.2 degrees c, test point (2): 45.8 degrees c, test point (3): 48.5 degrees c, and test point (4): 55.2 degrees c.Nakanishi cleaned the inside of the handpiece using nakanishi pana spray plus.Nakanishi observed 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 operation manual, nakanishi measured the temperature of the handpiece.There was no abnormal rise in temperature during 300-second-test period.Test point (1): 39.9 degrees c, test point (2): 39.8 degrees c, test point (3): 41.6 degrees c, and test point (4): 46.9 degrees c.Identification of the specific failure mode(s) and/or mechanism(s) and the associated device components involved: a) nakanishi disassembled the handpiece and performed a visual inspection of the inside parts.Nakanishi observed the following phenomena: - there was a great amount of debris on the bearing incorporated in the test point (1).- there was dirty grease on the other parts.B) nakanishi took photographs of all of the disassembled parts and kept them in the investigation report #(b)(4).Conclusions reached based on the investigation and analysis results: nakanishi identified from observation of temperature reduction after spray cleaning, that the cause of the overheating of the returned device was abnormal resistance during rotation caused by the abraded bearing due to the ingress of undesirable materials into the bearing.A lack of maintenance causes the accumulation of debris on the inside parts, which causes debris ingress into the bearing during rotation.This contributes to the handpiece overheating.Nakanishi shipped the updated operation manuals that contain detailed reprocessing methods to nsk america.Nsk america will distribute the updated manuals to the sub-distributors and users including the complainant to convey the detailed reprocessing methods to prevent a recurrence of the handpiece overheating.

• Brand Name: NSK
• Type of Device: HANDPIECE, ROTARY BONE CUTTING
• Manufacturer (Section D): NAKANISHI INC.; 700 shimohinata; kanuma-shi, tochigi-ken 322-8 666; JA 322-8666
• MDR Report Key: 8144442
• MDR Text Key: 129751680
• Report Number: 9611253-2018-00063
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• PMA/PMN Number: K970953
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: company representative
• Remedial Action: Recall
• Type of Report: Initial,Followup
• Report Date: 11/16/2018,01/15/2019

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?: Yes
• Device Operator: Health Professional
• Device Model Number: SGS-E2S
• Device Catalogue Number: H266
• Was Device Available for Evaluation?: No
• Was the Report Sent to FDA?: No
• Distributor Facility Aware Date: 11/14/2018
• Device Age: 2 YR
• Event Location: Outpatient Treatment Facility
• Date Report to Manufacturer: 11/16/2018
• Initial Date Manufacturer Received: 11/16/2018
• Initial Date FDA Received: 12/07/2018
• Supplement Dates Manufacturer Received: 12/18/2018
• Supplement Dates FDA Received: 01/15/2019
• Is This a Reprocessed and Reused Single-Use Device?: No
• Removal/Correction Number: 9611253-060818-001-R
• Patient Sequence Number: 1
• Patient Outcome(s): Other