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

Model Number SGA-E2S

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

Patient Problems Burn(s) (1757); Injury (2348); Burn, Thermal (2530); Patient Problem/Medical Problem (2688)

Event Date 11/09/2019

Event Type  Injury  

Manufacturer Narrative

According to the distributor, the dentist refused to provide the patient's weight.

Event Description

On november 19, 2019, nakanishi became aware of a handpiece overheating through a complaint input into the complaint database by a distributor (nsk america).Details are as follows: the event occurred on (b)(6) 2019.The dentist was removing a horizontal, impacted tooth (#17) from the patient's mouth using the sga-e2s handpiece (serial no.Bbh70042).The patient was under local anesthesia.During the procedure, the tip of the handpiece overheated and caused a burn to the patient's lower lip.The patient was instructed by the dentist to apply ointment to treat the injury site.The burn is reported to be healing normally, but may leave a permanent scar which may require referral to a specialist for treatment.

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 [c191119-01].These activities are described in more detail below.Methodology used: a) nakanishi examined the device history record and the repair history for the subject sga-e2s device [serial no: (b)(6)].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 temperature testing of the returned device in the following manner: b.1) 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.B.2) 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.B.3) 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 (1) a few seconds after the start.Temperature measurements 138 seconds after the start are as follows: test point (1): 57.7 degrees c, test point (2): 43.2 degrees c, test point (3): 29.7 degrees c, test point (4): 31.8 degrees c.The rise in temperature was so sudden that the test was concluded 138 seconds into the planned 5-minute evaluation period.Identification of the specific failure mode(s) and/or mechanism(s) of the associated device components was conducted as follows: a) nakanishi disassembled the handpiece and performed a visual inspection of the internal parts.Nakanishi observed the following phenomena: there was a great amount of debris on the bearing incorporated at test point (1).There was also debris on the other parts.B) nakanishi took photographs of all of the disassembled parts and kept them in investigation report#: c191119-01.Conclusions reached based on the investigation and analysis results: a) nakanishi identified that the cause of the overheating of the returned device was abnormal resistance during rotation caused by the soiled bearing due to the ingress of undesirable materials into the bearing.B) a lack of maintenance caused the accumulation of debris on the internal parts, which caused debris ingress into the bearing during rotation.This contributed to the handpiece overheating.C) in order to prevent a recurrence of the handpiece overheating, nakanishi took the following actions: c.1) nakanishi reviewed the operation manual and reconfirmed the clarity and understandability of the instructions.C.2) nakanishi reported the above evaluation results to nsk america and directed nsk america to remind the user of the importance of maintenance, as instructed in the operation manual.

Manufacturer Narrative

This supplemental report is sent as a correction because the initial report was inadvertently considered by fda to be a single mdr report.This supplement report clarifies that the same event was initially reported separately by both the manufacturer and the initial importer and the initial manufacturer report was therefore not intended as a single mdr report.The original report included on the front page both the manufacturer report number and the importer report number to cross-reference each report per "general instructions - for form fda 3500a medwatch (for mandatory reporting)" (form fda 3500a supplement (4/16) - form instructions).However, fda is in the process of updating the instructions to form 3500a to clarify that the cross-reference information should instead be placed in section h.10.This supplemental report now places the initial importer report number (1422375-2019-00021) in section h10 additional manufacturer narrative for cross-reference purposes, as requested by fda.

• 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: 9422239
• MDR Text Key: 184880566
• Report Number: 9611253-2019-00054
• Device Sequence Number: 1
• Product Code: KMW
• Combination Product (y/n): N
• PMA/PMN Number: K171155
• 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,Followup
• Report Date: 12/24/2020

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 12/06/2019
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: Yes
• Device Operator: Health Professional
• Device Model Number: SGA-E2S
• Device Catalogue Number: H265
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 12/04/2019
• Date Manufacturer Received: 12/10/2020
• 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
• Patient Age: 23 YR