This mdr is being reported at this time as part of our internal review of past complaints and service records.Due to the incident being in the past, we are limited in the info that we can obtain from the initial complainant.Event summary: according to the dentist, a bur detached from a handpiece during a treatment and the pt accidentally swallowed the bur.The bur was observed in the stomach by an x-ray examination.According to the info obtained by the dist, the doctor judged this was no problem, and the pt was satisfied with the dentist.The pt did not experience any significant physical issues.Complaint review: there had not been any prior complaints received for this unit.
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Investigation: nakanishi received the handpiece on 10/02/2013 and conducted an analysis and investigation.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 retention force of the operating device (c131002-02-1).These activities are described in more detail below: methodology used: nakanishi examined the device history records for the subject ti-max a600l (serial number (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 measured burr detachment force by setting a test burr in the handpiece and confirmed it was 22.2n.Nakanishi's acceptance criteria for the burr detachment force is 14.7n or above, indicating that the burr detachment force of the subject handpiece had not deteriorated.Nakanishi disassembled the handpiece to observe the inside of the chuck, compared to an unused new chuck and took photographs.Nakanishi observed the retention surface of the chuck had worn.Conclusion reached: based on the observations during above, nakanishi believes that the bur detached from the handpiece due to the deterioration of the burr retention torque that was caused by the worn chuck.Nakanishi believes that there are two causes for the wear of the chuck: the handpiece had been used with the dirt and debris inside the chuck.The handpiece was used under the load and rotational speed that were higher than those specified with the retention capacity of the chuck.
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