(b)(4).Manufacturing site evaluation: the instrument is available for investigation decontaminated, but not the fragment.Investigation - failure description - the instrument is in a good condition, apart from the missing carbide inlay, no deviations can be found.Investigator carried out the pictorial documentation visually and microscopically.The analysis of the fracture pattern illustrated a forced fracture due to overload.No pores, inclusions or foreign bodies could be found on the point of rupture.The backing material at the point of rupture is bent.Batch history review - the device quality and manufacturing history records for all available lot numbers has been requested.The answer is still pending; the report will be updated upon receipt of the review.No similar incidents have been filed with products from this batch.Conclusion and root cause - based on the information available as well as a result of our investigation the root cause of the failure is most probably related to an insufficient usage.Rationale - the bent backing material is a sign of an overload situation, most likely caused by leverage or torsion which caused the fracture of the carbide.
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