Identification of dental implant lot numbers in an unidentified cremated individual using industrial computed tomography: A case report

Dental implants are increasingly used as prosthetic replacements for missing teeth and have gained forensic importance as identifiers, particularly when compared to antemortem images. In the absence of such records, implant-specific features must be examined. We report the attempted identification of a Straumann® (Basel, Switzerland) implant recovered from the cremated remains of an unidentified individual. The remains, discovered on a coastal site, contained eight maxillary and mandibular implants. Despite these distinctive findings, the identity of the individual remained unknown following forensic autopsy. Suspecting Straumann® as the manufacturer, we assumed the presence of an engraved lot number and retrieved the implants. As the superstructure could not be removed, imaging was performed using a nano-focus computed tomography (CT) scanner (Phoenix Nanotom M; Baker Hughes Japan Co., Ltd., Tokyo, Japan). Scanning parameters were tube voltage 150 kV, tube current 80 μA, and voxel size 3.0 μm, enabling visualization of the lot number area. The identified lot number was verified with Straumann® through police channels. The most specific match indicated the distribution of the implant fixture lot to 63 dental clinics in Japan. Although previous studies have suggested the persistence of implant lot numbers after cremation, nondestructive visualization using industrial nano-focus CT imaging has not been reported. This case highlights the utility of nano-focus CT scanning in forensic dental identification, particularly when conventional radiography or medical CT evaluation is insufficient. For large-scale disaster preparedness, the standardized engraving of traceable markings on dental prostheses should be prioritized to enhance identification efforts.