Accidental ingestion is common and can even necessitate surgery. An 89-year-old man with dementia presented with abdominal distension and pain. A CT scan revealed a high-intensity object in the terminal ileum with distension of the proximal small intestine. Colonoscopy showed ileus caused by a retained foreign body (FB), which was removed via laparotomy the following day. Chemical analysis identified the material of the FB as platinum silicone rubber. Based on its material and irregular shape, the FB was determined to be a dental impression. The patient had dentures made one year prior, and cognitive decline may have contributed to the incident. Platinum silicone, which is odorless and does not deform with body heat or digestive juices, maybe a common cause of accidental ingestion.