Bite marks can provide important evidence in criminal cases. To collect this evidence, investigators take impressions of bite marks using materials like polyvinyl siloxane or alginate. The impression material is applied directly to the injury and reinforced with cotton and dental plaster. This process creates dental stone models of the bite mark that can be analyzed and presented in court. However, impressions may not always be possible if the victim is living or there is excessive swelling at the injury site.