Effects of thermal exposure on bone surface characteristics and DNA recovery

In forensic cases involving burned human remains, DNA analysis and anthropological techniques are often required to aid identification. There are gaps in the literature regarding how cremation affects DNA preservation and skeletal integrity. This preliminary study aimed to examine how increasing temperature exposures impact DNA recovery and bone surface morphology. Using domestic pig (Sus scrofa) rib bones as a model and a muffle furnace, bones were exposed to temperatures ranging from 100 °C to 800 °C for 30 min. The resulting changes in colour and surface texture were observed both macroscopically and microscopically. DNA was extracted using the Applied Biosystems PrepFiler Express™ BTA Forensic DNA Extraction Kit on the AutoMate Express™ Forensic DNA Extraction System and quantified using a NanoDrop™ One UV-Vis Spectrophotometer. Bone colour changes followed an expected pattern, starting with the natural beige, transitioning to black at 350 °C, and then becoming lighter until reaching white at 800 °C. Microscopic observations showed the presence of surface striations at temperatures below 275 °C and the presence of porosity at temperatures above 275 °C. Bones with a black, grey, or white colour and visible porosity were observed in conjunction with a decrease in the amount of DNA. All the bone samples had DNA amounts exceeding 250 ng, suggesting potential suitability for short tandem repeat (STR) polymerase chain reaction (PCR) amplification. This study furthers our understanding of the impacts of cremation on DNA recovery and bone surface integrity to aid assessment and management of remains.