Effects of thermal insult on bone tissue as observed by micro computed tomography

Abstract

Abstract A thorough understanding of the effects of heat on bone morphology is required for reliable analysis of burnt skeletal remains in forensic anthropology and bioarchaeology. However, thermal damage often prevents application of the usual analytical techniques in both modern and archaeological contexts. This study uses Micro Computed Tomography (MicroCT) to assess heat-induced changes in incinerated bovine (Bos taurus) long bones at temperatures between 100 and 700 °C. Scans provided data on bone porosity and surface to volume ratio, which were compared between samples. Macroscopic comparisons were also undertaken using 3D reconstructions of samples. Results showed a decrease in porosity between unburned samples and those burned at the highest temperature (700 °C). This change was not unidirectional, with an unexpected increase at 500 °C. The lack of uniform exponential change suggests that more than one mechanism influences bone morphology in response to thermal insult. The initial significant decrease in porosity may be attributed to the loss of organic material (100–200 °C) which had the most dramatic impact on bone morphology, whereas the increase at 500°C coincides with hydroxyapatite re-crystallisation which is known to occur around this temperature. This study demonstrates that MicroCT can be readily applied to burned bone which is often fragile and difficult to examine. Additionally, unlike most microscopic techniques MicroCT is three dimensional, allowing the internal structure of the entire bone to be investigated without destruction of the sample. The changes observed in bone morphology due to heating provide valuable insight which can inform subsequent investigation and analysis of these samples.