Technical note: Micro-computed tomography calibration using dental tissue for bone mineral research

Ian Towle* (Corresponding Author), Carolina Loch, Marc Oxenham, Kristin l. Krueger, Amira Samir salem, Marina Martínez De pinillos, Mario Modesto Mata, Leslea j. Hlusko

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Computed tomography (CT) and microcomputed tomography (μCT) require calibration against density phantoms scanned with specimens or during routine internal calibration for assessment of mineral concentration (MC) and density. In clinical studies involving bone, alternative calibration methods using bodily tissues and fluids (“phantomless” calibration) have been suggested. However, such tissues are seldom available in archeological and osteological research. This study investigates the potential of dental tissue as internal reference for calibration of μCT scans, facilitating the analysis of bone MC. We analyzed 70 molars from 24 extant primate species, including eight human teeth, each scanned with density phantoms for calibration. Our findings indicate that sampling specific regions of molars (lateral aspects of the mesial cusps) yields low variation in enamel and dentine MC values, averaging 1.27 g/cm3 (±0.03) for dentine and 2.25 g/cm3 (±0.03) for enamel. No significant differences were observed across molar types or among scanning procedures, including scanner model, resolution, and filters. An ad hoc test on 12 mandibles revealed low variance in MC between the conventional phantom and dental tissue calibration methods; all 36 measurements (low, medium, and high MC for each mandible) were within 0.05 g/cm3 of each other —81% were within 0.03 g/cm3 and 94% within 0.04 g/cm3. Based on these results, we propose a new “phantomless” calibration technique using these mean enamel and dentine MC values. The presented phantomless calibration method could aid in the assessment of bone pathology and enhance the scope of studies investigating bone structure and physical property variations in archaeological, osteological, and laboratory-based research.
Original languageEnglish
Article numbere24952
Number of pages13
JournalAmerican Journal of Biological Anthropology
Early online date22 May 2024
DOIs
Publication statusE-pub ahead of print - 22 May 2024

Bibliographical note

Collection of the μCT scans was supported by a Sir Thomas Kay Sidey Postdoctoral fellowship from the Faculty of Dentistry, University of Otago, to Ian Towle. We thank staff and facilities of the Otago Micro and Nanoscale Imaging for assistance with Micro-CT scanning. This research was additionally facilitated by the European Research Council within the European Union's Horizon Europe (ERC-2021-ADG, Tied2Teeth, project number 101054659). The authors thank the Study Material Committee from the Primate Research Institute (PRI), Kyoto University, for access to their collections, and T. Ito for assistance during data collection. The research was performed under the Cooperative Research Program of the PRI (2019-C-20). We also thank the museums in New Zealand that provided samples for this study and the curators for their assistance and support, including Otago Museum (E. Burns), Dunedin Museum of Natural Mystery (B. Mahalski), and Auckland Museum (M. Rayner and R. Moore). Last, we thank A. Hara for helpful discussions during the inception of this study. The authors have no conflict of interests to declare. Open access publishing facilitated by University of Otago, as part of the Wiley - University of Otago agreement via the Council of Australian University Librarians.

Data Availability Statement

The data that supports the findings of this study are available in the supplementary material.

Keywords

  • bone mineral concentration
  • micro-CT calibration
  • phantomless calibration, μCT

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