Mineralisation within human tooth cementum identified by secondary ion mass spectrometry†
Life-history parameters such as pregnancies, skeletal trauma, and renal disease have previously been identified from hypomineralised growth layers (incremental lines) of acellular extrinsic fibre cementum (AEFC) using optical microscopy. We show that the precise periodicity of these growth layers remains poorly understood, so life history parameters for putative cementum deposition periodicity cannot be rigorously calculated. In an attempt to better understand the underlying formation processes, our study investigates whether or not mineralisation of AEFC incremental lines clearly indicate life history parameters in an ideal sample, using light microscopy, electron microscopy, and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Based on our results we reject the possibility of accurate estimation of the distribution of mineralisation of tooth cementum using light and scanning electron microscopy alone. On the other hand, we detect an apparent drop in calcium in the AEFC of a patient with six documented full-term pregnancies, using ToF SIMS. We conclude that although ToF-SIMS analysis holds great promise for increasing our knowledge of cementum composition, far more caution is required by researchers linking observed lines in this tissue to underlying causal life history mechanisms and explanations.