This scientific project (ColecciónRP) arises out of the need to have a reference collection of deciduous teeth for the different investigations pursued by the Dental Anthropology Group (GAD) of the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH). It is the outcome of collaboration between the CENIEH Scientific Culture and Innovation Unit (UCC+I) and the GAD.

This is a citizen science project, as without the dental pieces and the donor data provided during the tooth collection campaigns it would have been impossible to create this collection. It is also supported by the Fundación Española para la Ciencia y la Tecnología (FECYT) – Ministerio de Ciencia, Innovación y Universidades.

The research of the Dental Anthropology Group is focused on hominin dentition from the Pliocene, Pleistocene and Holocene. In addition to classic studies of tooth morphology and dimensions, using the micro-computed axial tomography equipment of the Microscopy and Micro-Computed Tomography Laboratory (MicroCT), it also performs 2D and 3D morphometric analyses of the enamel, dentin and pulp cavity. Taken together with research into other anatomical regions, these studies let us draw inferences about the taxonomy, phylogeny, development and evolutionary scenario of these species.

The main purpose of creating this collection of deciduous teeth is to develop a comparative sample of milk teeth, of worldwide importance, which will assist with important investigations in the spheres of paleoanthropology, anthropology and forensics.

To date, it has already been used in scientific work that has appeared in international journals, such as the papers on the morphology of the deciduous teeth of the fossil species Homo antecessor published by the GAD (Bermúdez de Castro et al., 2017; Martínez de Pinillos et al., 2017), or the studies of sexual dimorphism (the differences between boys and girls) in the tissue composition of the second bottom molar (Hernaiz García, 2017). In addition, the paper about the reference collection itself, published in the American Journal of Physical Anthropology (Martínez de Pinillos et al., 2021), is helping the scientific community to discover this important collection.

Its potential is certainly enormous, and it may be very useful in future studies such as:

• Research into the external (enamel) and internal (dentin) morphological characterization of the teeth using the techniques of micro-computed axial tomography (MicroCT).
• Studies of the pathologies suffered by extinct human populations, where the interest lies not only in their conditions of health or illness, but also in how this relates to the behavior and degree of ecological adaptation of these populations.
• Investigation into the development pattern and dental histology.

Studies of sexual dimorphism to evaluate the variability between men and women, based on the dentition.