Study of midface dimorphism during growth on clinical CT using surface registration without segmentation: A feasibility study

The development of the human midface is still partly unknown. Despite much research, some aspects of dimorphism and growth trajectories during childhood remain unclear, due to the complexity and interdependence of structures such as the sphenoid bone or the maxilla, although various analytical methods, such as anthropometric measurements, geometric morphometry, and surface registration techniques, have been put in place and continue to be optimized for a better understanding of this complex development. We therefore set out to develop a surface registration method without segmentation, through a MultiSlice Computed Tomography (MSCT) study of midface development in immature children aged 0 to 15 years. This study tested the feasibility of this method by creating mean shapes by sex and age, and producing colorimetric maps of intersex deformation within age and intrasex deformation between adjacent ages, in order to visualize the effects of growth and dimorphism on midface shape, independently of size. To ensure clarity of analysis, only results from individuals aged 3, 9, 11, and 15 years were reported, focusing on the maxillary arch, maxillary sinuses, and palate. The results reveal sex and age differences, observed through voxel contractions and dilations in the images. These deformations appear to be linked to dental eruptions and associated bone remodeling, which also lead to inferior displacement of the maxillary sinuses during growth. Furthermore, it was noted that these processes manifest themselves earlier in female individuals, while male individuals show more robust teeth and structures by the end of puberty. Finally, although the results obtained with this method are promising, further efforts are needed due to the many challenges encountered during the process, and will provide a better understanding of maxillary growth, enabling better prevention of pathologies linked to this zone, better diagnosis, and development of early treatments for these pathologies.