Ana Ribeiro

Objectives: The modern human mandibular symphysis displays a mental prominence, a unique trait in the human lineage. Beyond this shared pattern, considerable variability in shape and metrics exists. This heterogeneity is thought to result from multiple mechanisms, including biomechanical compensation, allometric and dietary effects, population genetics, or sexual dimorphism. While the influence of these processes on overall mandibular shape is thoroughly documented, limited information exists on their effects on the distribution of mandibular cortical bone. Thus, this study assessed the impact of local and global allometry, sexual dimorphism, and cortical area on the shape and size of the symphyseal cortical bone contours. Methods: We analyzed computed tomography images of 62 modern human mandibles using Elliptic Fourier Descriptors. The effects of the investigated variables on external and internal cortical bone shapes and sizes were tested using a nested multivariate approach and predicted shape reconstructions were used to visualize morphological variation. Results: In this sample, sex, and local allometry had significant effects on mandibular symphyseal shape and sex was the main predictor of local allometry. Cortical area significantly affected the shape and size of the external cortical bone contour and body weight influenced the size of the internal cortical bone contour. Conclusion: Sexual dimorphism, allometric effects, and biomechanical compensation impact the shape and size of the mandibular symphysis. External and internal cortical bone contours respond differently to these effects. Future studies could investigate the influence of other relevant factors on symphyseal shape and size.

The human mandibular symphysis concentrates multiaxial loads during function and remodels throughout growth, but the precise mechanisms underlying cortical bone shape during growth remain relatively unexplored. Approaches based solely on thickness or external cortical contours provide only partial insights and do not capture the functional, genetic, and allometric interactions driving morphogenesis. In this study, we analyzed symphyseal cross‐sections from 63 subadult mandibles from two French archeological assemblages using elliptic Fourier analysis. Micro‐computed tomography volumes were reconstructed, and external and internal cortical outlines digitized and quantified with Fourier descriptors. Principal component analysis summarized shape variation, and linear models tested the effects of size, age, total cortical area, and geographic origin on each outline. A similar workflow was applied to the size variable expressed as the logarithm of centroid size to test the following predictors: age, total cortical area and archeological site of origin. Across cortical outlines, symphyseal shape was governed primarily by allometry, with a smaller additional contribution of total cortical area. Age significantly affected the inner cortical outline but not the outer one, and geographic origin had no detectable influence. Individuals examined before and after eruption of the first permanent molar occupied largely overlapping morphospaces, indicating a continuous developmental trajectory rather than a shift at eruption. Collectively, the results support bone‐tissue remodeling that progresses throughout growth and is dominated early by size‐related change, with the hypothesis that inter‐individual divergence emerges later. The approach provides a reproducible, resolved framework for quantifying bone remodeling across ontogeny and for testing form‐function relationships.

Objective: We are aimed at describing the clinical and psychosocial benefits of resin infiltration as a minimally invasive treatment option for hypomature amelogenesis imperfecta in a child. Hypomature amelogenesis imperfecta is a rare hereditary enamel defect that significantly compromises dental esthetics, function, and psychosocial well‐being. Conventional management often involves invasive restorative approaches such as composites, veneers, or crowns, which may require removal of sound tooth tissue and pose challenges in pediatric patients. Clinical Considerations: An 11‐year‐old girl presenting with hypomature amelogenesis imperfecta and severe esthetic concerns associated with impaired oral health–related quality of life was treated using an erosion infiltration technique with resin (Icon, DMG). Following enamel surface conditioning, a low‐viscosity resin infiltrant was applied to penetrate and mask hypomature enamel opacities. The procedure led to immediate and significant esthetic improvement, with enhanced enamel translucency and high patient satisfaction. Esthetic outcomes remained stable over a 3‐year follow‐up period, including during orthodontic treatment, and were associated with a marked improvement in oral health–related quality of life. Conclusions: This case highlights the potential of resin infiltration to offer a conservative alternative to conventional restorative methods in hypomature amelogenesis imperfecta, with meaningful improvement in dental esthetics and oral health–related quality of life. Nevertheless, further clinical studies and long‐term follow‐up are required to validate its durability and to establish standardized treatment protocols.