Morphology and spatial distribution of cortical bone canals: Evaluation of shape parameters, lacunarity, and fractal dimension in the human irradiated mandible.

Abstract

This study aimed to assess the spatial distribution of cortical bone canals' network through the analysis of lacunarity (Lac), fractal dimension (FD), and canal morphological parameters in the mandible (IR group, n = 7) of human patients under radiotherapy in comparison with non-irradiated younger (yC group, n = 8) and older (oC group, n = 8) individuals. Patients who underwent mandibular surgery were selected to have bone fragments removed during surgery, and undecalcified histological slides were analyzed by phase-contrast microscopy by two operators. The following morphological parameters were assessed in the Haversian canal (Ca): area (Ca·Ar, μm²), perimeter (Ca·Pm, μm), and circularity (Ca.c, #). Binary images were obtained by manually segmenting canals for Lac and FD analysis through box-counting. A total of 273 canals were segmented in the IR group, 284 in the yC group, and 60 in the oC group. Higher values for canal area and perimeter (p < 0.0001) were found for oC (7871 μm² and 358.9 μm, respectively), followed by IR (2958 μm² and 212.9 μm, respectively), and yC (1286 μm² and 135.8 μm, respectively). Canal circularity was lower for oC (p < 0.0001). Lac and FD did not differ when comparing irradiated individuals with the younger and older individuals. In conclusion, cortical canals are morphologically different when comparing younger and older individuals with patients exposed to ionizing radiation. Alterations on Haversian canals after radiotherapy could have clinical implications, mostly related to vascularization. Lac and FD were reliable parameters in assessing the spatial organization of the canals within the matrix.