Objectives Data on normal mandibular development in the infant is lacking though essential to understand normal growth patterns and to discriminate abnormal growth. The aim of this study was to... Show moreObjectives Data on normal mandibular development in the infant is lacking though essential to understand normal growth patterns and to discriminate abnormal growth. The aim of this study was to provide normal linear measurements of the mandible using computed tomography performed in infants from 0 to 2 years of age. Material and methods 3D voxel software was used to calculate mandibular body length, mandibular ramus length, bicondylar width, bigonial width and the gonial angle. Intra- and inter-rater reliability was assessed for these measurements. They were found to be sufficient for all distances; intra-class correlation coefficients were all above 0.9. Regression analysis for growth modelling was performed. Results In this multi-centre retrospective study, 109 CT scans were found eligible that were performed for various reasons (e.g. trauma, craniosynostosis, craniofacial abscesses). Craniosynostosis patients had larger mandibular measurements compared to non-craniosynostosis patients and were therefore excluded. Fifty-one CT scans were analysed. Conclusions Analysis showed that the mandible increases more in size vertically (the mandibular ramus) than horizontally (the mandibular body). Most of the mandibular growth occurs in the first 6 months. Show less
Dekker, H.; Schulten, E.A.J.M.; Ruijven, L. van; Essen, H.W. van; Blom, G.J.; Bloemena, E.; ... ; Bravenboer, N. 2020
Objectives: The aim of this study was to assess the microarchitecture and turnover in irradiated cancellous mandibular bone and the relation with radiation dose, to elucidate the effects of... Show moreObjectives: The aim of this study was to assess the microarchitecture and turnover in irradiated cancellous mandibular bone and the relation with radiation dose, to elucidate the effects of radiotherapy on the mandible.Patients and methods: Mandibular cancellous bone biopsies were taken from irradiated patients and controls. Micro-CT scanning was performed to analyze microstructural bone parameters. Bone turnover was assessed by histomorphometry. Local radiation dose at the biopsy site (Dmax) was estimated from radiotherapy plans.Results: Twenty-seven irradiated patients and 35 controls were included. Osteoid volume (Osteoid Volume/Bone Volume, OV/BV) [0.066/0.168 (median/interquartile range (IQR), OV/BV; %), P < 0.001], osteoid surface (Osteoid Surface/Bone Surface, OS/BS) [0.772/2.17 (median/IQR, OS/BS; %), P < 0.001] and osteoclasts number (Osteoclasts per millimetre bone surface, Ocl/mmBS; mm(2)) [0.026/0.123 (median/IQR, Ocl/mmBS; mm2), P < 0.001] were decreased; trabecular number (Tb.N) was lower [1.63/0.63 (median/IQR, Tb.N; 1/mm(-1)), P = 0.012] and trabecular separation (Tb.Sp) [0.626/0.24 (median/IQR, Tb.Sp; mu m), P = 0.038] was higher in irradiated mandibular bone. With higher Dmax, trabecular number increases (Spearman's correlation R = 0.470, P = 0.018) and trabecular separation decreases (Spearman's correlation R = -0.526, P = 0.007). Bone mineral density (BMD, milligrams hydroxyappetite per cubic centimetre, mgHA/cm(3)) [1016/99 (median/IQR, BMD; mgHA/cm(3)), P = 0.03] and trabecular separation [0.739/0.21 (median/IQR, Tb.Sp; mu m), P = 0.005] are higher whereas connectivity density (Conn Dens) [3.94/6.71 (median/IQR, Conn Dens), P = 0.047] and trabecular number [1.48/0.44 (median/IQR, Tb.N; 1/mm(-1)), P = 0.002] are lower in Dmax <= 50 Gy compared to controls.Conclusions: Radiotherapy dramatically impairs bone turnover in the mandible. Deterioration in microarchitecture only affects bone irradiated with a Dmax of <50 Gy. The 50 Gy value seems to be a critical threshold to where the effects of the radiation is more detrimental. (C) 2020 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved. Show less
