Variations in bone density across the body of the immature human mandible

Abstract

During growth the mandible accommodates increases in biomechanical loading resulting from changes in the function of structures of the oral cavity. Biomechanical loads are thought to play an intricate and vital role in the modelling and remodelling of bone, with site-specific effects on bone mineral density. It is anticipated that the effects of this loading on bone mineral density are intensified during the functional transition from prenatal to postnatal stages. The aim of this study was thus to evaluate changes in bone mineral density across the body of the immature human mandible during the early stages of dental development. The study sample included 45 human mandibles, subdivided into three age groups: prenatal (30 gestational weeks to birth; n = 15); early postnatal (birth to 12 months; n = 18); and late postnatal (1-5 years; n = 12). Mandibles were scanned using X-ray micro-computed tomography. Eight landmarks were selected along the buccal/labial and lingual surfaces of each dental crypt for evaluation of the bone mineral density. Bone mineral density values were calculated using a reference standard and analysed using multivariate statistics. The bone mineral density of the lingual surface was found to be significantly higher (P ≤ 0.000) than that of the buccal/labial surface. Furthermore, bone mineral density in the alveolar region of the buccal/labial surface of the deciduous central incisor (P ≤ 0.001), the deciduous first molar (P ≤ 0.013) and lingual alveolar area of the deciduous second molar (P ≤ 0.032) were significantly greater in the early postnatal period than in the prenatal period. While changes in bone mineral density across the lingual surface were consistent with the progression of development and the biomechanical demand of the tongue as previously demonstrated, changes observed across the buccal/labial surface of the mandible appeared to accompany the advancing dental development. Thus, changes in bone mineral density across the mandible appear to be reflective of the stage of dental development and the level of biomechanical loading.

Micro-Architecture Study of the Normal Infant Auditory Ossicles with Micro-Computed Tomography

“…Micro-CT can accurately measure the size of each anatomical structure of the auditory ossicles, and analyze the 3D shape of the ossicular chain from multiple angles and multi-planes through 3D reconstruction. This facilitates the positioning of the auditory ossicles, guides the effective and reasonable articulation of ossicular replacement prosthesis, and improves the movement of the tympanic membrane and ossicular chain (Cunningham & Black, 2013;Fallon et al, 2014;Hutchinson et al, 2017;Zdilla et al, 2018). In future research, a microscopic 3D finite element model created from micro-CT images and digital 3D printing can be used for sonodynamic calculation and analysis of normal auditory ossicles and ossicular replacement prosthesis of different materials, in order to investigate the factors affecting hearing restored in patients with conductive deafness (Gentil et al, 2014).…”

Bone mineral density of human ear ossicles: An assessment of structure in relation to function

“…The ossicles were mounted on foam to eliminate the possibility of movement during the scanning process. The bones were scanned in conjunction with a reference material (Hutchinson et al, ), as a means of standardizing all bone mineral density measurements across the sample. The specimens were placed on a rotating platform which enabled scanning of the sample in 360° with 1,000 projections.…”

“…Associated with the ossicles are ligaments and tendons, which may have a biomechanical influence on the remodeling of the bone as occurs at other sites in the body (Mavropoulos et al, ; Ruffoni et al, ; Hutchinson et al, ). The ossicular ligaments and the tendons of tensor tympani and stapedius contribute to the normal biomechanical conduction of sound across the middle ear (Lemmerling et al, ).…”

Densitometric assessment in the justification of rehabilitation of patients with atrophy of the bone tissue of the mandible, on the right side

“…To understand and assess the bone tissue of the jaws [7], the authors recommend a study of bone density with the inclusion of cortical and trabecular layers [26], changes in which can be valuable indicators of its biomechanical potential, as described in these works [17,22].…”