Aging/*physiology ; *Biocompatible Materials ; Bone Regeneration/physiology ; Bone Remodeling/physiology ; Facial Bones/physiopathology ; Facial Bones/*surgery ; Maxillofacial Development/*physiology ; *Prostheses and Implants

Aging of craniofacial skeleton significantly impairs the repair and regeneration of trauma-induced bony defects, and complicates dental treatment outcomes. Age-related alveolar bone loss could be attributed to decreased progenitor pool through senescence, imbalance in bone metabolism and bone-fat ratio. Mesenchymal stem cells isolated from oral bones (OMSCs) have distinct lineage propensities and characteristics compared to MSCs from long bones, and are more suited for craniofacial regeneration. However, the effect of epigenetic modifications regulating OMSC differentiation and senescence in aging has not yet been investigated. In this study, we found that the histone demethylase KDM4B plays an essential role in regulating the osteogenesis of OMSCs and oral bone aging. Loss of KDM4B in OMSCs leads to inhibition of osteogenesis. Moreover, KDM4B loss promoted adipogenesis and OMSC senescence which further impairs bone-fat balance in the mandible. Together, our data suggest that KDM4B may underpin the molecular mechanisms of OMSC fate determination and alveolar bone homeostasis in skeletal aging, and present as a promising therapeutic target for addressing craniofacial skeletal defects associated with age-related deteriorations.
Aging ; Cell Differentiation ; Facial Bones/physiology* ; Humans ; Jumonji Domain-Containing Histone Demethylases/genetics* ; Mesenchymal Stem Cells/cytology* ; Osteogenesis ; Osteoporosis

Biomechanical Phenomena ; Bone Substitutes ; therapeutic use ; Child ; Facial Bones ; physiology ; Fracture Fixation, Internal ; Fracture Healing ; Humans ; Skull ; physiology ; Skull Fractures ; therapy ; Stress, Mechanical

PURPOSE: There are marked differences in facial skeletal characteristics between Asian and Caucasian. However, ethnic differences in age-related facial skeletal changes have not yet been fully established. The aims of this study were to evaluate age-related changes in Asian midfacial skeletons and to explore ethnic differences in facial skeletal structures with aging between Caucasian and Asian. MATERIALS AND METHODS: The study included 108 men (aged 20-79 years) and 115 women (aged 20-81 years). Axial CT images with a gantry tilt angle of 0 were analyzed. We measured three-dimensional (3D) coordinates at each point with a pixel lens cursor in a picture archiving and communication system (PACS), and angles and widths between the points were calculated using 3D vector mathematics. We analyzed angular changes in 4 bony regions, including the glabellar, orbital, maxillary, and pyriform aperture regions, and changes in the orbital aperture width (distance from the posterior lacrimal crest to the frontozygomatic suture) and the pyriform width (between both upper margins of the pyriform aperture). RESULTS: All 4 midfacial angles in females and glabellar and maxillary angles in males showed statistically significant decreases with aging. On the other hand, the orbital and pyriform widths did not show statistically significant changes with aging. CONCLUSION: The results of this study suggest that Asian midfacial skeletons may change continuously throughout life, and that there may be significant differences in the midfacial skeleton between both sexes and between ethnic groups.
Adult ; Aged ; Aging/ethnology/*physiology ; Asian Continental Ancestry Group ; Facial Bones/*anatomy & histology/*radiography ; Female ; Humans ; Image Processing, Computer-Assisted ; Male ; Mathematics ; Maxilla/anatomy & histology/radiography ; Middle Aged ; Orbit/anatomy & histology/radiography ; Radiology Information Systems ; Republic of Korea ; Tomography, X-Ray Computed/*methods ; Young Adult ; Zygoma/anatomy & histology/radiography