ABSTRACT
@#In the process of orthodontic treatment, the balance between the modeling of alveolar bone and the mechanical stress exerted by the appliance is key to the effective movement of orthodontic teeth. Alveolar bone modeling involves many regulatory factors, and microRNAs (miRNAs), as posttranscriptional regulatory factors, play an important role in the occurrence of bone modeling. As an important member of the miRNA family, miRNA-21 promotes the differentiation of periodontal ligament stem cells into osteoblasts and plays an important role in maintaining bone balance and preventing bone resorption as a regulator of osteoclast formation and a promoter of osteoclast differentiation. A literature review showed that miRNA-21 can regulate osteoclast function and promote bone resorption through programmed cell death 4 (PDCD4), phosphate and tension homology deleted on chromosome ten (PTEN), receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG). MiRNA-21 is highly sensitive to external mechanical stress in the process of orthodontic tooth movement. After orthodontic force is applied, miRNA-21 can promote osteoclast formation and accelerate orthodontic movement; through targeted regulation of periodontal ligament associated protein-1 (PLAP-1), it can regulate periodontal ligament remodeling in the late stage of tooth movement and improve the potential of tooth movement. In addition, miRNA-21 mediates orthodontic tooth movement (OTM) and alveolar bone remodeling in the periodontal inflammatory microenvironment. miRNA-21 can upregulate the expression of hypoxia-inducible factor-1α (HIF-1α) in periodontal ligament stem cells in a hypoxic environment. It can promote the expression of osteogenic markers, such as osteopontin (OPN), osteocalcin (OCN), alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2), and promote osteogenic differentiation during orthodontic tooth movement.
ABSTRACT
Abstract: Background: Histomorphometric analysis of bone samples is a key tool for studying bone metabolism; however, only a few pediatric reference data exist. The aim of the present study is to report more reference data and to investigate if histomorphometric differences exist between age and gender. Methods: We obtained 19 transiliac bone samples previously marked with tetracycline, from children between 8 and 17 years (13 were male), with normal blood test results and urine biochemical bone markers. We evaluated bone histomorphometric parameters using a digitalizing table with osteomeasure to obtain normative data of means and standard deviations, as well as median and range. Due to the small sample, a Monte Carlo simulation was applied. Structural, static, dynamic, and resorptic histomorphometric parameters were evaluated by age and gender following the American Society for Bone and Mineral Research recommendations. Results: Bone volume (in the older children) and mineral apposition rate (in the younger children), the eroded surface (in boys), and the new bone wall thickness (in girls) were significantly increased. On the trabecular area of mineralization front, the modeling and the remodeling bone formation were similar (16 and 18%). The rest of the histomorphometric bone parameters by age and gender showed no significant difference. Conclusion: In healthy children, these bone histomorphometric findings, with these techniques and for this ages could be used as reference values.
Resumen: Introducción: El análisis histomorfométrico del tejido óseo para el estudio de las enfermedades metabólicas óseas, cuando se correlacionan los hallazgos clínicos, sigue siendo la herramienta con mayor sensibilidad y especificidad para la mayoría de los diagnósticos. En los niños existen pocos reportes histomorfométricos del tejido óseo metabólico normal, por lo que nuestro propósito es reportar más datos de referencia e investigar si hay diferencias histomorfométricas entre edades y sexos. Métodos: Estudio realizado en 19 niños de 8 a 17 años (13 masculinos) sin anomalías clínicas ni bioquímicas evidentes. Se tomaron muestras de tejido óseo transilíaco marcadas con tetraciclina. Se obtuvieron medias, desviaciones y rangos histomorfométricos totales, y correlación por edad y sexo, siguiendo las recomendaciones para la histomorfometría de la American Society for Bone and Mineral Research. Se realizó una simulación Montecarlo. Resultados: El volumen óseo (en niños mayores), la velocidad de agregación del mineral (en niños menores), la erosión trabecular periférica (en niños) y el grosor de la pared ósea nueva (en niñas) exhibieron aumentos significativos. En el área trabecular del frente de mineralización, el modelado y el remodelado de la formación ósea fueron similares (16 y 18%). El resto de los parámetros histomorfométricos óseos no mostraron diferencias significativas. Conclusiones: Estos hallazgos histomorfométricos del tejido óseo de niños normales con estas técnicas y para estas edades pueden ser utilizados como valores de referencia.
Subject(s)
Adolescent , Child , Female , Humans , Male , Bone and Bones/metabolism , Bone Density/physiology , Bone Remodeling/physiology , Reference Values , Biopsy , Sex Factors , Age Factors , IliumABSTRACT
Virtual reality technology and force feedback technology are novel human-machine interaction technologies. The virtual surgery simulation training system combined with these two technologies provides a new method for orthopedic surgery training, which can improve the training efficiency,thereby reducing the training costs and shortening the growth cycle of young orthopedic surgeons. In recent years, the virtual drilling bone surgery simulation technology have been researched broadly and obtained a preliminary application. In this paper, the existing research statusof virtual bone drilling operation depended on visuo-haptic techniques were studied, classified and summarized, the main content focused on three key techniques: bone modeling, drilling bone force prediction model and tactile simulation, and then analyzed the advantages and disadvantages of existing methods. Finally,some perspectives for related technology development trend of the virtual simulation bone drilling surgery in future was pointed out.