China experts' consensus on preventive and interceptive orthodontic treatments of malocclusions of children / 华西口腔医学杂志

Malocclusion is one of the three most common oral diseases reported by World Health Organization(WHO). In China, its incidence rate is rising. Malocclusion seriously affects the dental and maxillofacial function, facial appearance and growth development of nearly 260 million children in China, and what is more, it affects their physical and mental health development. Malocclusion occurrence is related to genetic and environmental factors. Early treatment of malocclusion can create a good dental and maxillofacial development environment, correct abnormal growth and control the adverse effects of abnormal genetic factors. It can effectively reduce the prevalence of children's malocclusion and enhance their physical and mental health. This is an urgent need from the economic perspective of our society, so it has great practical and social significance. Experts from the project group "standard diagnose and treatment protocols for early orthodontic intervention of malocclusions of children" which initiated by China National Health Institute of Hospital Administration wrote the "China Experts' Consensus on Preventive and Interceptive Orthodontic Treatments of Malocclusions of Children", which aims to guide and popularize the clinical practice, improve the clinical theory and practice level, and accelerate the disciplinary development of early treatment of children's malocclusion in China. The consensus elaborates the harmfulness of malocclusion and the necessity of early treatment, and brings up the principles and fundamental contents. Based on the law of dental and maxillofacial development, this paper puts forward the guiding suggestions of preventive and interceptive treatments in different stages of dental development ranging from fetus to early permanent dentition. It is a systematic project to promote and standardize the early treatment of malocclusion. Through scientific and comprehensive stratified clinical practice and professional training, the clinical system of early treatment of malocclusion in China will eventually be perfected, so as to comprehensively care for children's dental and maxillofacial health, and improve their oral and physical health in China.

Coupling of osteogenesis and angiogenesis in bones / 中国组织工程研究

BACKGROUND:In addition to a conduit system for oxygen,nutrients and waste products,blood vessels in bones manipulate multiple aspects of bone formation and provide niches for bone marrow hematopoietic stem cells.Coupling of osteogenesis and angiogenesis plays a crucial role in bone development,maturation,ageing and diseases.OBJECTIVE:To review the architecture of bone vasculature and process of angiogenesis,and then discuss the factors regulating coupling of osteogenesis and angiogenesis.METHODS:CBM and PubMed databases were retrieved using the keywords of "osteogenesis,blood vasculature,angiogenesis" in Chinese and English,respectively.High-quality articles related to the blood vasculature and angiogenesis in bones were included,and the repetitive studies were excluded.Finally 65 eligible articles were included to explore the coupling of osteogenesis and angiogenesis.RESULTS AND CONCLUSION:The formation and stabilization of the skeletal system rely on the coordination of several different types of cellular activities,especially endothelial cells as an important source of signals that regulate chondrocytes and osteogenesis-related cells,thus allowing the coupling of angiogenesis and osteogenesis during development and regeneration.Like other organs,the vascular system in the bones exhibits a typical hierarchy;the arterial trunk branches flow into the capillary network and then converge into the large veins in the center of the bone.Vascular endothelial growth factor,fibroblast growth factor 2,platelet-derived growth factor,matrix metalloproteinases,hypoxia,and Notch signaling pathway are involved in the angiogenesis in bones.The signaling pathways and related cytokines regulating the coupling of osteogenesis and angiogenesis will provide a new treatment strategy to battle bone diseases such as osteoporosis,bone tumor,bone fracture and bone repair.

Expression analysis of α-smooth muscle actin and tenascin-C in the periodontal ligament under orthodontic loading or in vitro culture / 国际口腔科学杂志·英文版

α-smooth muscle actin (α-SMA) and tenascin-C are stress-induced phenotypic features of myofibroblasts. The expression levels of these two proteins closely correlate with the extracellular mechanical microenvironment. We investigated how the expression of α-SMA and tenascin-C was altered in the periodontal ligament (PDL) under orthodontic loading to indirectly reveal the intrinsic mechanical microenvironment in the PDL. In this study, we demonstrated the synergistic effects of transforming growth factor-β1 (TGF-β1) and mechanical tensile or compressive stress on myofibroblast differentiation from human periodontal ligament cells (hPDLCs). The hPDLCs under higher tensile or compressive stress significantly increased their levels of α-SMA and tenascin-C compared with those under lower tensile or compressive stress. A similar trend was observed in the tension and compression areas of the PDL under continuous light or heavy orthodontic load in rats. During the time-course analysis of expression, we observed that an increase in α-SMA levels was matched by an increase in tenascin-C levels in the PDL under orthodontic load in vivo. The time-dependent variation of α-SMA and tenascin-C expression in the PDL may indicate the time-dependent variation of intrinsic stress under constant extrinsic loading.

Effect of loop configuration on appliance stiffness of stainless steel round wire / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of loop configuration on appliance stiffness of stainless steel round wire.</p><p><b>METHODS</b>Some stainless steel round wires with various cross-sectional dimension (0.36, 0.41, 0.46 mm) were selected. Box loops, double horizontal loops, and double vertical loops were manufactured according to established parameters, and loading experiments were carried out with a micro-orthodontic archwire testing apparatus.</p><p><b>RESULTS</b>When the cross-sectional dimension and the span were identical, the appliance stiffness of the box loops, double horizontal loops, and double vertical loops increased successively.</p><p><b>CONCLUSION</b>Configuration of loops exert a great influence on appliance stiffness, and the mechanical properties of box loop are optimal. The force generated by box loop was lighter, slowly decreasing, and easier to be controlled. The activation range of box loop (0.41 mm) was appropriate when the produced optimal moment was between 0.01-0.02 N.m. Box loop (0.41 mm) is preferred to rectify the individual tooth with mild or moderate mesiodistal displacement.</p>

The properties of different orthodontic rectangular arch wires in torsion / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the properties of orthodontic rectangular arch wires in torsion.</p><p><b>METHODS</b>By using the torsion measurement apparatus, torsion moments and angles of four kinds of orthodontic wires (0.46 mm x 0.63 mm and 0.48 mm x 0.63 mm stainless steel wires, and the same size nickel-titanium wires) were tested respectively in a 0.56 mm-slot first maxillary incisor bracket. According to the torsion moments and angles, scatter graphs were drawn to fit the load-deflection curves of four kinds of wires and their linear equations were calculated. According to the equations, the torsion stiffness and the play angles of the wires at 20 N mm correspondingly were calculated.</p><p><b>RESULTS</b>The torsion stiffness of four kinds of wires were 4.909, 6.417, 1.325 and 1.363 N mn/degrees, the torsion angles of different wires were 19.14 degrees, 15.33 degrees, 36.83 degrees and 35.07 degrees at 20 N mm respectively.</p><p><b>CONCLUSION</b>The torsion stiffness of stainless steel wires was bigger than that of the same cross-section dimensional nickel-titanium wires. The difference of torsion stiffness between two dimensional nickel-titanium wires is smaller, while the difference of torsion stiffness between two stainless steel wires is larger.</p>

Bending mechanical properties of NiTi round wire / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the bending mechanical properties and provide reference for orthodontists to select the proper wires during alignment stage.</p><p><b>METHODS</b>In order to analyze the load deflection rate of NiTi round wire quantitatively, some NiTi round wires of different cross-sectional dimension (0.36, 0.41, 0.46 mm) were selected. Then loading-unloading experiments were carried out with the micro-orthodontic archwire testing apparatus and double end bending test could be accomplished with the wire in a 0.56 mm x 0.71 mm standard incisor edgewise bracket slot.</p><p><b>RESULTS</b>Under the load of 0.03 N.m, 0.36 and 0.41 mm NiTi round wire showed excellent super-elasticity, while 0.46 mm NiTi round wire didn't. When the optimal moment produced by the archwire was between 0.01 N.m and 0.02 N.m, the bending range of 0.36, 0.41 and 0.46 mm NiTi round wires was from 21.0 degrees to 49.5 degrees , 7.2 degrees to 23.7 degrees , and 6.5 degrees to 9.5 degrees , respectively after deducting the contact angle.</p><p><b>CONCLUSIONS</b>On the premises of yielding effective orthodontic force, the preferable NiTi round wire for alignment was the one which could produce continuous and slowly declining force.</p>