Evaluation of frictional forces between brackets of different types at various angulations and an arch wire: With and without pulsating vibration

Objective: The objective of this study was to determine the effect of pulsating vibration on the sliding resistance between orthodontic brackets and stainless steel wires. Brackets were placed at two different angulations (0° and 5°) to simulate leveling of a tipped tooth during tooth movement. Pulsating vibration was delivered via the AcceleDent device. Background: Friction is defined as a force that retards or resists the relative motion of two objects in contact, and its direction is tangential to the common boundary of the two surfaces in contact. This has been of interest to the orthodontist since the mid-20th century. Since the time of Stoner’s paper in 1960, the orthodontic literature has been full of studies done on friction in orthodontics including: friction with different ligation methods, friction among different arch wire materials, friction and different bracket materials, and friction with various slot designs. Understanding friction has led to the emergence of new technologies in orthodontics. One of the most popular is the self-ligating bracket. This popularity arose from claims that they reduce friction during treatment. Other innovations have been introduced in the field of orthodontics to help accelerate tooth movement. Among these innovations is the application of a pulsating vibration during active orthodontic treatment. Such pulsating vibration can be delivered during orthodontic treatment by AcceleDent, which is a hands- free device designed by OrthoAccel Technologies, Inc., Bellaire, TX. The company claims the output force helps accelerate bone turnover. The following study investigated whether it could decrease treatment time via a different mechanism: decreasing frictional resistance to tooth movement along the arch wire. Methods: A paper template was made of a typodont tooth with a bracket window cut out. The bracket cut out was made with the bracket window angulated 0° and 5°. 0.022” x 0.028” standard prescription edgewise brackets (American Orthodontics, Sheboygan, WI) of ceramic, twin and self-ligating design were bonded to 3 maxillary 1st premolar typodont teeth using the template. The teeth were leveled with a 0.019” x 0.025” SS arch wire and placed in a metal scaffold. They were held in place with Aquasil Ultra XLV wash material PVS (DENTSPLY Caulk, Milford, DE.). Only the middle bracket was adjusted for angulation and accuracy was checked with the iPhone 6 level. The AcceleDent Aura device (OrthoAccel Technologies, Inc., Bellaire, TX). was attached to the occlusal surface of the teeth via cable ties. The AcceleDent Aura device provided 30 Hz of pulsating vibration. All tests were performed with a 0.019” x 0.025” SS arch wire pulled through the brackets via a Universal Testing Machine (Instron, Grove City, PA) at a crosshead speed of 2.5mm/min for 30 seconds. Frictional resistance was measured by averaging 6 recordings every 5 seconds. Results: The pulsating vibration provided by the AcceleDent device significantly reduced the resistance to sliding for each bracket type at both 0° and 5° (p\u3c0.05). Ceramic brackets had the highest resistance to sliding of all bracket types. Conclusions: Pulsating vibration via the AcceleDent Aura device reduces the resistance to sliding between a bracket and arch wire in vitro. This may potentially decrease overall treatment time but more in vivo studies need to be done to evaluate this

How is space public? Implications for spatial policy and democracy

Battles over public space involve conflicts of values that express themselves in planning policies as well as the built environment. However, the dominant conceptions of public space in planning practice and the academic literature supports a limited range of those values. This article argues that conceptions based on openness and accessibility play into a particular construction of public life that emphasises casual interactions and downplays purposive, political ones. Following a conceptual analysis of the public/private distinction, the paper offers a novel, threefold account of public space; argues that democracy requires a particular kind of publicness not recognized by the commonly-accepted definition; and deploys a simple content analysis to highlight the conceptual emphases and absences in planning policy in the political heart of London. It argues that some advocates of public space are unwittingly supporting restrictive planning and design practices that limit important kinds of democratic expression

5-Lypoxygenase Products Are Involved in Renal Tubulointerstitial Injury Induced by Albumin Overload in Proximal Tubules in Mice

The role of albumin overload in proximal tubules (PT) in the development of tubulointerstitial injury and, consequently, in the progression of renal disease has become more relevant in recent years. Despite the importance of leukotrienes (LTs) in renal disease, little is known about their role in tubulointerstitial injury. The aim of the present work was to investigate the possible role of LTs on tubulointerstitial injury induced by albumin overload. An animal model of tubulointerstitial injury challenged by bovine serum albumin was developed in SV129 mice (wild-type) and 5-lipoxygenase-deficient mice (5-LO(-/-)). The changes in glomerular morphology and nestin expression observed in wild-type mice subjected to kidney insult were also observed in 5-LO(-/-) mice. The levels of urinary protein observed in the 5-LO(-/-) mice subjected or not to kidney insult were lower than those observed in respective wild-type mice. Furthermore, the increase in lactate dehydrogenase activity, a marker of tubule damage, observed in wild-type mice subjected to kidney insult did not occur in 5-LO(-/-) mice. LTB4 and LTD4, 5-LO products, decreased the uptake of albumin in LLC-PK1 cells, a well-characterized porcine PT cell line. This effect correlated with activation of protein kinase C and inhibition of protein kinase B. The level of proinflammatory cytokines, tumor necrosis factor-α and interleukin (IL)-6, increased in mice subjected to kidney insult but this effect was not modified in 5-LO(-/-) mice. However, 5-LO(-/-) mice subjected to kidney insult presented lower macrophage infiltration and higher levels of IL-10 than wild-type mice. Our results reveal that LTs have an important role in tubulointerstitial disease induced by albumin overload