The aim of this study was to compare the static and kinetic frictional forces generated by various contemporary designs of self-ligating brackets (SLBs) and different wire alloys. In total, six different brackets (four passive type SLB, one active SLB, and one conventional bracket) were investigated using stainless steel, nickel-titanium, and titanium-molybdenum alloy archwires of several sizes...

A bracket has been designed to allow a Kowa RC II fundus camera to be mounted firmly on a Haag-Streit goo slit lamp. The bracket provides a steady support which is of particular importance in fluorescein fundus angiography. The bracket consists oftwo parts. The upper part of mild steel and finished in satin chrome fits into the camera shoe and can be locked into place. The lower part is black a...

There is every indication that classical friction controls sliding mechanics below some critical contact angle, theta c. Once that angle is exceeded, however, binding and notching phenomena increasingly restrict sliding mechanics. Using geometric archwire and bracket parameters, the theta c is calculated as the boundary between classical frictional behaviour and binding-related phenomena. What ...

OBJECTIVES Providing reliable attachment between bracket base and zirconia surface is a prerequisite for exertion of orthodontic force. The purpose of the present study was to evaluate the effect of four zirconium surface treatment methods on shear bond strength (SBS) of orthodontic brackets. MATERIALS AND METHODS One block of zirconium was trimmed into four zirconium surfaces, which served a...

OBJECTIVE The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments. MATERIALS AND METHODS Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA). Subsequently in first group, ceramic primer and...

We explain a general approximation technique for nonholonomic systems by discussing in detail a special example, chosen so as to illustrate some of the technical aspects of the general construction. The example considered is that of an extension of a two-input system obtained by adding a single bracket of degree ve. This bracket is suuciently complicated to exhibit some phenomena, such as multi...

In this paper we consider the optimal structure of double bracket flows and generalisations of these flows to more complex gradient flows. We discuss different notions of optimality and the relationship of the flows to the structure of convex polytopes.