In vitro friction of stainless steel arch wire–bracket combinations in air and different aqueous solutions

Abstract

For all aqueous solutions a lower coefficient of friction was found compared to tests performed in ambient air.

Effect of dental arch convexity and type of archwire on frictional forces

“…Such a reduction might shorten the treatment period and also improve anchorage control. 8 Friction between the bracket and archwire can cause up to 50% loss of force. 4,5,9 As a result, the desired tooth movement is slowed down or even inhibited.…”

“…2,10,11 Frictional resistance must therefore be kept to a minimum during sliding mechanics so that orthodontic tooth movement can be generated through optimal light forces with better patient comfort. 3 The theoretic considerations and clinical implications of friction during sliding in orthodontics demonstrated that this type of force depends on complex variables, such as bracket types (conventional vs. self-ligating), 2,5,8 angulation of archwire to bracket, 12 arch-wire 7 types, 13 dimensions and shape of the slot and the wire, 3,14 ligating force, 8,14 oscillating displacements, 2 repeated use of brackets, 11 and dry and wet environments. 4,15 Furthermore, it was reported that resistance to sliding or friction of an arch-wire-bracket assembly is a combined effect of 3 components namely, classical friction, elastic binding and/or physical notching.…”

“…5,8,15 The materials used can also differ from conventional composite, porcelain, metal brackets 18 to self-ligating ones and to various arch-wires. 3,15 During the last decade, various in-vitro techniques have been used to describe the frictional behaviour of archwire-bracket combinations.…”

“…3,15 During the last decade, various in-vitro techniques have been used to describe the frictional behaviour of archwire-bracket combinations. 7,8,19 The most frequently used in-vitro test set-up was the one developed by Kusy and Whitley. 20 The authors investigated friction between brackets and arch-wires under different environmental and mechanical conditions in a universal testing machine either in the dry or wet state.…”

“…2,8 However, to the authors' knowledge in such set-ups, the convexity of the dental arches with the sequence of brackets from incisors to the molars were not simulated. The information derived from flat models remains limited since the dental arches present convexity to some extend at some parts of the arches.…”