Frictional resistance of ceramic and stainless steel orthodontic brackets

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

“…Tselepis et al 5 reported that lubrication with artificial saliva resulted in significantly lower frictional values than when tested in dry conditions and this finding was valid for nearly all bracket/arch-wire combinations studied. Pratten et al 4 controversially, reported that saliva substitute increased the static friction for all combinations tested. Anderson and Quevedo, 17 however found that saliva played an insignificant role in 12 frictional forces when the wire surfaces and the bracket slots were lubricated with this medium.…”

“…4,5,8,15 Lubricants to overcome friction are not always thin and therefore in this study the frictional forces were measured in the wet state. Artificial saliva as a lubricant may best simulate the situation in the oral milieu.…”

“…4,5 The resistance to friction is characterized as either static or kinetic. Static friction is the force required to produce the initial movement and it is always stronger than the kinetic force that keeps the body in motion.…”

“…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. Frictional resistance during orthodontic treatment is a key factor in determining the force systems required for moving the teeth.…”

“…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. 16 On the other hand, the deformation amount of the arch-wire is dependant on the applied force and the elasticity of the wire.…”