Friction of Stainless Steel, Nickel-Titanium Alloy, and Beta-Titanium Alloy Archwires in Two Commonly Used Orthodontic Brackets

Abstract

In orthodontic treatment, the efficiency of tooth movement is affected by the frictional force between the archwire and bracket slot. This study evaluated the static and kinetic frictional forces produced in different combinations of orthodontic archwires and brackets. Three types of archwires [stainless steel, nickel-titanium (NiTi) alloy, and betatitanium (TMA) alloy] and two types of brackets (stainless steel and self-ligating) were tested. Both static and kinetic frictional forces of each archwire-bracket combination were measured 25 times using a custom-designed apparatus. The surface topography and hardness of the archwires were also evaluated. All data were statistically analyzed using two-way analysis of variance and Tukey's test. The experiments indicated that the static frictional force was significantly higher than the kinetic frictional force in all archwire-bracket combinations not involving TMA wire. TMA wire had the highest friction, followed by NiTi wire, and then stainless steel wire when using the stainless steel bracket. However, there was no difference between NiTi and stainless steel archwires when using the self-ligating bracket. For TMA wire, the friction was higher when using the stainless steel bracket than when using the self-ligating bracket. Scanning electron microscopy indicated that stainless steel wire exhibited the smoothest surface topography. The hardness decreased in the order of stainless steel wire > TMA wire > NiTi wire. This study demonstrates that the frictional forces of brackets are influenced by different combinations of bracket and archwire. The reported data will be useful to orthodontists.

A Critical Appraisal of the Use and Properties of Nickel–Titanium Dental Alloys

“…Each of the archwire-bracket combinations has a unique set of physical properties that affect its performance [81]. Frictional force in the archwire-bracket slot combination affects tooth movement [75]. To simulate the load of the wire in service with values in range from 0.196 to 0.98 N, the normal load during experiments should be around 1 N [5].…”

Effect of fine particle shot peening on surface friction of stainless steel and ceramic bracket slots

“…However, it is challenging to determine the actual force because 12-60% of the total force is lost to sliding resistance 2) . Factors of sliding resistance include the materials for the brackets and arch wires 3,4) , surface roughness, sizes of the arch wires 5,6) , angulation and torque between the bracket-arch wire combination, distance between brackets, types of ligations, and the oral environment. When one surface slides over another surface, plastic deformation occurs at the asperities or at the peak of surface irregularities between the two objects, leading to movement resistance due to friction.…”

“…However, it has a high friction coefficient, is brittle, and traumatizes the enamel during bracket removal [10][11][12] . To reduce friction and overall treatment duration, a self-ligating bracket was developed 4,13,14) . However, several studies showed varying results such as an inability to conclude whether these brackets significantly reduce friction and treatment duration 4,15,16) .…”

Frictional Properties of the TiNbTaZrO Orthodontic Wire—A Laboratory Comparison to Popular Archwires

“…In previous studies of frictional resistance of orthodontic wires, TiMo wires generated the highest friction values, followed by NiTi and SS wire, when using the SS brackets [ 16 ]. Another study stated that SS wires performed the least amount of friction, followed by CoCr, NiTi, and β-Ti wires [ 17 ].…”