Comparative Evaluation of Frictional Resistance Between Different Types of Ceramic Brackets and Stainless Steel Brackets With Teflon-Coated Stainless Steel and Stainless Steel Archwires: An In-Vitro Study

Abstract

Background Orthodontic tooth movement relies on sliding mechanics usually achieved by sliding the archwire through brackets. Sliding causes friction which is a force resisting the relative motion of two contacting objects. Frictional resistance is undesirable in orthodontic tooth movement because the archwire might bind with the bracket and prevent tooth movement. In addition, friction causes bending of the archwire leading to unwanted tooth movement or space loss through anchorage interference, prolonging the treatment time and root resorption. This study was performed to compare the frictional resistance produced by different types of ceramic brackets and stainless steel brackets with Teflon-coated stainless steel and stainless steel archwires. The surface texture of the wire before and after friction test was also evaluated using a scanning electron microscope (SEM). Methodology A total of 48 samples were tested. In total, 12 premolar brackets each of stainless steel (Ortho technology, Carlsbad, CA, USA), monocrystalline ceramic (Ortho technology, Carlsbad, CA, USA), polycrystalline ceramic (Ortho technology, Carlsbad, CA, USA), and ceramic bracket with a metal slot (Ortho technology, Carlsbad, CA, USA) having an 0.022-inch slot were coupled with 0.019 × 0.025-inch stainless steel and Teflon-coated stainless steel wires. Each bracket-wire assembly was vertically mounted and clamped to the jaws of the universal testing machine. The wire was pulled across the bracket with a cross head speed of 10 mm per minute. The readings obtained were recorded. To evaluate the surface roughness, wires were examined using an SEM (in four magnifications 250×, 500×, 1,000×, and 5,000×) before and after testing. Results Under the testing conditions, the stainless steel bracket-stainless steel wire combination produced the least frictional resistance, and the polycrystalline ceramic bracket-stainless steel wire combination produced the highest frictional resistance. Ceramic brackets with a metal slot generated lesser friction than other types of ceramic brackets but more friction than stainless steel brackets. Moreover, for all bracket-archwire combinations, Teflon-coated wires generated reduced frictional resistance compared to stainless steel wires. The surface examination of Teflon-coated stainless steel wire and conventional uncoated stainless steel wire revealed that Teflon-coated wire had a smoother surface compared to uncoated stainless steel wire. Conclusions Within the limitations of this study, it was concluded that the stainless steel bracket produced the lowest frictional resistance and the polycrystalline ceramic bracket produced the highest frictional resistance. Ceramic brackets with a metal slot showed a coefficient of friction that was more than but comparable to that of stainless steel brackets. Monocrystalline ceramic brackets generated lesser friction compared to polycrystalline ceramic brackets. Further, Teflon coating of stainl...

Functional Surface Coatings on Orthodontic Appliances: Reviews of Friction Reduction, Antibacterial Properties, and Corrosion Resistance

“…However, it is difficult to find a single coating that can satisfy all three conditions at the same time. A few coatings, such as TaAgB and PTFE, offer relatively comprehensive performance improvements [ 68 , 92 , 97 , 147 , 192 ]. However, studies on these materials are scarce, and there is not enough clear and stable clinical evidence.…”

“…Teflon (polytetrafluoroethylene (PTFE)), an aesthetic white coating for dental instruments, has been shown to provide a smoother surface and reduce frictional resistance and frictional damage [ 35 , 36 , 37 , 38 , 39 ] on NiTi [ 91 ] or SS archwires [ 92 ]—especially when paired with metal slots in ceramic brackets [ 38 ]—in both dry and wet conditions. However, when combined with ceramic brackets, PTFE- and epoxy-coated NiTi archwires will increase the friction between the archwires and the brackets [ 93 ].…”

“…Another research shows the contrast, which whether combined with ceramic or metal brackets, PTFE-, or epoxy-coated SS archwires always show higher friction resistance [ 94 ]. However, the latest study by K. Ranjan and R. Bhat et al contradicts this finding; the study concludes that whether paired with SS brackets, ceramic brackets, or ceramic brackets with metal slots, the PTFE-coated archwire produces lower frictional resistance compared to uncoated SS archwires [ 92 ]. In addition, research has investigated suitable preparation conditions.…”

“…CTS coatings can replace ZnO and are relatively more convenient and cost-effective, as they do not require coating on both the archwire and the bracket surface [ 24 ]. Aesthetic coatings such as PTFE are suitable for both SS and NiTi archwires, but when used with ceramic brackets, it is better to choose ceramic brackets with metal slots [ 92 ] and other commonly used polymeric aesthetic archwires. Among the other common aesthetic polymer coatings on the market, only epoxy shows a stronger friction reduction effect than PTFE [ 97 ].…”

Assessment of the influence of metal ions released from the fixed orthodontic appliances on the static friction and surface topography of stainless steel and I archwires: An in-vitro study

“…Stainless steel wire was employed in this study due to its superior characteristics, including the least frictional resistance, minimal surface roughness, lowest frictional coefficient, and sliding resistance compared to other materials, such as NiTi. [ 31 32 ] Researchers have always considered SS material the standard and reference to judge and compare the properties of new archwires (I archwire) in the field. [ 6 ] In previous studies that used a universal Instron machine, this machine was generally accepted as the standard and conventional method for testing the resistance to sliding.…”