Korean J Orthod.  2014 Jul;44(4):157-167. 10.4041/kjod.2014.44.4.157.

Comparison of frictional forces between aesthetic orthodontic coated wires and self-ligation brackets

• Kim Y
• Cha JY
• Hwang CJ
• Yu HS
• Tahk SG

• KMID: 2273272
• DOI: http://doi.org/10.4041/kjod.2014.44.4.157

Abstract

OBJECTIVE
The purpose of this study was to evaluate the clinical efficacy of polymer- and rhodium-coated wires compared to uncoated wires by measuring the frictional forces using self-ligation brackets.
METHODS
0.016-inch nickel titanium (NiTi) wires and 0.017 x 0.025-inch stainless steel (SS) wires were used, and the angulations between the brackets and wires were set to 0degrees, 5degrees, and 10degrees. Upper maxillary premolar brackets (Clippy-C(R)) with a 0.022-inch slot were selected for the study and a tensile test was performed with a crosshead speed of 5 mm/min. The maximum static frictional forces and kinetic frictional forces were recorded and compared.
RESULTS
The maximum static frictional forces and the kinetic frictional forces of coated wires were equal to or higher than those of the uncoated wires (p < 0.05). The maximum static frictional forces of rhodium-coated wires were significantly higher than those of polymer-coated wires when the angulations between the brackets and wires were set to (i) 5degrees in the 0.016-inch NiTi wires and (ii) all angulations in the 0.017 x 0.025-inch SS wires (p < 0.05). The kinetic frictional forces of rhodium-coated wires were higher than those of polymer-coated wires, except when the angulations were set to 0degrees in the 0.016-inch NiTi wires (p < 0.05).
CONCLUSIONS
Although the frictional forces of the coated wires with regards to aesthetics were equal to or greater than those of the uncoated wires, a study under similar conditions regarding the oral cavity is needed in order to establish the clinical implications.

Keyword

Wire; Frictional forces; Bracket

MeSH Terms

Bicuspid
Esthetics
Friction*
Mouth
Nickel
Stainless Steel
Titanium
Nickel
Stainless Steel
Titanium

Figure

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  Figure 1 Types of wires (0.016-inch nickel titanium and 0.017 × 0.025-inch stainless steel) and tested bracket. A, Uncoated wire (G&H Orthodontics, Franklin, IN, USA); B, Dany coated arch wire (DANY BMT, Anyang, Korea); C, Sentalloy® and White wire (Tomy Inc., Futaba, Japan); D, maxillary premolar Clippy-C® bracket (Tomy Inc.).

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  Figure 2 Universal testing machine (Instron 5942; Instron Corp., USA). A, Rotation fixture screw; B, inner aluminum block; C, outer aluminum block; D, weight (150 g).

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  Figure 3 Typical graph from the friction test (1 gf = 9.8 mN).

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  Figure 4 Maximum static frictional forces and kinetic frictional forces (1 gf = 9.8 mN). A, Comparison of maximum static frictional forces between the bracket and 0.016-inch nickel titanium (NiTi) wire with different coatings and angulations. B, Comparison of maximum static frictional forces between the bracket and 0.017 × 0.025-inch stainless steel (SS) wire with different coatings and angulations. C, Comparison of kinetic frictional forces between the bracket and 0.016-inch NiTi wire with different coatings and angulations. D, Comparison of kinetic frictional forces between the bracket and 0.017 × 0.025-inch SS wire with different coatings and angulations. Control, Uncoated wires; P group, polymer-coated wires; R group, rhodium-coated wires.

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  Figure 5 Scanning electron micrographs of 0.016-inch nickel titanium wires at 1,000× magnification. A, Uncoated wire; B, polymer-coated wire; C, rhodium-coated wire. 1, New wires before testing; 2, wires after testing; arrows, area with surface damage.

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  Figure 6 Scanning electron micrographs of 0.017 × 0.025-inch stainless steal wires at 1,000× magnification. A, uncoated wire; B, polymer-coated wire; C, rhodium-coated wire. 1, New wires before testing; 2, wires after testing; arrows, area with surface damage.

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  Figure 7 Cross section of a wire in the group of polymer-coated wires.

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