The Effects of Silver Coating on Friction Coefficient and Shear Bond Strength of Steel Orthodontic Brackets VALIOLLAH ARASH, 1,2 KEIVAN ANOUSH, 3 SAYED MAHMOOD RABIEE, 4 MANUCHEHR RAHMATEI, 2 AND SAEID TAVANAFAR 5 1 Dental Research Center, Babol University of Medical Sciences, Babol, Iran 2 Department of Orthodontics, School of Dentistry, Babol University of Medical Sciences, Babol, Iran 3 Department of Orthodontics, School of Dentistry, Babol University of Medical Sciences, Babol, Iran 4 Department of Materials Engineering, Faculty of Mechanical Engineering, Babol University of Technology, Babol, Iran 5 General Dental Practitioner, Private Practice, Shiraz, Iran Summary: Aims of the present study was to measure frictional resistance between silver coated brackets and different types of arch wires, and shear bond strength of these brackets to the tooth. In an experimental clinical research 28 orthodontic brackets (standard, 22 slots) were coated with silver ions using electroplate method. Six brackets (coated: 3, uncoated: 3) were evaluated with Scanning Electron Microscopy and Atomic Force Microscopy. The amount of friction in 15 coated brackets was measured with three different kinds of arch wires (0.019 Â 0.025-in stainless steel [SS], 0.018-in stainless steel [SS], 0.018-in Nickel-Titanium [Ni-Ti]) and compared with 15 uncoated steel brackets. In addition, shear bond strength values were compared between 10 brackets with silver coating and 10 regular brackets. Universal testing machine was used to measure shear bond strength and the amount of friction between the wires and brackets. SPSS 18 was used for data analysis with t-test. SEM and AFM results showed deposition of a uniform layer of silver, measuring 8–10 mm in thickness on bracket surfaces. Silver coating led to higher frictional forces in all the three types of arch wires, which was statistically significant in 0.019 Â 0.025-in SS and 0.018-in Ni-Ti, but it did not change the shear bond strength significantly. Silver coating with electroplating method did not affect the bond strength of the bracket to enamel; in addition, it was not an effective method for decreasing friction in sliding mechanics. SCANNING 37:294–299, 2015. © 2015 Wiley Periodicals, Inc. Key words: Dentistry, Friction, Metal Coatings, Sliding, Steel brackets Introduction Orthodontic treatments are associated with tooth movements. One of the common techniques in this field is sliding the tooth on wires, which has advantages such as a decrease in clinical treatment time, patient comfort, and control of tooth movement in three dimensions. However, one of the important problems of this method is friction between the wire and bracket (Shames, ’96). Silver metal or ions have been known historically for their potent antibacterial effects (Kang et al., 2000). Materials containing silver are chemically stable and release silver ions for a long period (Toshikazu, ’99). Long-lasting antimicrobial effects, temperature stability, and low volatility of silver particles are some of the facts that promoted renewed interest in use of silver particles as antimicrobial agents (Kumar and Munstedt, 2005). The growing numbers of antibiotic-resistant bacterial strains are less likely to develop resistance against silver particles (Pal et al.,2007; Stobie et al.,2008). The antibacterial effect of silver has been shown against gram-positive bacteria, gram-negative bacteria, fun- goids, protozoa, and particular viruses in an extended spectrum (Monteiro et al.,2009; Ryu et al.,2011; Morita et al.,2014). Radial diffusion test method has shown promising antibacterial results of silver coating of orthodontic wires against different bacterial strains (Morita et al.,2014). There are different methods to deposit and form thin layers of silver in medicine and dentistry, such as physical vapor deposition (PVD; Ryu et al., 2011), sol/gel method Address for reprints: Dr. Sayed Mahmood Rabieer, Department of Materials Engineering, Faculty of Mechanical Engineering, Babol University of Technology, P.O. Box: 484, Babol, Iran. E-mail: rabiee@nit.ac.ir Received 26 December 2014; revised 28 February 2015; Accepted with revision 10 March 2015 DOI: 10.1002/sca.21212 Published online 21 May 2015 in Wiley Online Library (wileyonlinelibrary.com). SCANNING VOL. 37, 294–299 (2015) © Wiley Periodicals, Inc.