32 Trends Biomater. Artif. Organs, 28(1), 32-36 (2014) http://www.sbaoi.org/tibao An Overview of Orthodontic Wires Ravichandra Sekhar Kotha 1 , Rama Krishna Alla 2, *, Mohammed Shammas 3 , Rama Krishna Ravi 4 1 Department of Pedodontics, Dr. Sudha Nageswararao Pinnamaneni Siddhartha Dental College & Hospital, Gannavaram, Andhra Pradesh, India 2 Department of Dental Materials, Vishnu Dental College, Bhimavaram, Andhra Pradesh, India 3 Department of Prosthodontics, Sri Rajiv Gandhi College of Dental Sciences, Bengaluru, Karnataka, India 4 Professor, Department of Conservative Dentistry & Endodontics, SB Patil Dental College, Bidar, Karnataka, India *Corresponding author: Rama Krishna Alla: ramakrishna_dentalmaterials@rediffmail.com Received 18 September 2013; Accepted 1 December 2013; Available online 1 March 2014 Orthodontic wires are components of fixed appliances used to carry out the necessary tooth movements as part of orthodontic treatment. A variety of materials like metals, alloys, polymers and composites are used to produce orthodontic wires. The properties of orthodontic wires are evaluated by various laboratory tests like tensile, torsional, and bending tests. However, oral conditions may influence their behaviour and it is important for the clinician to understand the properties of orthodontic wires as well as their clinical implications to turn out optimal results. This article reviews different materials used for manufacturing orthodontic wires and their properties along with clinical implications. Review Article Introduction The aim of orthodontic treatment is to move the teeth to a targeted position by the application of forces to them. An ideal force is the one that produces rapid tooth movement without damage to the teeth or periodontal tissues. Different biological and other factors like the type of movement and tooth size are the important factors to be considered during application of the force, but it is difficult to precisely determine the value of the ideal force [1], orthodontic/orthopedic forces usually range from 01.5-5 N [2,3]. Application of lower forces produces the optimal results and application of excessive force exceeding vascular blood pressure reduces cellular activity in periodontal tissues and slows down or stops tooth movement at least for a period of time [4]. The quality and performance of treatment can be improved by the application of lower forces and achieves a wider range of movements between sessions. During orthodontic treatment, orthodontic wires are used as fixed appliances to apply forces to the teeth. They release the energy stored upon its placement by applying forces and torque to the teeth through the appliances placed on them [5]. Therefore, an orthodontist should have adequate knowledge of the biomechanical behaviour and clinical applications of orthodontic wires to design the treatment plan. Earlier gold was most commonly used as orthodontic wire. These gold wires were expensive. After gold wires, stainless steel wires were commonly used since they are inexpensive and had improved mechanical properties. Cobalt-chromium, nickel-titanium, beta- titanium and multistranded stainless steel wires have been developed with extensive range of properties due to the advancements in the recent technology. Tension, bending and torsional tests are used to measure the properties of orthodontic wires and all these tests are completely different stress states investigating different characteristics related with wire performance [6-8]. The clinician should consider a variety of wire parameters and characteristics as necessary since no wire is appropriate for all treatment stages and no wire is ideal. The ideal requirements of orthodontic wires are discussed in table 1. Types of Orthodontic Wires Stainless Steel (SS) Wires The austenitic 18-8 stainless steel type is most commonly used. It contains chromium and nickel content of approximately 18% and 8%, respectively. The most important quality of 18-8 stainless steel is its high resistance to corrosion by the formation of a passivated