Alignment instability is one of the major pitfalls of orthodontic treatment. As a result, orthodontists tend to recommend long-term use of retainers for enhanced stability, which may require years or even decades of retainer wear. Because bonded lingual retainers are intended to serve for long periods of time in the mouth, attempts should be made to increase the success rate of these devices. Loosening of the wire in bonded lingual retainers may result from cracks within the composite that arise from deformation of the inter-dental wire. Wire choice may therefore be important for maximizing the success of lingual retainers.This book provides valuable knowledge about the bond strength of three commonly used fixed retainer wire-composite systems and the load deflection rate to bring about 0.5 mm deformation in these lingual retainer wires. This book would be instrumental for orthodontists in assessing the type of wire that will be better retained on the tooth surfaces as numerous companies are producing different types of lingual retainer wires for fixed retention.