Achievement of stable results is one of the most important goal of orthodontic treatment beyond facial and dental aesthetics, function, health and longevity of the dentition. Over the years retention as a separate phase of orthodontic treatment was largely neglected and therefore clinicians had to face the wrath of relapse of their corrections. A steady evolution in the importance of the retention and appliances has been observed over the last 50 years. Retention appliances have transformed from the bulky, acrylic removable appliances towards the more aesthetic and comfortable invisible...