Molar distalization is a process in the field of Orthodontics which is used to move molar teeth, especially permanent first molars, distally (backwards) in an arch. This procedure is often used in treatment of patients who have Class 2 malocclusion. The cause is often the result of loss of E space in an arch due to early loss of primary molar teeth and mesial (forward) migration of the molar teeth. Sometimes molars are distalized to make space for other impacted teeth, such as premolars or canines, in the mouth. Distalization in the maxillary arch is easier than the mandibular arch because maxillary bone has more trabecular bone than the mandible, which has higher percentage of cortical bone. One of the most popular devices that is used to distalize molars is known as Pendulum appliance and Pendex Appliance. These were developed by Hilgers in 1990.