Clear aligners are removable appliances produced from a digital impression that move the teeth gradually towards the planned position. Because they can be removed while eating and brushing, maintaining oral hygiene is easier. The progress of the treatment depends on the aligners being worn for the period specified by the dentist. Each set of aligners is used for a certain period. At the end of treatment a retention appliance is fitted so that the teeth maintain their position. The suitability of clear aligner treatment varies from case to case and is determined after an orthodontic assessment.