Referring to the debate on the extraction or non-extraction known as "the Great Controversy in Orthodontics," scientific literature aims to critically assess the available evidence regarding the performance of clear aligners in the orthodontic treatment of complex cases and their ability to achieve predictable outcomes in premolar extraction based treatments. The weakness of the aligner system mainly consists of the differences found between predicted and achieved tooth movements. The knowledge of biomechanic’s weakness in the treatment of complex cases accompanied by premolars extraction made with the clear aligners could help the clinician to preform specific treatment plans in selected patients. An accurate diagnosis plays a crucial role in defining the eligibility of patients and their virtual treatment planning, the competent clinical management of extraction spaces and the consequent and subsequent performance of clear aligners. In light of the existing reviews in the literature, the clinician could recognize the patient who benefits most from this type of biomechanical strategy in extraction cases treated with clear aligners. The clinician will be more sure that the treatment is really effective and efficient only by selecting the patient who has certain clinical characteristics and who really wants to collaborate since the success of the therapy depends on the patient's motivation especially in treatments that require more time, such as the one accompanied by tooth extraction.


Learning Objectives
After this lecture, you will be able to recognize how scientific literature has pointed out the limitations of using clear aligners to achieve controlled tooth movement in extraction treatment in terms of anchorage loss and inadequate incisor retraction.
After this lecture, you will be able to demonstrate how the predictability of orthodontic tooth movements through clear aligner among premolar extraction cases could be improved by using different methodologies such as different stiffness of aligners, appropriate protocols, attachments design, auxiliaries, by calibrating the amount and sequence of movements and last but not least, by studying the eligibility of the patient.
After this lecture, you will be able to recognize that unwanted tooth movements should be rigorously assessed in decision making if using the clear aligners system and in the virtual treatment planning through the accurate selection of the patient with some occlusal characteristics (open bite tendency, severe crowding, big size of the clinical crowns of teeth..)