Abstract
Clear aligners are gaining more popularity, as most patients, especially adults, dislike the appearance of fixed appliances. In 1997, Align Technology (c) (Santa Clara, CA) released the Invisalign (R) system. The company used both computer-aided design (CAD) and computer-aided manufacturing (CAM) to produce its orthodontic appliances. This technology, which allows for multiple tooth movements from a single impression, introduced the clear aligner as it is now known. At the beginning, the Invisalign (R) system was used to treat simple tooth movement. However, as it developed, the manufacturer began using attachments and intermaxillary elastics to obtain different movements, so Invisalign (R) became a viable alternative to fixed appliances. Different aligner systems similar to Invisalign (R), such as ClearCorrect, etc., became available on the market, and they use the same principle to obtain the desired results. This review investigated the indications and contraindications of clear aligner therapy (CAT), including its efficiency and limitations; patient comfort and acceptance; and periodontal health, root resorption, and stability. In conclusion, CAT has been improved over the last 18 years and is still being improved. The treatment results depend on the clinician's own experience, case selection, and patient adherence. The clinician should be clear about the advantages and disadvantages of CAT, and the patient should be made aware that he/she should wear the appliance for 22-23h/day and only remove it while eating. The limitations of this study are lack of comparison between available CAT systems, the types and mechanics of movement produced by different types of attachments, and the cost.