Evolution of the efficiency and predictability of clear aligner therapy: a narrative review

Background:- Clear aligners have provided patients willing to undergo orthodontic treatment with a highly aesthetic and comfortable alternative to conventional braces and hence are gaining popularity especially among adults who wish to have their smile corrected. Clear aligner technology has evolved over the last 20 years and is continually being modified to achieve most predictable tooth movements possible. However, there is not enough clinical research available to describe the complete predictability of the appliance and hence the overall efficiency of outcome is controversial. Although clear aligner therapy is an aesthetic and comfortable treatment option, it has its limitations. This review highlights on the evolution of clear aligner technology and the changes it underwent till date to provide efficient tooth movements comparable to conventional fixed appliance. It discusses in detail on the ability of clear aligners to predictably achieve tooth movements like rotations, mesio-distal tipping, bodily movement, alignment, intrusion, extrusion and anterior bucco-lingual tip (root torque) posterior bucco-lingual tip (expansion). Simple tooth movement like tipping is fairly predictably achieved by clear aligner therapy, but complex movements require adequate treatment planning and use of additional auxiliaries like attachments, intra-oral elastics, inter-proximal reduction, power ridges, auxiliary anchorage devices and over correction in some tooth movements to improve their outcome. The inclusion of such additional aids can help provide a more stable, predictable and efficient outcome for patients and the scope for improvement in treatment outcomes is immense considering the constantly evolving appliance and innovative treatment strategies on the part of clinicians.