To analyze the current literature in order to compare the outcome of orthodontic treatment with fixed appliances versus aligners in terms of effectiveness and efficiency. An electronic search was undertaken through PubMed, Cochrane, and ScienceDirect. Only randomized controlled trials (RCTs) were included. This literature review was carried out according to the PRISMA criteria (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The risk of bias in included studies was assessed using the Cochrane ROB-2 tool. Ten articles were retained. Some heterogeneity of the results was noted and it remains difficult to come up with clear and consensual clinical recommendations. It seems that the aligners were as effective as a fixed orthodontic treatment on class 1 malocclusions, but, some dental movements remain difficult to control like vertical movements and rotation. Conversely, the aligners are increasingly favored by patients, for esthetic and comfort reasons. This review shows that the future of aligners is very promising. Studies comparing fixed orthodontics and aligners have shown that each has its own specificities. A precise diagnosis, knowledge of biomechanics, and the limits of each means are the conditions required to achieve a result in line with the initial treatment objectives.