Orthodontics has witnessed significant advancements in recent decades. One such innovation is the advent of three dimensional (3D) printed aligners, which offer a promising alternative to traditional wire-and-bracket appliances and conventional ready-made or in-house aligners. The aim of this literature review was to critically appraise the available data and information in the literature about the direct printed aligner, its raw material and to compare it with the traditional thermoformed aligners. The research question of the study was what the proprieties are, the mechanical behaviors, the hazards of the resin used, and the aligners fabricated from the direct 3D-printed process compared to the traditional in-office or aligners made by companies. The answers were elaborated according to the PICO method: Problem: the different properties and related challenges of the use of the new materials in orthodontics, Intervention: the new resins used in and aligners produced by direct 3D-printing, Comparison: aligners produced by companies and made in-office with thermoforming, Outcome; Are the new materials used and the process of fabrication advantageous compared to the thermoformed aligners? The analysis of the studied literature showed that 3D direct printed aligners have some promising advantages in comparison with thermoformed aligners. However, studies of high-quality levels are still required to explore more in depth the potential and the limitations of this new way of manufacturing clear aligners.