Evolution of orthodontics: from fixed appliances to clear aligners. An Enhanced Narrative Review

Abstract

Background: Orthodontics has moved from being mechanically and metal-based to being biologically guided and digitally designed. The development of clear aligner therapy (CAT) is a milestone that combines biomechanics, materials science, and artificial intelligence in orthodontics. Objective: This improved narrative review combines the history, material, and biomechanical development of orthodontic appliances, focusing on the shift from fixed appliances to clear aligners. Quantitative information from randomized clinical trials and biomechanical research is used to assess effectiveness, benefits, and limitations. Methods: A narrative search was conducted in PubMed, Scopus, and Web of Science from 1970 to 2025. Data from systematic reviews, finite element analyses, and clinical trials were included. The data was analyzed using quantitative summaries and graphs to show the predictability of treatment, pain scores, and biomechanical performance. Results: The accuracy of tooth movements for clear aligners is 55–70%, with tipping and intrusion being the most predictable. The aligners result in lower pain levels (mean VAS difference of −1.3), improved periodontal conditions, and treatment times equal to those of fixed appliances. Conclusion: Clear aligner therapy is a paradigm shift in orthodontics, transforming the field from reactive to predictive. Advances in artificial intelligence, smart polymers, and biomechanical modeling will further improve the precision of orthodontics.