Treatment Efficacy of Invisalign: Literature Review Update

Purpose: Inconsistency between computer prediction and actual tooth movement in Invisalign treatment always limits clinical judgment. The objective of this review was to update the evidence on the treatment efficacy of the Invisalign appliance. Material and Methods: Medical databases were screened for relevant peer-reviewed articles from 2000 to 2018 for the use of Invisalign as a treatment intervention. All human studies other than case reports and case series were included. Results: A total of 25 articles (4 RCTs, 6 prospective cohort studies, 15 retrospective cohort studies) were included. Treatment outcomes have been improving over the past 17 years. Invisalign treatment achieved results comparable with those of fixed appliances in extraction cases, except for buccolingual inclination (p<0.005) and occlusal contacts (p<0.001). For specific tooth movement, the highest accuracy was for arch expansion (upper: 72.8%, lower: 87.7%) and molar distalization (87%). Rotation of rounded tooth and overbite control with aligners was unpredictable. Conclusions: Invisalign treatment for controlling buccolingual inclination and occlusal contacts were less than ideal. None of the tooth movement was completely in line with predictions. Auxiliary or revised prescription may be needed to achieve high-quality results. Because the material, treatment design, and evaluation methods differ among studies, results should be interpreted carefully.