Understanding Orthodontic Elastics: A Biomechanical Perspective

Background Orthodontic elastics are widely used as an adjunct to fixed and contemporary orthodontic treatment for the correction of anteroposterior and vertical discrepancies. Their clinical effectiveness depends on appropriate selection of elastic type, size, force magnitude, direction, and point of attachment, together with adequate patient compliance. Objective To provide a comprehensive overview of the biomechanical principles governing orthodontic elastics, including their classification, force characteristics, clinical applications, selection criteria, biomechanics in different malocclusions, force decay, and contemporary applications with aligners and skeletal anchorage. Methods A narrative literature review was conducted using PubMed, MDPI, ScienceDirect, JMIR Publications, and ResearchGate. Articles published from 1994 to July 2025 were identified using combinations of keywords related to orthodontic elastics, biomechanics, force systems, treatment protocols, skeletal anchorage, and aligner therapy. Of 110 records identified, 95 were screened by title and abstract, 69 underwent full-text assessment, and 57 articles were included in the narrative synthesis. English-language articles addressing the biomechanics and clinical relevance of orthodontic elastics were included, whereas articles unrelated to dental elastics, clinically irrelevant studies, methodologically unsupported opinion pieces, and non-English publications were excluded. Results The biomechanical effects of orthodontic elastics varied according to elastic size, extension, force magnitude, angulation, and point of application. Class II and Class III elastics produced both horizontal and vertical force components, which changed with increasing mouth opening. The review also demonstrated the application of elastics in crossbite correction, dental midline correction, clear aligner therapy, skeletal anchorage-assisted mechanics, and extraoral force systems. Conclusion The biomechanical behavior of orthodontic elastics is complex and strategic modification of the elastic type, force magnitude, and attachment point can optimize desired tooth movement while minimizing unwanted effects for different clinical situations for achieving predictable treatment outcome.