Orthodontic Elastics: A Narrative Review of Biomechanics, Biological Responses, and Evidence-Based Clinical Guidelines for Everyday Practice

Orthodontic elastics remain fundamental auxiliaries in both fixed appliance and clear aligner treatment, providing versatile intermaxillary and intra-arch force systems. Their clinical performance is determined by lumen diameter, material composition, elastic memory, and force decay behaviour, which together influence the periodontal ligament response and surrounding hard and soft tissues. Latex elastics generally provide higher initial force levels and superior elastic recovery but are associated with risks of mucosal irritation and hypersensitivity. Non-latex alternatives improve biocompatibility yet tend to show greater force degradation over time. Medium-force elastics (approximately 3.5-4.5 oz) are commonly used for sagittal correction, whereas lighter 2-3 oz configurations are preferred for vertical control, finishing, and intercuspation. The increasing integration of skeletal anchorage and aligner therapy allows more precise vector control and helps to minimise unwanted effects such as molar extrusion, occlusal plane rotation, and incisor tipping. This narrative review summarises current evidence on the biomechanics, material properties, biological responses, and clinical applications of orthodontic elastics, and synthesises practical recommendations for everyday practice. A structured, non-systematic search of PubMed, Scopus, and Google Scholar identified relevant clinical trials, laboratory investigations, systematic reviews, and key textbook chapters on force delivery, force decay, biocompatibility, compliance, and clinical outcomes. On the basis of the available evidence, light, continuous forces within the range of approximately 70-120 g, combined with at least twice-daily elastic replacement and rigorous attention to vector control, appear optimal for safe and efficient tooth movement. Material selection should balance mechanical stability with biocompatibility, particularly in patients with suspected latex sensitivity. Mastery of elastic biomechanics, awareness of biological limits, and proactive management of patient compliance together underpin predictable and patient-centred outcomes.