Fixed or removable? An evidence-based narrative review of orthodontic retainer selection and clinical considerations

The aim of this narrative review is to provide an evidence-based overview of fixed and removable orthodontic retainers, with particular emphasis on their effects on stability, oral health, patient satisfaction, and cost considerations to support clinical decision-making. Current evidence indicates that, in the maxillary arch, fixed and removable retainers are similarly effective in maintaining post-treatment alignment. In contrast, the mandibular anterior segment demonstrates a greater susceptibility to relapse, with fixed retainers providing superior long-term stability due to their independence from patient adherence. Fixed retainers are associated with increased plaque accumulation and gingival inflammation compared with removable appliances. However, consistent evidence of clinically significant periodontal destruction is lacking. Removable retainers are generally more favourable for oral hygiene but rely heavily on patient compliance, which tends to decline over time and may compromise treatment outcomes. Patient satisfaction is often higher with fixed retainers due to their convenience, minimal impact on speech, and reduced reliance on adherence. Evidence regarding cost-effectiveness remains limited, although available data suggest that economic outcomes are influenced by relapse risk and maintenance requirements. Overall, no single retention modality is universally superior. Fixed retainers appear advantageous in the mandible, whereas both fixed and removable approaches may be appropriate in the maxilla. Retainer selection should be individualized based on patient-specific factors, oral hygiene, and expected compliance.