Oral and Extra-Oral Manifestations of Hypersensitivity Reactions in Orthodontics: A Comprehensive Review

Although rare, oral manifestations of hypersensitivity reactions in orthodontic patients pose a significant clinical challenge due to their heterogeneous presentations, and can cause discomfort and pain, possibly impacting patients’ quality of life and orthodontic treatment duration and outcomes. This comprehensive review aimed to elucidate the oral, perioral, and systemic manifestations of hypersensitivity reactions in orthodontic subjects, focusing on patients with fixed appliances, removable appliances, and clear aligners, and detailing their epidemiology, macroscopic and microscopic features, allergy testing, clinical implications, and specific management strategies. Oral and extra-oral manifestations of (immediate and delayed) hypersensitivity reactions occur rarely and are due to the release of metal and non-metal ions from orthodontic appliances. They typically present as erythema, erosive–ulcerative lesions, and gingival hyperplasia, with histopathological findings showing inflammatory infiltrates. Nickel is a significant allergen, and diagnostic tests like patch tests are essential for managing these reactions. Likely due to prolonged contact with oral tissues, fixed orthodontic appliances pose a higher risk compared to removable appliances and clear aligners. Early identification and removal of allergenic materials, combined with effective treatments, can resolve symptoms and prevent recurrence. Keeping dental and medical records updated and knowing family and personal medical histories helps clinicians choose appropriate materials and counsel patients about potential risks. Proper patient education, regular monitoring, and using hypoallergenic materials are key strategies for managing these reactions.