Advances in microneedle therapeutics for recurrent aphthous ulcers

Recurrent aphthous ulcer (RAU) is a common idiopathic oral mucosal disorder marked by painful, round ulcers on non-keratinized tissues such as the buccal, labial, and lingual mucosa. These recurrent lesions impair oral function and quality of life. However, systemic treatments, such as oral or injectable medications, often exhibit limited efficacy and are associated with notable adverse effects. The effectiveness of topical treatments is often limited by the barrier properties of the oral epithelium and the dynamic oral environment. Continuous salivary flow and mechanical forces from speaking and mastication dilute, remove, or prevent adequate absorption of locally applied drugs, contributing to inconsistent therapeutic outcomes. Biomedical microneedles offer a promising alternative for delivering drugs to the oral mucosa, overcoming many shortcomings of conventional topical, oral, and injectable methods. Their capacity to painlessly breach superficial barriers enhances drug bioavailability while minimizing discomfort, bleeding, and infection risk. These features collectively improve patient adherence and provide a more acceptable treatment modality for recurrent conditions such as RAU. With rapid advancements in microneedle materials, fabrication techniques, and drug-loading strategies, emerging microneedle-based delivery systems are increasingly adaptable to the unique environment of the oral cavity. These include superior mucosal adhesion to prevent detachment, sustained drug release for prolonged retention, penetration into the pseudomembrane to bypass physical barriers, and the potential for designing multifunctional and smart-responsive systems. Such characteristics render microneedle-based systems a more acceptable and effective approach for managing recurrent conditions like RAU. This review provides an updated framework for understanding the potential of innovative microneedle technologies in the management of RAUs and highlights future opportunities for clinical translation.