With the increasing demand for beauty and health, clear aligners (CAs) have been widely applied among patients with malocclusion. However, patients treated with CAs also face some potential complications, such as demineralization, dental caries, periodontal diseases, and so on. In addition, some patients have additional needs to improve their quality of life, such as bleaching teeth. In order to prevent or solve these problems, the modification of CAs is a promising method because their extensive long-term contact with tooth surfaces makes them ideal devices for implementing adjuvant medical functions.

In this review, we discuss various advanced CAs with medical functions based on the clinical needs of patients. As far as we know, the additional functions of CAs mainly include antibacterial, remineralization, whitening, and accelerating tooth movement. These functions are achieved by two major pathways, the combination of CAs with drugs/biomaterials and increasing the capacity or affinity of drugs. In addition, we discuss the current limitations of in vitro experiments which are designed to explore the effectiveness and properties of novel CAs, and the challenges of bringing a multifunctional appliance from proposal to clinical application. At the end of this review, we provide insights into the broader prospects for the improvement of CAs.

The recurrence of head and neck squamous cell carcinoma (HNSCC) after surgical resection continues to pose a major challenge to cancer treatment. Advanced HNSCC exhibits a low response rate to immune checkpoint blockade (ICB), while photothermal therapy (PTT) can increase the infiltration of immune cells to make tumors more susceptible to cancer immunotherapy. In this regard, we designed and constructed a novel multifunctional nanocomposite comprised of oxidized bacterial cellulose (OBC), thrombin (TB), and gold nanocages (AuNCs) containing anti-programmed death 1 (PD-1) antibody (αPD-1@AuNCs), which allows the combination of therapies with remarkable postoperative antitumor immunity to control local tumor recurrence. The αPD-1@AuNCs displayed high light-to-heat conversion efficiency and induced pyroptosis under near infrared (NIR) irradiation, which activated a potent antitumor immune response. More importantly, the therapeutic system could induce tumor pyroptosis and enhance antitumor immune response by increasing T-cell infiltration and reducing the immune suppressive cells, when combined with local ICB therapy, which effectively avoided the tumor recurrence in a HNSCC postoperative mice model. Overall, the newly developed multifunctional nanocomposites could be a promising candidate for the treatment of postoperative HNSCC.