A major aspiration in advanced materials is to create artificial adhesive surfaces for wearable medical devices to meet the demands of the body's challenging settings and dynamics. For instance, dentures replace missing teeth and operate within the oral cavity, where an interplay between forces, muscles, saliva, and roughness of mucosa undermine their ability to grip oral tissues. Consequently, the lack of effective retentive strategies represents a source of dissatisfaction for denture wearers globally. Nature is rich in examples that employ physical and chemical adhesive strategies to optimize interfacial forces in dry and wet environments. Here, keratin-coated octopus-like suction cups are presented at the micro- and macroscale to improve the retention of rigid poly(methyl methacrylate). Microtopographies are obtained using two-photon polymerization and maskless lithography, while denture prototypes with macrotopographies are derived via digital light processing 3D printing. Results suggest that microtopographies and keratin-coated surfaces sustain higher maximum adhesion stress than the non-topographical and non-coated surfaces in moist environments, where retention is typically lacking. Proof-of-concept dentures demonstrate higher maximum detachment forces than conventional dentures with and without denture adhesive within dry and wet environments. This interdisciplinary research highlights the potential application of a nature-inspired physico-chemical approach in the next generation of complete dentures.