Polysilsesquioxane with potent resistance to intraoral stress: Functional coating material for the advanced dental materials

• Polysilsesquioxanes are introduced as a coating material for surface modification of dental retainers. • Polysilsesquioxanes have a ladder-like structure with antibacterial groups in a siloxane matrix. • The surfaces of the dental retainers are functionalized by the self-assembly of the polysilsesquioxane. • The coated surfaces have excellent antibacterial activity and mechanical resistance to intraoral stress. • The clinical application potential of this polymeric nano-coating was demonstrated in in vivo experiments. Since the oral cavity is a harsh environment where various germs and chemical and mechanical stress exist simultaneously, well-organized hybrid technology should be considered in the design of cutting-edge dental materials. Although the Clear Overlay Appliance (COA) is widely used as a transparent orthodontic device, it still requires specific modifications to overcome the poor durability and frequent contamination that cause the patient's therapeutic burden. Herein, robust polysilsesquioxane (PSQ) containing quaternary ammonium cations (QACs) and long alkyl chains (LACs) in a durable siloxane matrix are reported as coating materials for the advanced COAs. The PSQ coatings are engineered to have a ladder-like structure that exhibits excellent stability under various pH and enzymatic conditions. Experiments simulating the dynamic intraoral are established to investigate the effects of PSQ coatings for the functional improvement of COA. The QACs and LACs firmly fixed to the siloxane matrix cause bacterial contact killing to prevent the contamination of COAs in the environment exposed to bacteria. The ladder-like siloxane matrix of the coating protects the COAs from intraoral abrasion forces and shearing movements with its flexible adaptability to external stresses. This study clarifies the clinical application potential of the coated COAs via in-vivo experiments using the beagle model.