Mechanical plaque removal methods such as tooth brushing and dental flossing have been advocated as reducing the biofilm formation. However, these mechanical plaque removal methods require good manual dexterity and can be difficult to implement in certain circumstances, such as in older patients . Exposed dentine on the root surface is more susceptible to caries than enamel. PEG can be used as an anti-biofouling material in inhibiting dental biofilm formation on the root dentine surface. Polydopamine is a bio-inspired polymer that can form a strong adhesive interaction with various substrates . It also provides a versatile platform for secondary reactions for diverse functional applications . Studies have indicated that polydopamine was effective in surface functionalization and biomolecule covalent immobilization . The covalent immobilization of biomolecules maintained stable and long-term performance. The objectives of this study were to develop a polydopamine-induced-PEG coating method for the dentine surface and to investigate its anti-biofouling effect against a multi-species cariogenic biofilm.