The development of antimicrobial dental materials with rapid bactericidal activity is essential for preventing early-stage bacterial colonization and biofilm formation in the oral environment. Copper (Cu) is widely recognized for its strong antibacterial properties; however, its effectiveness in rapidly inactivating different types of oral bacteria upon initial contact remains insufficiently understood. In addition, the fabrication of pure Cu structures using conventional additive manufacturing techniques is challenging due to its intrinsic material properties. Laser cladding provides a promising approach to overcome these limitations, enabling the fabrication of functional Cu-coated surfaces for customized dental applications.

In this study, Cu-coated SUS304 surfaces were fabricated via a laser cladding process, and their fast-acting antimicrobial performance was evaluated. Antibacterial activity was assessed using a modified film adhesion method. Escherichia coli and Staphylococcus aureus were selected as representative Gram-negative and Gram-positive bacteria, respectively, to simulate different bacterial responses relevant to oral environments. Short exposure times (3–15 min) were investigated to capture early-stage antimicrobial behavior. Bacterial viability was quantified by colony counting, and fluorescence staining was used to visualize bacterial membrane integrity.

The Cu-coated surfaces exhibited rapid and broad-spectrum antimicrobial activity against both bacterial species. Within 3 min of contact, a noticeable reduction in bacterial viability was observed (75% reduction), followed by a substantial decrease after 5 min (90% reduction), indicating a fast bactericidal response. Nearly complete bacterial inactivation (>99%) was achieved after 15 min. Consistent antimicrobial performance was observed for both Gram-negative and Gram-positive bacteria, suggesting that the Cu surface effectively overcomes differences in bacterial cell wall structures. Fluorescence observations revealed a time-dependent increase in membrane damage, supporting a contact-based antibacterial mechanism.

These findings demonstrate that laser-cladded Cu surfaces function as rapid-response and broad-spectrum antimicrobial interfaces. This study highlights the potential of Cu-coated surfaces for the development of infection-resistant and customizable dental biomaterials.