Cold atmospheric plasma for dental CAD/CAM materials: Bleaching efficacy and a preventive approach to discoloration

Tooth bleaching is a common aesthetic dental procedure, traditionally per formed using hydrogen peroxide (H2 O2 ). With the growing use of dental prosthetic materials, their discoloration and aesthetic maintenance have become increasingly important. How ever, conventional bleaching methods may be ineffective or may compromise their surface properties. This study evaluates the bleaching efficacy of cold atmospheric plasma (CAP) on stained computer-aided design/computer-aided manufacturing (CAD/CAM) prosthetic mate rials: CEREC (a feldspathic glass ceramic) and Cerasmart (a nanohybrid ceramic in a resin matrix). Samples were stained with coffee to simulate clinical discoloration. Optimization studies identified 10 min as the optimal CAP exposure time. Three bleaching protocols were tested: 35% H2 O2 alone, CAP alone, and CAP co-activated with 35% H2 O2 . Results showed that CAP alone achieved comparable bleaching to the combined method for Cerasmart, while CEREC showed slightly better results with the combined treatment. CAP treatment also reduced restaining compared with H₂O₂ alone. CAP pretreatment had a preventive effect against discoloration, particularly Cerasmart. Surface analyses revealed minimal roughness changes in Cerasmart, whereas CEREC showed increased roughness. Bacterial adhesion was not adversely affected by CAP. Overall, CAP presents a promising alternative to conventional bleaching methods, offering effective whitening with minimal impact on surface properties and microbial behavior.