Color stability and surface roughness of the alkasite restorative material: an in vitro study

Alkasites are ion-releasing resin-based restorative materials developed to combine the mechanical properties of resin composites with the potential benefits of remineralizing ion release. However, evidence regarding their surface properties and color stability remains limited. A total of 112 disc-shaped specimens were prepared. Alkasite specimens were polymerized by self-curing or high- or low-intensity light and polished using either a disc-based or spiral-wheel system. A nanohybrid composite served as the control. Specimens underwent thermocycling or 24-day coffee immersion, both combined with simulated toothbrushing. Surface roughness was assessed by atomic force microscopy (AFM) and color change by CIEDE2000. Data were analyzed using three-way and Welch’s analyses of variance. Significant polymerization × polishing interactions were observed for all surface roughness parameters ( p < 0.001) and color change ( p = 0.002). No aging-related roughness changes occurred in disc-polished alkasite groups ( p > 0.05). Self-curing combined with spiral-wheel polishing produced the greatest roughness and color changes ( p < 0.001). High-intensity light polymerization with disc-based polishing was the only test group showing color change comparable to the control after staining ( p = 0.351). Polymerization mode and polishing influenced alkasite surface and color stability. Disc-based polishing provided greater surface stability, while its combination with high-intensity light polymerization provided the most favorable color stability. Disc-based polishing may be preferable to spiral-wheel polishing systems with diamond particles to achieve better surface quality. High-intensity light polymerization may contribute to improved color stability.