AbstractPurpose:To evaluate how different polishing techniques and coffee thermalcycling affect the surface roughness and stainability of additively and subtractivelymanufactured resins used for definitive prostheses.Materials and Methods:Two additively manufactured composite resins (Crowntec,CT and VarseoSmile Crown Plus, VS) and a subtractively manufactured resin nanoce-ramic (Cerasmart, CS) were used to fabricate 90 rectangular-shaped specimens (14×12×1 mm) (n=30). After baseline surface roughness (Ra) measurements, speci-mens were divided into three groups based on the polishing technique; conventionalpolishing with a 2-stage polishing kit (CP) and surface sealant application (Optiglaze,OG or Vita Akzent LC, VA) (n=10). After polishing, specimens were subjected to10,000 cycles of coffee thermal cycling.Raand color coordinate measurements wereperformed after polishing and after coffee thermal cycling. Color difference (ΔE00)was calculated. Scanning electron microscope images were taken at each time interval.Kruskal–Wallis or 1-way analysis of variance (ANOVA) were used to evaluateRaofmaterials within each polishing-time interval pair and different polishing techniqueswithin each material-time interval pair, while Friedman or repeated measures ANOVAwere used to evaluateRaat different time intervals within each material-polishing pair.ΔE00was assessed with 2-way ANOVA (α=0.05).Results:Other than VA-after polishing (p=0.055), tested materials had significantlydifferentRawithin each polishing-time interval pair (p≤0.038). WhenRadifferencesamong different polishing techniques within each material-time interval pair were con-sidered, CS had differences after coffee thermal cycling, CT had differences beforepolishing and after coffee thermal cycling, and VS had differences within each timeinterval (p≤0.038). WhenRadifferences among different time intervals within eachmaterial-polishing pair were considered, significant differences were observed amongall pairs (p≤0.016), except for CS-VA (p=0.695) and VS-VA (p=0.300).ΔE00values were affected by material and polishing technique interaction (p=0.007).Conclusions:Raof CS was similar to or lower than theRaof other materials, regard-less of the time interval or polishing technique. CP mostly led to lowerRathan otherpolishing techniques, whereas VA resulted in a highRaregardless of the material-timeinterval pair. Polishing reduced theRa, while coffee thermal cycling was found to have a small effect. Among tested material-polishing pairs, only CS-VA had moderatelyunacceptable color change when previously reported threshold values were considered.