Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 23 0 2026 10 10 4849 4849 Zahraa Almayyahi Department of Prosthodontics, College of Dentistry, University of Baghdad, Baghdad, Iraq Bayan Khalaf Department of Prosthodontics, College of Dentistry, University of Baghdad, Baghdad, Iraq 2023 05 30 2024 07 14 Objectives: Heat-cure acrylic resin is commonly used for the fabrication of denture base; however, it does not meet all the ideal requirements of a denture base material. This study was performed to assess the surface hardness and roughness of natural wool fiber-reinforced heat-cure acrylic resin as a denture base material. Materials and Methods: Sixty acrylic specimens were fabricated in this in vitro study; they were divided into three main groups. The first group (control) included acrylic specimens without fiber reinforcement, the second group (NW) included acrylic specimens reinforced with 0.25wt% natural wool fibers and the third group (SW) included acrylic specimens reinforced with 0.25wt% silane-treated natural wool fibers. Each group was further subdivided into two subgroups based on the tests performed, surface hardness test group and surface roughness test group. Surface hardness was measured by a Shore D hardness tester. A profilometer was used for measurement of surface roughness. The results were statistically analyzed using one-way ANOVA and Tukey's post-hoc test and P≤0.05 was considered statistically significant. Results: The SW group had the highest mean surface hardness value, followed by the NW group, whilst the control group had the lowermost mean value. However, the statistical significant difference was only evident between the SW group and the control group (P=0.018). Meanwhile, no statistically significant difference was found in surface roughness among the tested groups (P>0.05). Conclusion: The surface hardness of heat-cure acrylic resin can be improved by reinforcement with silane-treated natural wool fibers without significantly affecting its surface roughness. https://fid.tums.ac.ir/index.php/fid/article/view/4849 https://fid.tums.ac.ir/index.php/fid/article/download/4849/2247