SEM-Based Surface Imaging, Microhardness, and Cytocompatibility of Orthodontic Bite Ramp Materials: Clinical Implications for Wear Behavior and Occlusal Performance

Surface hardness is a fundamental parameter influencing wear resistance, durability, and the interaction of occlusal ramps with opposing enamel during orthodontic treatment. Five commercially available materials (Harmonize, Leone F3172-01, Transbond™ XT, Band and Build LC, and Ultra Band-Lok) and one experimental material (Composite RK-F10) were evaluated for bite ramps. Twelve standardized specimens (n = 2 per material) were prepared using EVA molds and polymerized according to manufacturers’ instructions or internal protocols. Vickers microhardness (HV) was measured following ASTM E384-16 using a 500 g load, 20 s dwell time, and ten indentations per specimen. Load dependence was assessed (25–2000 g). Surface morphology was analyzed by SEM, and cytotoxicity of eluates was evaluated on dental pulp stem cells (DPSCs) and monocyte/macrophage cell lines using CCK-8 assays (ISO 7405, ISO 10993). Significant differences in hardness were observed among materials (p < 0.05). Harmonize (64.5 ± 1.6 HV), Band and Build LC (64.4 ± 1.9 HV), and Ultra Band-Lok (64.1 ± 2.0 HV) showed the highest values, whereas Transbond™ XT exhibited the lowest value (53.7 ± 6.0 HV). Composite RK-F10 demonstrated intermediate hardness and good cytocompatibility. SEM analysis revealed differences in surface homogeneity and filler distribution. Overall, the materials exhibited distinct mechanical and biological profiles. The combined Vickers microhardness, short-term (24 h) cytotoxicity, and SEM data provide an integrated preliminary in vitro characterization of materials for bite ramps. The observed differences contribute to a comparative description of their physico-biological behavior.