Performance of an alkasite restorative material under acidic conditions: surface roughness, gloss and hardness

In this study, the effects of acidic environments on the surface integrity of an alkasite-based resin composite (Cention Forte, CF) were compared with those of a nanohybrid composite (Z250 XT) and a resin-modified glass ionomer (Fuji II LC, FLC). The samples (n = 6) were immersed for 96 h at 37 °C in Coca-Cola (CC, pH 2.6), simulated gastric acid (SGA, pH 1.2) or artificial saliva (pH 6.5). Surface roughness (Ra and Rz), gloss, and microhardness were measured, and morphology was examined using scanning electron microscopy (SEM). Significant effects of material, solution and their interaction were observed (p < 0.001). In artificial saliva, CF exhibited Ra and Rz values (0.34 ± 0.03 and 2.39 ± 0.33 μm, respectively) comparable to those of FLC, intermediate gloss (46.30 ± 1.47 GU), and the lowest microhardness (59.01 ± 2.57 VHN). In CC and SGA, CF had higher roughness (Ra: 0.52 ± 0.10 and 0.71 ± 0.12 μm; Rz: 3.16 ± 0.78 and 4.05 ± 0.74 μm, respectively), lower gloss (32.72 ± 1.13 and 23.47 ± 1.18 GU), and lower microhardness (51.99 ± 3.15 and 42.70 ± 3.59 VHN) than FLC. SEM analysis confirmed these findings, showing matrix erosion and filler loss in CF. Z250 XT consistently maintained superior integrity. Clinically, these findings suggest that alkasite-based restorations may be less durable in patients with frequent dietary acid exposure or gastric reflux.