Effects of types of air polishing powders on roughness, microhardness, color, and gloss of gingiva-colored resin-based composites

Background: This study aimed to evaluate the effects of air polishing powders on the roughness, microhardness, color, and gloss of two types of gingiva-colored resin-based composites (GCRBCs). Methods: Disc-shaped specimens were prepared from two GCRBCs (Gradia Plus Gum, GC: Group G; Crea.lign, Bredent: Group C). Specimens subjected to air polishing were divided into two subgroups (n = 16): erythritol (Group G-e, Group C-e) and sodium bicarbonate (Group G-s, Group C-s). The roughness (Ra), microhardness (VHN), color (Delta E*(ab) and Delta E00), and gloss (GU) values of all samples were measured before and after the applications. The data were analyzed by dependent t-test and two-way ANOVA. Results: Surface roughness showed statistically significant differences between initial and final measurements across all groups (G-s: p < 0.001; C-s: p = 0.002; G-e: p = 0.003; C-e: p = 0.011), with final Ra values being consistently higher than initial ones. Group C-e did not show significant differences (p = 0.294) in terms of microhardness after treatment, while hardness decreased in all other groups. In the final measurements, significant differences in color values were observed based on the type of powder applied (p = 0.026 for Delta E-ab; p = 0.048 for Delta E-00), with sodium bicarbonate causing more pronounced changes compared to erythritol. Significant differences were observed in initial and final gloss values for all subgroups (p = 0.00). Conclusion: It was observed that air polishing, particularly with sodium bicarbonate, can lead to significant roughness and discoloration in GCRBCs. Consequently, it is crucial to employ air-polishing devices correctly, limit their use on resin-based composite restorations, and opt for less abrasive polishing powders. These practices are essential to prevent increased surface roughness and surface microhardness and preserve color and gloss in GCRBCs.