Effect of Air-Polishing on 3D Surface Integrity of Composite Dental Restorations—Comparison of Three Different Powders with Reduced Abrasiveness

Composite restorations are inevitably exposed to prophylactic procedures associated with a risk of surface damage (loss of substance and roughening). The aim of the present study was to compare the effect of air-polishing with three different powders of reduced abrasiveness on composite fillings. Forty-eight specimens of microhybrid light-cure composite were randomly divided into three groups (n = 16 each), scanned in 3D and air-polished with the following: sodium bicarbonate (40 µm), glycine (25 µm) and erythritol (14 µm), respectively. Then, the specimens were rescanned and the data were processed in specialized 3D analysis software. Loss of composite material was visible in all specimens. The estimated mean composite volume loss was higher for sodium bicarbonate and erythritol (0.09 mm³ and 0.08 mm³, respectively) than for glycine (0.05 mm³). No statistically significant differences were found between sodium bicarbonate and erythritol. Powder particles were additionally characterized from SEM images (N = 1600 per powder), using equivalent circular diameter (ECD) and shape descriptors (aspect ratio and circularity). Therefore, glycine powder should be preferred when the primary goal is minimizing composite abrasion. When higher composite material removal is acceptable, erythritol and sodium bicarbonate may be considered to be interchangeable under the present conditions due to their comparable abrasive effect.