Effect of alumina particle morphology used for air abrasion on loss of enamel and luting composite resin

ObjectiveTo evaluate the volume loss after air abrasion with alumina particles with different morphology on bovine enamel and luting composite resin.MethodsAir abrasion was performed on 12 unscathed bovine teeth and 72 luting composite resin discs with 85 μm round-shaped and 50 μm sharp-edged alumina particles applied for 20 s, 40 s and 60 s (n = 12). Air abrasion was standardized by uniform areas of 2 mm diameter, a pressure of 0.25 MPa and a distance of 3 mm. The volume loss was determined by using a laboratory scanner.ResultsAir abrasion with round-shaped alumina particles was mostly not measurable with the laboratory scanner, while sharp-edged alumina air abrasion resulted in significant loss of enamel. The median of volume loss by sharp-edged alumina particles ranged from 0.78 mm³ (20 s) to 2.52 mm³ (60 s). In contrast to round-shaped alumina the removal caused by sharp-edged alumina increased significantly with increasing application times (p ≤ 0.05). For air abrasion on luting composite resin the median of the removed volume ranged from 2.25 mm³ (20 s) to 6.18 mm³ (60 s), while round-shaped alumina showed a range from 0.45 mm³ (20 s) to 1.40mm³ (60 s). The round-shaped alumina produced a statistically significant lower volume loss than sharp-edged alumina for all three air abrasion times.SignificanceThe 85 μm round-shaped alumina particles removed less composite resin than 50 μm sharp-edged alumina particles but barely any enamel, making it an option for removing composite resin residues from enamel.