Loss of Enamel Caused by Two Air-Abrasion Powders
Objectives: The air-abrasion powder Orthoprophy SA-85 Soft Alumina (Danville Materials, CA, USA) is recommended for removing resin without damaging the enamel. The aim of this laboratory study was to evaluate the abrasiveness of the air-abrasion powder Orthoprophy compared to conventional 50 µm alumina particles on the surface of enamel.
Methods: Twelve extracted anterior bovine teeth with intact enamel surfaces were scanned using a laboratory scanner (3Shape A/S D900, Denmark) before treatment. Uniform air-abrasion areas were ensured by masking the surface of the teeth with tin foil with 6 punched holes with a diameter of 2 mm. Orthoprophy and alumina particle air-abrasion was applied for 20 s, 40 s and 60 s, respectively (n=12). Air-abrasion was standardized by a pressure of 0.25 MPa and a distance of 3 mm to the surface. After air-abrasion the bovine teeth were scanned again. Both scans, before and after air-abrasion, were matched by the software GeomagicWrap® (3D Systems, Germany) and the removed enamel volume was determined.
Results: Air-abrasion with Orthoprophy was not measurable with the laboratory scanner at all air-abrasion times (less than 20 µm vertical removal). In contrast, alumina particle air-abrasion resulted in significant damage of the bovine enamel. The median of the removed volume by alumina ranged from 0.78 mm3(20s) to 2.52 mm3(60s). In contrast to Orthoprophy, the removal caused by alumina increased significantly with increasing air-abrasion time (p≤0.05).
Conclusions: Air-abrasion with Orthoprophy seems to be conservative for tooth substance unlike air-abrasion with alumina particles. Therefore, it might be an interesting material when aiming to remove remnants of luting resin from enamel without damaging it.