Air abrasion employs which abrasive particles?

• A. Aluminum oxide (alumina)
• B. Silica sand
• C. Calcium carbonate
• D. Diamond powder

Answer: (A)

Air abrasion relies on a stream of accelerated abrasive particles to physically remove decayed or stained tooth surfaces. The abrasive needs to be hard enough to cut enamel and dentin but safe and manageable in a dental setting. Aluminum oxide fits well because its high hardness allows efficient ablation of tooth tissue, while it is relatively inert and comes in particle sizes that give controlled, predictable removal. Silica sand was used in the past but raises safety concerns from inhalation and can be less controllable; calcium carbonate is softer and less effective for removing tougher deposits; diamond powder, though extremely hard, is costly and not practical for routine air abrasion. For these reasons, aluminum oxide is the standard abrasive employed.