Analysis of air-Abrasion Efficacy Using Alumina/Hydroxyapatite for Tooth Surface Preparation.

Objectives: This study aimed to investigate hydroxyapatite (HA) and alumina + HA combination as safer alternatives for enamel cavity preparation to alumina particles, focusing on human enamel cavity cutting performance.
Methods: Thirty extracted human third molars with sound enamel were divided into three groups based on the abrasive particle used: 1) alumina (29 μm, control), 2) HA, and 3) alumina + HA. Human enamel cavity cutting times were set at 15 s, and a periodontal probe was used to measure the depth of the resulting cavities. Scanning electron microscopy (SEM) analyzed the powder morphology and shape of the cavities. Statistical analysis (Kruskal-Wallis test followed by Dunn's multiple comparisons test) was performed to compare the cavity-cutting performance of the three powder groups. The level of significance was set at 5%.
Results: On SEM analysis alumina particles appeared coarse and angular, HA particles were rounded, while the alumina + HA combination exhibited a mixed morphology. Human enamel cavity depth measurements revealed that alumina achieved the greatest cutting efficiency (mean: 2.5 mm), followed by the alumina + HA group (mean: 2.12 mm), and HA alone (mean: 0.97 mm). Statistical analysis showed significant differences between alumina and HA (p = 0.0007) and alumina + HA and HA (p = 0.02), but not between alumina and alumina + HA (p = 0.91). SEM evaluation revealed cylindrical cavities in the alumina and alumina + HA groups, while the HA group produced conical shapes.
Conclusions: The alumina + HA combination emerged as a promising alternative, offering effective enamel cutting performance. The presence of HA in this powder combination could ensure potential for enamel remineralization, which should be investigated in future studies. Our findings suggest a safer, efficient partial substitute for alumina, meriting further validation through in-vivo studies.