An In Vitro Evaluation of the Effects of Air-Polishing Powders on Sound and Demineralised Enamel

Aim: To evaluate the effects of two air-polishing powders, during orthodontic treatment, on the surface roughness of sound and demineralised enamel. Materials and methods: Forty-two caries-free human molars were collected, and the enamel surfaces were flattened and polished. Teeth were assigned to two groups (n = 21 each), a sound- and a demineralised-enamel group (subjected to pH-cycling over 2 weeks to create artificially induced white spot-like lesions). Within each group, teeth were further assigned to three groups (n = 7 each), air polished with either sodium bicarbonate, erythritol, or a negative control (water). Each sample was treated for 5 and 150 s. The average surface roughness (Ra) for each sample was measured using white-light-sensor profilometry. Results: On sound enamel, the Ra was roughly 0.17 & PLUSMN; 0.07 & mu;m. After 150 s of air polishing, the Ra increased with erythritol (by 0.28 & mu;m), and even more so with bicarbonate treatment (by 0.68 & mu;m) (p < 0.01). On demineralised enamel, the Ra was roughly 0.79 & PLUSMN; 0.56 & mu;m. The Ra increased after 5 s of air-polishing treatment similarly with erythritol and bicarbonate powders (by 1.03 & mu;m and 1.04 & mu;m, respectively) (p = 0.025), and even more after 150 s (by 2.48 & mu;m and 2.49 & mu;m, respectively) (p < 0.001). Conclusions: On white spot lesions, one should be aware that enamel surface roughness will increase with both erythritol and bicarbonate air-polishing powders, especially with longer exposure times.