Three-dimensional defect evaluation of air polishing on extracted human roots

Root surfaces experience continuous abrasive instrumentation during lifelong periodontal maintenance. Periodontists need both effective and minimally abrasive debridement techniques. Air polishing devices might, therefore, constitute a good alternative to mechanical instrumentation. Because little is known of the three-dimensional shape and volume of the abrasion caused by different powders, it is the aim of the study to investigate the three-dimensional extent of these defects.

Cementum-covered roots of 20 extracted human premolars were coated with resin caps, leaving four areas with identical diameter open for instrumentation using bicarbonate powder and glycine powder. Treatment times were 5 and 10 seconds in a first interval and 10 seconds in a second interval. Maximum settings were chosen for power and lavage. The teeth were scanned using microcomputed tomography initially and after every treatment interval. Differences in volume and defect depths were calculated by superimposition of the scans and tested for significance (Wilcoxon test, P <0.001).

Defect volumes (in mm(3)) presented in medians (interquartile ranges) for the bicarbonate powder after 5, 10, 15, and 20 seconds, respectively, were 0.16 (0.11), 0.28 (0.16), 0.32 (0.18), and 0.41 (0.28), and for glycine powder, 0.00 (0.02), 0.01 (0.05), 0.03 (0.11), and 0.06 (0.1). For each time period, abrasion caused by glycine was significantly lower (five- to 20-fold) compared to defects caused by bicarbonate.

In patients with exposed root surfaces, cleaning with bicarbonate powder cannot be recommended. Less abrasive glycine powder, however, demonstrated non-critical substance loss.