Dentin Loss and Surface Alteration Through Chemical and Chemomechanical Challenge after Initial Root Instrumentation

Purpose: To assess the root surface roughness and substance loss induced by chemical and chemomechanical challenges on root surfaces pretreated with ultrasonic instrumentation, a hand scaler, or erythritol airflow.
Materials and Methods: One hundred twenty (120) bovine dentin specimens were used in this study. Specimens were divided into eight groups and treated as follows: groups 1 and 2: polished with 2000- and 4000-grit carborundum papers but not instrumented (‘untreated’); groups 3 and 4: hand scaler; groups 5 and 6: ultrasonic instrumentation; groups 7 and 8: erythritol airflow. Samples from groups 1, 3, 5, and 7 then underwent a chemical challenge (5 x 2 min HCl [pH 2.7]), whereas samples from groups 2, 4, 6, and 8 were subjected to a chemomechanical challenge (5 x 2 min HCl [pH 2.7] + 2 min brushing). Surface roughness and substance loss were measured profilometrically.
Results: The least substance loss through chemomechanical challenge was noted after erythritol airflow treatment (4.65 ± 0.93 µm), followed by ultrasonic instrumentation (7.30 ± 1.42 µm) and the hand scaler (8.30 ± 1.38 µm); the last two (hand scaler and ultrasonic tip) did not differ statistically significantly. The highest roughness after chemomechanical challenge was observed on ultrasonically treated specimens (1.25 ± 0.85 µm), followed by hand-scaled specimens (0.24 ± 0.16 µm) and those subject to erythritol airflow (0.18 ± 0.09 µm); there was no statistically signficant difference between the latter two, but they both differed statistically significantly from the ultrasonically treated specimens. No statistically significant difference in substance loss through the chemical challenge was observed between specimens pretreated by the hand scaler (0.75 ± 0.15 µm), ultrasonic tip (0.65 ± 0.15 µm), and erythritol airflow (0.75 ± 0.15 µm). The chemical challenge smoothed the surfaces treated with the hand scaler, ultrasonic tip, and erythritol airflow.
Conclusion: Dentin pretreatment with erythritol powder airflow resulted in a higher resistance to chemomechanical challenge than did dentin treated ultrasonically or with the hand scaler.