Effects of Low-intensity Ultrasound on Root Resorptions Induced by a System of Associated Forces

Introduction The bio-stimulatory effects of low-intensity ultrasound on dental tissues which were clinically introduced in 2004 demonstrated a reduction in root resorption in maxillary premolars subjected to a force level of 50 g. Similar results by applying a torque of 50 g to the maxillary premolars were obtained in 2016; however, the effects of low-intensity pulsed ultrasound (LIPUS) on the presence of high-intensity forces are not yet known. Aim The purpose of this study was to examine the effects of LIPUS on a sample of 40 patients. Methods The analysis was conducted by applying two forces to teeth no. 14 and 24, each with an intensity greater than 50 g, and applied at two different points on the coronal surface. Subsequently, LIPUS was applied daily for 20 minutes to tooth no. 14, while tooth no. 24 served as a control. The study lasted for 28 days. Results Overall, the group treated with LIPUS demonstrated an improvement in the average total volume and percentage of root resorption compared to the control group. The same results emerged for the diameter, depth, and surface of the gaps of resorption. Conclusion This study showed that it was possible to reduce root resorption in the presence of forces with intensities greater than 50 g. Nevertheless, a longer period of study will make it possible to obtain more rational results as to the effectiveness of low-intensity ultrasound on root resorption induced by orthodontic treatment.