Healing of Orthodontically Induced Root Resorption by Ultrasound in Man

Root resorption is one of the adverse outcomes of orthodontic tooth movement. In addition to compromising the crown-root ratio, root resorption has led to increased malpractice litigation against orthodontists. A clinically acceptable treatment method of root resorption is not available in the literature up to date. Previous researches have shown that Low-intensity pulsed ultrasound (LIPUS) can enhance healing of traumatized different types of connective including dental tissues without any adverse effect. Objectives: The purpose of this study was to evaluate the effect of using LIPUS on the healing process of orthodontically induced tooth-root resorption in man. Methods: Twelve orthodontic patients who were seeking orthodontic treatment that necessitated extraction of their premolars were chosen and consented to participate in this study. For each patient, buccally activated springs were used to tip the first premolars buccally with an initial force level (50 gm) which was checked weekly to ensure continuous force level. LIPUS was applied to one side of each patient’s mouth and the other side was used as a control. The premolars of six patients were studied by scanning electron microscope (SEM) and the premolars for the other six patients were studied using regular histological technique. The number and total area or resorption lacunae, as examined by SEM, were compared between the LIPUS treated and control premolars using statistical t-test. Results: SEM study showed statistically significant decrease in number and the area of resorption lacuanae in the LIPUS treated premolars (P<0.05). Histological examination revealed healing of the resorped root surface by deposition of new cellular reparative cementum. Also, LIPUS application enhances the formation of more cementum deposition on top of the regular old cementum. Conclusions: The results of this study provide a valuable and clinically acceptable method for minimizing orthodontically induced root resorption in human.