Low-intensity pulsed ultrasound enhances the rate of lateral tooth movement and compensatory bone formation in rats

Introduction: Because mechanical stimulation of the periodontal ligament (PDL) by low-intensity pulsed ultrasound (LIPUS) has been shown to increase the speed of bone remodeling, the aim of this study was to examine the effects of LIPUS stimulation on the rate of tooth movement and bone remodeling during lateral tooth movement. Methods: Twelve-week-old Wistar rats were divided into two groups. The LIPUS group received experimental tooth movement with LIPUS stimulation, and the tooth movement (TM) group had experimental tooth movement without LIPUS. For the LIPUS and TM groups, the upper right first molars were moved labially with fixed appliances. LIPUS exposure was placed in the region corresponding to the right maxillary first molar. Three days after tooth movement, tartrate-resistant acid phosphatase (TRAP) was examined. Fourteen days after tooth movement, the intermolar width, bone mineral content (BMC), and bone volume fraction (BV/TV) were examined by micro computed tomography (micro-CT), and newly formed bone was measured histomorphometrically. Results: The number of TRAP-positive cells at the compressed region was obviously greater in the LIPUS group. The intermolar width was significantly greater in the LIPUS group than in the TM group. The alveolar bone around the maxillary first molar showed no differences in BMC or BV/TV between the LIPUS and TM groups. The LIPUS group exhibited a significantly greater amount of newly formed alveolar bone than the TM group. Conclusions: The present study provides evidence of the beneficial effects of LIPUS on the lateral tooth movement.

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