Effect of Varying Intensity Levels of LIPUS (Low Intensity Pulsed Ultrasound) On The Rate of Orthodontic Tooth Movement in Mice

The effects of LIPUS on orthodontic tooth movement (OTM) has been studied before, but there is a big controversy over the role of LIPUS on the rate of OTM. Also the mechanism of this process is largely unknown. The aim of the present study was to investigate the effect of different intensities of LIPUS on OTM, as well as anabolic and catabolic properties on the bone. For this reason 24 animals were randomly divided into four groups, and on each group different intensities of LIPUS were applied (control, 15 mW/cm2, 30 mW/cm2, and 50 mW/cm2 groups). All animals received orthodontic appliance and tooth movement on the right side of the maxilla, and left side was used as control. A combination of micro-CT analysis, TRAP staining and immunohistochemistry was used to analyze and compare the rate of tooth movement, bone density, osteoclastic activity and bone markers between the four groups. Our results showed the rate of tooth movement changes depending on the intensity of ultrasound. There was a significant increase in the rate of tooth movement in 30 mW/cm2 group compared to 15 and 50 mW/cm2. Osteoclasts number was increased in 30 group compared to 50 and 15 mW/cm2, and also expression of important paracrine factors detected, such as VEGF and PGE2, varied based on the intensity. In conclusion OTM changes with using LIPUS. These changes in OTM happen through series of biological reactions controlling PGE2 and VEGF expression as well as osteoclast numbers in response to the force. LIPUS has an application in clinical orthodontics for acceleration or retention purposes.