Histological and Biochemical Investigation of the Effects of Low Intensity Pulsed Ultrasound on Orthodontic Tooth Movement

Abstract

Objective: The goal of our study is to assess the effects of low intensity pulsed ultrasound on orthodontic tooth movement in rats. Methods: For this study, 40 adult male Wistar albino rats (12-weeks old age) were used from the Animal Laboratory at Adnan Menderes University. Rats were divided into four groups each of ten. Group 1 was the untreated as a control. In group 2, an orthodontic spring was used to move teeth. For groups 3 and 4, orthodontic treatment was combined with low intensity pulsed ultrasound at 16 J/cm2 or 48 J/cm2 for 14 days, respectively. Tooth movement was measured at the last day of treatment. Serum bone alkaline phosphatase (BALP) and C-telopeptide type I collagen (CTX-I) levels were analyzed biochemically. The number of osteoclasts, osteoblasts and inflammatory cells, capillary density and new bone formation was determined histologically. Receptor activator of nuclear factor-kappa B ligand (RANKL), osteoprotegerin (OPG), vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-beta) were assessed using immunohistochemical staining. Results: BALP and CTX-I levels in group 4 were significantly higher compared to control (p<0.05). Tooth movement and the number of osteoclasts, inflammatory cells and capillary density in group 4 were significantly greater than group 2 (p<0.05). The intensity levels of RANKL and OPG in group 4 were significantly greater than group 2 (p<0.05). Conclusions: Ultrasound is a noninvasive application and promising therapy for accelerating bone remodelling during orthodontic tooth movement.