Minimally Invasive Accelerated Orthodontic Techniques: A Clinical, Radiological, and Histological Comparison on a Rat Model

Background: Accelerated orthodontics encompasses a group of techniques designed to facilitate the faster movement of teeth. Many techniques developed are designed to cause a controlled injury to the cortex of the bone resulting in a transient osteopenia, also known as the regional acceleratory phenomena (RAP). Little research has been done to compare these techniques and describe their effects on the periodontium. Objective: To clinically, histologically, and radiographically compare several minimally invasive techniques for inducing accelerated orthodontics. Methods: Sixty 8-9-week-old male Sprague Dawley rats were used for this investigation. An orthodontic device consisting of a 50g NiTi closed coil spring was applied to allow for the mesial movement of the upper left first molar. Rats were divided into 4 groups, one control (n=15) and 3 minimally invasive accelerated orthodontic interventions consisting of Piezocision (n=15), Propel (n=15), and pulsed electromagnetic fields (PEMF) (n=15) were included. Five rats from each group were euthanized for histology at 3 time points from baseline at Day 7, Day 21 and Day 49. Histomorphometric and descriptive analysis were performed using axial crosssectional slides of the mid-root region. For clinical analysis, the distance from incisors to test molars were measured with digital calipers at baseline and post-treatment time points. Cone beam computed tomography and micro computed tomography were performed. Results: Bone density was found lower in the Piezocision and Propel groups at day 21, and the periodontium reorganizes by day 49. Piezocision had statistically significant reductions in histologic and radiographic bone density (p\u3c0.05). Conclusion: Decortication techniques, such as Piezocision and Propel, resulted in more osteopenia and tooth movement. Utilization of decortication may facilitate tooth movement through the alveolus to provide an accelerated and safe movement. VI Pulsed electromagnetic fields may demonstrate the potential for regulating bone metabolism without decreases in bone density