To determine and compare the effects of high-frequency mechanical vibration (HFV) with light force and optimal force on the tooth movement and root resorption in rat model. Materials and MethodsSeventy-two sites in 36 male Wistar rats were randomly assigned using a split-mouth design to control (no force/no vibration) or experimental groups: HFV (125 Hz), light force (5 g), optimal force (10 g), light force with HFV, and optimal force with HFV for 14 and 21days. The amount of tooth movement, threedimensional root volume and root resorption area were assessed by micro-computed tomography and histomorphometric analysis. ResultsAdjunction of HFV with light force signi cantly increased the amount of tooth movement by 1.8-fold (p = 0.01), 2.0-fold (p = 0.01) at days 14 and 21 respectively. The HFV combine with optimal force signi cantly increased the amount of tooth movement by 2.1-fold (p = 0.01), 2.2-fold (p = 0.01) at days 14 and 21 respectively. The root volume in control (distobuccal root (DB): 0.60 ± 0.19 mm 3 , distopalatal root (DPa): 0.60 ± 0.07 mm 3 ) and HFV (DB: 0.60 ± 0.08 mm 3 , DPa: 0.59 ± 0.11 mm 3 ) were not different from the other experimental group (range from 0.44 ± 0.05 mm 3 to 0.60 ± 0.1 mm 3 ) with the lowest volume in optimal force group. ConclusionsAdjunction of HFV with orthodontic force signi cantly increased tooth movement without causing root resorption Clinical Relevance Using light force with HFV could help to identify alternative treatment option to reduce the risk of root resorption.

Objectives To determine and compare the effects of high-frequency mechanical vibration (HFV) with light force and optimal force on the tooth movement and root resorption in rat model. Materials and Methods Seventy-two sites in 36 male Wistar rats were randomly assigned using a split-mouth design to control (no force/no vibration) or experimental groups: HFV (125 Hz), light force (5 g), optimal force (10 g), light force with HFV, and optimal force with HFV for 14 and 21days. The amount of tooth movement, three-dimensional root volume and root resorption area were assessed by micro-computed tomography and histomorphometric analysis. Results Adjunction of HFV with light force significantly increased the amount of tooth movement by 1.8-fold (p = 0.01), 2.0-fold (p = 0.01) at days 14 and 21 respectively. The HFV combine with optimal force significantly increased the amount of tooth movement by 2.1-fold (p = 0.01), 2.2-fold (p = 0.01) at days 14 and 21 respectively. The root volume in control (distobuccal root (DB): 0.60 ± 0.19 mm3, distopalatal root (DPa): 0.60 ± 0.07 mm3) and HFV (DB: 0.60 ± 0.08 mm3, DPa: 0.59 ± 0.11 mm3) were not different from the other experimental group (range from 0.44 ± 0.05 mm3 to 0.60 ± 0.1 mm3) with the lowest volume in optimal force group. Conclusions Adjunction of HFV with orthodontic force significantly increased tooth movement without causing root resorption Clinical Relevance Using light force with HFV could help to identify alternative treatment option to reduce the risk of root resorption.