Synergistic effects of high-frequency vibration and orthodontic force on osteoclast numbers and root resorption in a rat model

Objective To evaluate how high-frequency vibration (125 Hz) combined with light or optimal orthodontic forces affects osteoclast numbers and root volume during tooth movement in Wistar rats. Materials and Methods Using a split-mouth design, 96 sites in male Wistar rats were randomly assigned to six groups: control, high-frequency vibration (HFV), light force (LF, 5g), light force with vibration (LF/HFV), optimal force (OF, 10g), and optimal force with vibration (OF/HFV). First maxillary molars were moved mesially using nickel-titanium (NiTi) closed coil springs. Root volume and osteoclast numbers were measured using Micro-CT and histomorphometry at Days 1, 7, 14, and 21. Results After 21 days, osteoclast numbers increased significantly in HFV (5.25 ± 0.48, P =. 002), LF/HFV (10.00 ± 0.41, P < .0001), OF (13.75 ± 0.48, P <.0001), and OF/HFV (15.25 ± 0.85, P < .0001) groups. Root volume decreased significantly in LF/HFV (7.75 ± 0.18 mm 3 ), OF (6.68 ± 0.24 mm 3 ), and OF/HFV (6.28 ± 0.14 mm 3 ) groups compared to control (all P < .0001). HFV alone increased osteoclast numbers but did not affect root volume. The OF/HFV group showed the highest osteoclast numbers and root volume reduction. Three-way analysis of variance revealed that time, vibration, and force significantly reduced root volume ( P < .0001). Notably, the interaction effects on osteoclast numbers were significant in LF group ( P < .0001), but not OF group ( P = .338). Conclusions Combined high-frequency vibration and orthodontic forces increased osteoclast numbers and root resorption. Light forces with high-frequency vibration promoted osteoclast formation while minimizing root resorption compared to optimal forces. Additionally, the duration of this combined treatment significantly affected the extent of root resorption.