Orthodontic Tooth Movement Assessment Under Shock Wave Therapy

Objectives: Investigate the effect of extra corporeal shock wave therapy (ESWT) on orthodontic tooth movement in a rat model.
Methods: Thirty two, 10-week-old rats were divided in 4 groups, with/without activation of a 10g orthodontic force (OF) to move the maxillary left first molar mesially, and treated with a single episode of 1000 shock waves at the beginning of the experiment (or sham ESWT as control). After 3 weeks, all rats were sacrificed and the maxilla was scanned using microcomputed tomography. The amount of tooth movement was measured along with microarchitectural parameters, including volumetric bone mineral density (vBMD), porous volume fraction (PoV/TV) and trabecular separation (Tb.Sp) of alveolar bone in both the compression and tension sides.
Results: No difference was found in either the magnitude of tooth movement or any of the microarchitectural parameters between the groups without OF application (SW versus negative control). However, when OF was applied, we recorded an average tooth movement of 680.1 µm and ~2-fold increase in porosity (PoV/TV) on the compression side. The presence of immature, newly formed bone on the tension side was evidenced by the lower vBMD and greater PoV/TV and Tb.Sp. Importantly, the addition of ESWT further stimulated tooth movement by 36% (p=0.014). In the compression side, the effect of OF+SW was associated with a similar effect on PoV/TV (as in OF alone) but SW also induced a significant decrease in vBMD, whereas OF alone did not (-7.72% versus -2.70%, respectively, p=0.02). In the tension side, despite the accelerated tooth movement, no difference was observed in the newly formed bone between the OF groups (OF versus OF+SW).
Conclusions: The application of shockwave therapy during orthodontic tooth movement increased the rate of tooth movement possibly by accelerating bone resorption in the compression side, while preserving bone formation rate in the tension side.