Effects of two wattages of low-level laser therapy on orthodontic tooth movement

- Variable research findings of laser therapy effects on tooth movement are found.
- Two different wattages of laser on tooth movement in rodent model were tested.
- Two laser wattages had differential effects on tooth movement.
- Laser therapy can induce molecular changes in the PDL during tooth movement.
- Laser can cause dysplastic changes in exposed gingiva.

IntroductionMixed outcomes have been found in animal and clinical studies with regard to the use of low-level laser therapy (LLLT) as a modality to accelerate orthodontic tooth movement (OTM). One major reason for the variable findings is the different methodologies and protocols for laser therapy use.ObjectiveThe aim of this study was to determine whether orthodontically moved molars exposed to two different wattages at the same energy density of LLLT exhibited differences in the amount of tooth movement and molecular and histological changes in the adjacent periodontal areas.MethodsAn orthodontic force was applied to rat upper first molars exposed to 500 mW (EX-500) and 1000 mW (EX-1000) of laser application, with a control group (CT) with no laser application. Gene expression in the periodontal ligament (PDL) and histology of the palatal gingiva of the molars were analyzed.ResultsThere was a statistically significant difference for OTM between EX-500 but not between EX-1000 and CT groups. RANKL and MMP-13 expression levels in the PDL of orthodontically moved molars, however, were increased significantly in laser-exposed groups compared to CT. Early signs of dysplasia were observed in over half of the animals in the EX-1000 group.ConclusionsOur results provide evidence for molecular changes and the potential dysplastic effects of laser on the surrounding soft tissues. Further studies are needed to better identify an optimum laser protocol to maximize the desired effect.