Influence of psychological stress exposure on orthodontic therapy: A comprehensive review

: The aim of the present study was to comprehensively review the influence of psychological stress exposure (PSE) on orthodontic therapy (OT). Original clinical and experimental studies were assessed. Quality assessment of experimental studies was performed using the Animal Research Reporting In Vivo Experiment (ARRIVE) guidelines. Six studies (2 clinical and 4 experimental) were included. One clinical study showed that PSE during OT significantly increases nickel release from orthodontic appliances into the saliva. In another study, maternal support was found to be an important predictor of the outcome of OT. In one experimental study, chronic PSE increased orthodontic tooth movement (OTM), and in two experimental studies, PSE decreased OTM. One study on rats reported that PSE is not a risk factor for orthodontically-induced root resorption during OTM. One experimental study showed a significantly higher number of osteoclasts in the bone on the side of OTM in restrained rats compared with unrestrained rats. One study showed decreased osteoclast counts in the bone during OTM under PSE. The lowest, highest, and mean ARRIVE scores (out of 20) for the experimental studies were 16, 18, and 16.75 ± 0.96, respectively. The role of PSE in clinical orthodontics remains unclear, most likely due to a lack of studies in humans. Further power-adjusted, well-designed, and randomized studies are needed.