IL-1β Expression in Orthodontic Tooth Movement after Shock Wave Therapy

Background: We reported results of a preliminary study presenting the IL-1β concentration profile in crevicular fluid after induction of orthodontic force with and without extracorporeal shockwave therapy (ESWT) in a rat model for 3 days. Objectives: Further investigate the expression of IL-1β in the periodontal ligament and bone on the tension and pressure sides using a model of orthodontic tooth movement in rats that underwent ESWT. Material and Methods: An orthodontic appliance was fabricated and applied between the molars and incisors of rats. The rats were treated with a single episode of 1000 shockwaves and sacrificed on the third day. Each sample was sliced into 7 µm continuous sections in a horizontal direction and prepared for haematoxylin and eosin, tartrate-resistant acid phosphatase (TRAP) and immunohistochemistry staining for IL-1β. Results: The number/area of TRAP positive cells was statistically significantly higher in the non-treated shockwave group than in the treated group (p<0.0001). No difference was found between the negative and positive control groups and between the negative control and treated shockwave groups. Histomorphometry for IL-1β immunoreactivity revealed a statistically significant difference in the percentage of cells expressing IL-1β between the negative control group and both the treated and non-treated shockwave groups (p<0.05). The same finding was revealed for the positive control group, however no difference was detected between the control groups and the treated and non-treated shockwave groups. Conclusion: The results regarding IL-1 β expression correspond with our previously reported ELISA study on day 3 of the experiment. The application of ESWT during orthodontic force induction might reduce the inflammatory reaction in the tissue.