Inhibitory effect of exogenous IL-4 on orthodontic relapse in rats.

Abstract

Interleukin-4 is proven to regulate bone metabolism. This study aimed to assess the effect of exogenous interleukin-4 on orthodontic relapse. Bilateral maxillary first molars of 25 male Sprague Dawley rats were moved mesially for 3weeks using orthodontic appliances an activating force of 50g. After tooth movement, exogenous interleukin-4 was injected into the buccal and palatine sides of the right maxillary first molars (experimental group), and phosphate-buffered saline was injected at the same sites on the left side (negative control group). At the end of the study, the relapse distance between the mesial fissure of the first molar and the distal fissure of the second molar was measured. Three different histological stains were used to visualize the changes in the periodontium. After interleukin-4 injection, the relapse distance significantly reduced. Time-dependent effects played a more important role than the dose-dependent effects, and there was no correlation between these factors. Tissue staining showed that interleukin-4 reduced osteoclastogenesis and promoted osteoblastogenesis. Exogenous interleukin-4 reduced the relapse of orthodontically treated teeth by promoting osteoblastogenesis and inhibiting osteoclastogenesis. Our findings can potentially benefit specialists in the future by improving their patients' treatment outcomes.