Abstract
Orthodontically induced inflammatory root resorption (OIIRR) is a common complication associated with orthodontic tooth movement. The aim of this study was to investigate how dental pulp contributes to root resorption during orthodontic tooth movement. Fifteen male 8-week-old BALB/c mice were subjected to an excessive orthodontic force of 25g to induce a mesially tipping movement of the upper first molars for nine days. The expression levels of the TRAP, interleukin(IL)-17, IL-17 receptor(IL-17R), IL-6 and keratinocyte chemoattractant (KC; IL-8-related protein in rodents) proteins were determined in dental pulp (DP) by an immunohistochemical analysis. Furthermore, the effects of IL-17 on the production of IL-6 and IL-8 were investigated using human dental pulp (hDP) cells in vitro. Resorption lacunae with multinucleated cells were observed in the 25g group during the in vivo experimental tooth movement study. Immunoreactivity for IL-17, IL-17R, IL-6 and KC was detected in all of the DP tissues subjected to the orthodontic force on day nine. Moreover, IL-17 increased the release of IL-6 and IL-8 from hDP cells. The results of this study suggest that the IL-17 may aggravate the process of root resorption by increasing the production of IL-6 and IL-8 from hDP cells.
