Comparative expression of RANK, RANKL, and OPG in keratocystic odontogenic tumors, ameloblastomas, and dentigerous cysts

Objective. The aim of this study was to compare the expression of nuclear factor kappa B (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) in odontogenic epithelial tumors and dentigerous cysts. Study design. The expression of these molecules was evaluated in solid/ multicystic ameloblastomas (n = 12) and unicystic ameloblastomas (n = 8), keratocystic odontogenic tumors (n = 19), dentigerous cysts (n = 9), and dental follicles (n = 9) by immunohistochemistry. Results. In odontogenic epithelium, a similar expression of RANK, RANKL, and OPG was observed in all samples. With regard to stroma, the number of RANK-positive and RANKL-positive cells was higher in solid/ multicystic ameloblastomas compared with dentigerous cysts. Dental follicles had lower numbers of RANK-positive, RANKL-positive, and OPG-positive cells than solid/ multicystic ameloblastomas and keratocystic odontogenic tumors. The majority of solid/ multicystic ameloblastomas (75%) and unicystic ameloblastomas (62.5%) had higher numbers of RANKL-positive than OPG-positive cells. In contrast, 62.4% of keratocystic odontogenic tumors and 100% of dentigerous cysts exhibited a higher content of OPG-positive than RANKL-positive cells. Conclusion. Our results indicate differences in the RANK, RANKL, and OPG expression in odontogenic epithelial tumors. The imbalance of these factors could contribute to the differential bone/ tooth resorption activity in these lesions.