Local delivery of EGF–liposome mediated bone modeling in orthodontic tooth movement by increasing RANKL expression

AimsIt has long been demonstrated that epidermal growth factor (EGF) has catabolic effects on bone. Thus, we examined the role of EGF in regulating mechanically induced bone modeling in a rat model of orthodontic tooth movement.Main methodsThe maxillary first molars of rats were moved mesially using an orthodontic appliance attached to the maxillary incisor teeth. Rats were randomly divided into 4 groups: (G1) administration of PBS (phosphate buffer saline) solution (n = 24); (G2) administration of empty liposomes (n = 24); (G3) administration 20 ng of EGF solution (n = 24); and (G4) 20 ng of EGF–liposomes solution (n = 24). Each solution was injected in the mucosa of the left first molar adjacent to the appliance. At days 5, 10, 14 and 21 after drug administration, 6 animals of each group were sacrificed. Histomorphometric analysis was used to quantify osteoclasts (Tartrate-resistant acid phosphatase (TRAP) + cells) and tooth movement. Using immunohistochemistry assay we evaluated the RANKL (receptor activator of nuclear factor κB ligand) and epidermal growth factor receptor (EGFR) expression.Key findingsThe EGF–liposome administration showed an increased tooth movement and osteoclast numbers compared to controls (p < 0.05). This was correlated with intense RANKL expression. Both osteoblasts and osteoclasts expressed EGFR.SignificanceLocal delivery of EGF–liposome stimulates osteoclastogenesis and tooth movement.